| ? | Sunday, 11th June 2006 9:39pm - No.82 |
| What is the signal generator? |
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| RMCybernetics | Monday, 12th June 2006 1:10am - No.83 |
The signal generator used for these circuits can be any square wave signal generator with the correct amplitude.
For these circuits we used a simple 555 based squarewave generator circuit. You can see the schematics at the links below.
'Dead bug' Signal Generator
Signal Generator with PWM
The signal generator with PWM is the more stable and versitile of the two. |
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| Lydia | Saturday, 2nd September 2006 9:00pm - No.219 |
How can I tell which is the negative pole on a ignition coil, I am trying to install a tachometer in my vehicle but can't tell which is negative and which is positive.
Thank you for any help |
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| RMCybernetics | Saturday, 2nd September 2006 9:07pm - No.220 |
There are hundreds of differnt types of ignition coil, so I could not say for sure.
If it is the common cylinder type, there is usually a faint mark by he terminals. Also some have a different sized terminal for positive and negative. The positive terminal is usually the larger one.
If this does not help, try searching the model or type in google |
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| Dave | Wednesday, 6th September 2006 11:33am - No.235 |
Hi,
I've built the same ignition coil driver as the one shown above. The one with 4 power transistors and 2 ignition coils. I'm only running at 12V presently and the sparks are not that dramatic. Thin blue ones at about 2cm long. My circuit is drawing about 4.5 amps though.
Is there anything I could do to create longer sparks? Would using a 24V power supply help? I'm trying to build a Jacob's ladder.
Many Thanks |
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| RMCybernetics | Wednesday, 6th September 2006 4:10pm - No.237 |
The signal apllied to the transistors can make a big difference in perfomance. It is important to use a signal generator wit good adjustability so that you can tune it to match the coils you are using.
If the pulse width (duty cycle) of frequency is not quite right you can end up drawing lots of power but only getting a tiny output from your coils. The "Signal Generator with PWM" linked above is highly reccomended for this.
24V would help, but you should try to get better output from 12V first.
When you are drawing arcs like in a jacobs ladder the output of the ignition coils is effectivley 'shorted' and will demand a lot of current from the PSU. Keep an eye on the temperature of your transistors when doing this.
We have been working on a new driver circuit recently and it should hopefully be ready in a few days. I'll post a link here when it's ready. |
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| RMCybernetics | Thursday, 21st September 2006 4:42am - No.305 |
A new project has just been added. The DIY Pulse Controller is ideal for driving small transformers like ignition coils.
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| Bevan NZ | Thursday, 21st September 2006 6:49am - No.307 |
I assume you need a signal generator (i.e. 555 timer) for the first cct, where it says 'Input Signal'?
Thanks |
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| RMCybernetics | Thursday, 21st September 2006 4:05pm - No.308 |
Yes you need something to generte a square wave signal.
You can use a pre built one or there are schematics for 555 based ones here and here. You could also look at the coil driver circuit with the signal generator included |
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| Bevan | Friday, 22nd September 2006 3:59am - No.310 |
| ..and what sort of current does the 12V supply need/draw for either cct? Sorry meant to ask that before. |
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| RMCybernetics | Friday, 22nd September 2006 5:26am - No.311 |
The current will depend on the frequency and pulse width at which you drive a coil, but the 2n3055 transistors are rated upto 15 Amps each. The other circuit using the IRF740 is rated up to 10A
Driving a single common cylinder type ignition coil at optimum frequency/pulse width will typically draw around 5A with a load on its output.
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| Goner | Tuesday, 3rd October 2006 12:24pm - No.360 |
Hi,
just finished sticking together the 555 Pulse generator and am very happy with it. Now I finally obtained some ignition coils and want to test them right away. When building the Amp above, I got stuck with the RC-Filter. Why is it included in the first shematic, but left out in the second one, but again included in the big supply unit (the one with nine transistors)?? And what kind of ratings do the resistor and cap need? |
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| RMCybernetics | Tuesday, 3rd October 2006 3:55pm - No.363 |
These circuits are more of a guide than exact specifications for an ignition coil driver. This is because there are so many different types of ignition coils, each with different ratings. The application that you use the HV output for also effects how you may want to build the circuit.
The RC filter is recommended to reduce the chance of blowing the transistors, but the exact component values will depend on the frequency at which you drive your coils. Higher frequency would need smaller capacitor. The resistor just serves to limit the current.
It works by damping the oscilations in the coils, but it can therfore reduce the efficiency of the system.
If you are only operating your ignition coil driver with a stable load (like a neon light) on its output then you can get away with not using the RC filter. If you want to make sparks, jacobs ladders etc then you will need some sort of protection. I have destroyed a fair few 2n3055 transistors when driving ignition coils without protecive components. I recently added better (but less powerful) version here. you could add more MOSFETs in parralel though to make it tollerate bigger loads. |
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| BDSD | Tuesday, 10th October 2006 4:30pm - No.406 |
| I wish to use 4, 6 or 8 ignition coils to increase the output voltage of my system. I see that you have used four in series parallel to increase the voltage, how can one possibly use 4, 6 or 8 coils but at the same time have a single secondary output instead of the two you have in yours. |
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| RMCybernetics | Tuesday, 10th October 2006 4:39pm - No.408 |
 You can connect as many as you like in parallel, like in this image, but this only increases the output current and not the voltage.
One way might be to use one ignition coil to charge a capacitor to pulse the primary of a second ignition coil. This way could make very high voltage, but I dont think the insulation in your coil would last very long. |
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| Crispy | Thursday, 23rd November 2006 5:32pm - No.512 |
| What would be a good, safe, semi-accurate way to measure the maximum current capable of being produced by the ignition coils (with a given tuned driver circuit)? Just hooking up the leads to an ammeter would probably cause it to arc internally because the meter's internal resistance would be significant compared to the other resistive elements in the circuit (just the wires), but adding a resistor would decrease the current flow. Is there a good way to measure this current? Thanks. |
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| Crispy | Thursday, 23rd November 2006 7:11pm - No.513 |
Oops ... I think I figured out the answer to my last question ... I'll post it here for the benefit of anyone else who might want to try.
First, I'm proceeding from the assumption that the ignition coil will supply as much current as it can unless there is a load on the output with a resistance that will limit the current to less than what the ignition coil can supply.
I figured that if I connected a resistor in series with an ammeter and the ignition coil, that it would cause a voltage drop proportional to the current flowing through it (according to Ohm's law), but the current flowing through it would be constant regardless of the resistance as long as it wouldn't normally limit current to below the maximum that the ignition coil could supply. If the series resistor actually was limiting current, this could be calculated after the current was measured.
My multimeter can support a maximum of 600V across its leads, and when measuring current on the uA scale, has a measured resistance (by another multimeter) of approximately 110 Ohms. Estimating by the length of the spark gap, the 2 ignition coils that I have connected in anti-parallel are generating approximately 60kV. Since many of the factors here are estimates, I decided to proceed with my calculations from the standpoint that the multimeter could only handle 300V.
From these values, I calculated that a series resistor of approximately 22,000 Ohms would drop sufficient voltage so that the voltage drop across the multimeter would be approximately 300V. Using Ohm's law, this should allow approximately 2.7A to flow through the circuit (max), so assuming that the ignition coil can't supply that much current (which is a very reasonable assumption), it shouldn't limit the current flowing through the multimeter.
When I connected up the circuit, it didn't fry my multimeter (Yay!), and the multimeter measured approximately 8mA rms (although this varied a bit over time by maybe 300uA) from my two ignition coils connected in anti-parallel.
Measuring DC current, the multimeter measured very close to 0uA. This suggests that the ignition coil output has a duty cycle of almost exactly 50%, even though the signal generator that I am using is producing approximately a 75% duty cycle square wave.
I don't have an oscilloscope, so I don't know what the exact waveform is for the output of the ignition coil ... has anyone tested this? |
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| RMCybernetics | Thursday, 23rd November 2006 8:00pm - No.514 |
 I tested a pencil type ignition coil with 6V 50% duty cycle @ 1.85kHz.
This is a manually drawn image of the scope trace i saw from just detetcting the voltage with a small antenna about 1m away. |
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| Crispy | Friday, 24th November 2006 1:14am - No.515 |
Any idea what is causing that dip? Is it some kind of resonant effect?
Also you might want to take a look at building a large voltage divider to get more accurate measurements than what you could get just with an antenna. I'm going to make one myself if I can get the resistors, but I calculated that a voltage divider that would use .1mA of current and would provide a 100:1 ratio would need over a thousand 400V resistors. I'm trying to see if I can find some cheap resistors rated at more than 400V. |
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| RMCybernetics | Friday, 24th November 2006 9:53am - No.516 |
It looks like a highly damped ringing trace to me. When the DC is disconected from the coil, the magnetic field colapses and oscilates a little at some fundamental frequency of the coil.
I don't know if you would see the same trace if it were connected by a voltage divider, but it would be good to compaare. |
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| Andrew | Friday, 1st December 2006 3:20am - No.536 |
| Hi, I plan to build a small Jacob's ladder powered by an ignition coil driver, and I have a few questions. How many 2n3055's should I use, and how big of a heatsink will I need? Also, should I use 1 or 2 coils? Thanks! |
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| RMCybernetics | Saturday, 2nd December 2006 12:49am - No.539 |
Andrew:
You can make a small jacobs ladder using just a single ignition coil. The size that the arc will expand to is determined by the current flowing in it.
The No. of transistors needed would depend on your coil, but you could probably just use one. Each 2n3055 can handle about 15 Amps if it is kept cool enough. Typical heatsinks for TO-3 cases are quitle large.
Using 2n3055's can be tricky with jacobs ladders. the arcing can cause voltage spikes that exeed the thw 100V maximum of a 2n3055. Make sure you buy a few spare ones if you plan to draw arcs. |
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| justin | Saturday, 2nd December 2006 1:47pm - No.543 |
| i found a 555 timer 2MHz and it was 98c very cheap. would a timing compacitor be something like a microwave compacitor or dialectric one because the shop did not have any. also the led i was refering to was or is a transistor sorry im new to this. |
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| Andrew | Saturday, 2nd December 2006 11:29pm - No.545 |
| Thanks for your answer! I just have two more questions. I saw at a different site (http://users.tkk.fi/~jwagner/tesla/board.htm) that "A 10nF capacitor rated 1kV across the transistor collector and emitter... and a 60V varistor (MOV or VDR) across the ignition coil terminals... are useful to protect the transistor from voltage spikes that might kill it." Would you recommend this for my Jacob's ladder circuit? Also, if I use one coil, what should I use as the ground (the other rod of the Jacob's ladder)? A cold water pipe? The negative terminal of the power supply or battery? Thanks in advance! |
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| RMCybernetics | Sunday, 3rd December 2006 4:45pm - No.547 |
Justin:
The timing capacitor is usually quite small in size. I think a microwave one may be too large but theres no harm in trying it if you allready have one. Almost any capacitor will work, but its capacitance will determine the frequency of the circuit. A larger capacitor will produce lower frequency because it takes longer to charge.
The three legs on the transistor are explained in this link. You will only see 2 pins on an actual 2n3055 because the metal casing is used for the collector (+ve). You can use a 2n3055 datasheet to identify the other pins.
Andrew:
The suggestion on Jan Wagners page is certainly a good idea to help protect the transistors.
The ground terminal could be the battery negative terminal. |
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| Andrew | Sunday, 3rd December 2006 6:04pm - No.549 |
| Sorry for asking so many questions but I just have a few more. Would the suggestions on Jan Wagner's page be instead of or in addition to your own (D1 and RC1)? In other words should I use D1, RC1, the 10nF cap, and the MOV? Also, should I use the small transistor T1 as in your diagram or just connect the input signal to the 2n3055 as in the diagram justin posted? And would you recommend using one or two batteries? Thanks for all your help! |
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| RMCybernetics | Sunday, 3rd December 2006 7:33pm - No.550 |
I would definatley include D1, but Jan's method would possibly be better than the RC1 part. Varistors somtimes degrade over time if they are absorbing a lot of spikes, so including RC1 may help extend its lifetime.
The small transistor is only needed when driving lots of 2n3055's in parralel. If you are just using one or two then you can get away with just driving 2n3055's from the 555 output (through a 100 ohm resistor). |
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| Andrew | Monday, 4th December 2006 1:10am - No.554 |
 This is my finished circuit diagram for the project I am planning to build. I would appreciate it if you could look it over and tell me if I have made any mistakes. If you approve it I will order the parts and start building it! Thanks for all your help! |
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| RMCybernetics | Monday, 4th December 2006 9:48am - No.557 |
Justin:
Yes, a smaller capacitor would cause higher frequncy pulses in the circuit.
If you want to change the capacitance by connecting capacitors together, connecting them in series will reduce the capacitance. |
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| justin | Monday, 4th December 2006 11:12am - No.559 |
| would a variable resistor be for fine tuning in the circuit? |
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| RMCybernetics | Monday, 4th December 2006 1:32pm - No.560 |
Andrew:
Your circuit seems fine to me, but I've used that 555 circuit before and wasn't very impressed. It oscilates and you can adjust the frequency ok, but duty cycle control is very limited.
The DIY PWM Signal generator project is far more reliable. The addition of the LM393 comparator allows you to adjust the duty cycle between 0 and 100%.
You could always add this later if you are not satisfied with the performance of your current design.
CesarIII:
You make a good point. As mentioned above, additional components are needed for full control over duty cycle.
John:
It depends on your speaker and PSU. If you are using a 12V batery as your PSU, then each pulse will simply connect 12V directly to your speaker. I tried it with a big 8ohm speaker and it was pretty loud. I was able to tune it to the resonant frequency of my desk, causing everything on it to shake quite violently.
Justin:
Yes, the two resistors with arrows marked 10k, are variable resistors. The range of frequencies you can adjust the circuit over is still determined by your capacitor. |
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| CesarIII | Monday, 4th December 2006 4:50pm - No.561 |
I think we dont need the full 555 frecuency range, so extra capacitors are not neded(or necesary) in the pwm above. Which is the frecuency range the coil should work wel to give better results? Ive built some SMPS units and the usual are 22Khz to 50Khz But for what I read I think you are tryng with 2Khz. Something about??
We can switch from 12V to 24V like in a briged audio amplifier, just using 4 transistors and a SG3525 or a 555 and a CD4013. Althoug using 4013 will force the duty cycle to 50% :(
What you think? |
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| RMCybernetics | Monday, 4th December 2006 9:03pm - No.562 |
Different coils work with different frequency ranges. The larger or older ones tend not to work very efficiently at higher frequencies due to hysteresis in the large iron cores. The smaller pencil type ignition coils will work ofver a very broad range of frequencies, including ultrasonic levels, but they are usualy resin sealed and can handle less power throughput than the oil filled cylinder type. The ignition coils also have several resonant (or harmonic) frequencies which you can tune your circuit to to get maximum efficiency.
The SMPS (Switched Mode Power Supply) method can be a little more tricky with ignition coils. This is because they are effectivley autotransformers but with a very high ratio. The arcing and high voltage present at the output causes broadband RF (Radio Frequency) noise which can interfere with the correct operation of the transistors.
Anyone making this project will probably notice that the pulses to your coil are not always as regular as the signal you are sending to the transistors from the 555. This is not a major problem in this circuit, but if a bridge configuration is used, the transistors can easily be destroyed by a condition known as 'shoot through'. The is where a pair of transistors come on together (when they should not) short circuiting the input power supply through the transistors causing them to overheat. |
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| Andrew | Tuesday, 5th December 2006 12:22am - No.563 |
 OK, here is my final circuit diagram using your signal generator. I think I'll build it like this right from the start. Sorry for the plagiarism of your circuit diagram, but I am a visual person and it helps me to put it all together in one diagram like this to make sure I have everything right. If you don't find any mistakes I'll get started right away! |
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| RMCybernetics | Tuesday, 5th December 2006 1:01am - No.564 |
Looks ok as far as I can tell. I recommend you get at least one spare 393, 2n3055, and varistor, just in case :)
Sometimes the varistors fail catastrophically, and can thefore take out another component with it.
This happens because some varistors don't recover very fast, so when your transistor switches on power can be shorted through the MOV causing it to blow.
Run it for a few seconds, then switch it off and check to see if your MOV (or anything else) is getting hot.
Make sure when connecting the power, duty cycle is set to low, or zero to avoid surges. Don't turn the duty cycle up too high, it will use loads of power, but reduce the output voltage. 50% is usually suficient.
Most importantly, don't forget, high voltage devices are very dangerous and should be treated with great care and respect. Don't get complacent, always be very very careful. |
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| Crispy | Tuesday, 26th December 2006 8:15pm - No.631 |
As a follow-up on the earlier discussion about the oscilloscope trace:
I was able to obtain an oscilloscope and used it to get a trace from the ignition coil generator that I made using a similar method to what you used, but I attached an antenna to the hv output a well as the oscilloscope. The trace showed something similar to your's, but the apparent resonance was much less damped. The output waveform frequency seemed to be exactly what the input frequency was (about 1kHz) and the resonant frequency was calculated to be at approx. 6.6 kHz. Changing the antenna length on the hv side seemed to change the resonant frequency somewhat, so the antenna's capacitance might actually have something to do with the resonance. |
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| Crispy | Wednesday, 27th December 2006 12:10am - No.632 |
| And another thing, I tuned the ignition coil driver to 6.6 kHz (the determined resonant frequency of the 2 coils in anti-parallel). At this point, the trace on the scope looked like an almost perfect sine wave. I then further adjusted the frequency while it was running to get the cleanest sine wave I could. There was certainly a very large voltage spike at this point, because one of the ignition coils actually started arcing from the ground terminal, through the plastic, and to the high-voltage terminal with a bright purple arc. I need to go find some better coils with thicker cases ... any suggestions? These two are the oil-filled can type. |
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| RMCybernetics | Wednesday, 27th December 2006 12:27am - No.634 |
Justin:
A diode is usually placed in parallel with the transistor like shown in the top schematic on this page.
While this may reduce the risk of blowing a 2n3055, it cannot guarantee full protection. There are many possible reasons for transistor failiures in inverter circuits like these.
Crispy:
Somtimes people place ignition coils in a container filled with oil. This helps prevent arcing from the ignition coils terminals.
There's a huge numer of coil types available, ask at your local auto spares shop to see what's available. |
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| stef22 | Saturday, 30th December 2006 8:42pm - No.649 |
Hi,
I've built the circuit shown on this page. when i used it worked all right. then some time later(2 weeks) it seemed like the output lost a lot of its power. I used it with a high voltage diode in series with its output to charge capacitors with a spark gap in parallel with them as to charge and discharge with pulses. now to even charge a capacitor i have to arc the high voltage to the capacitors because if i connect the wire to the capacitor the ignition coil loses all its power.
Do you have any ideas on what's going on and how can i fix it? |
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| RMCybernetics | Monday, 1st January 2007 4:04am - No.653 |
I suspect it's likley to be one of two things...
1. Faulty 2n3055 transistor. These can fail in a wide range of ways. The most common transistor failiures cause it to latch on or off, but somtimes they can be only partially damaged, giving symptoms like you describe.
2. Faulty HV diode. In the same way as above, a diode can be just partially damged.
These sorts of intermittent or partial faults are caused by exessive voltage or current surges in the circuit.
This post may help you find more info. |
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| jay | Friday, 5th January 2007 4:40am - No.681 |
| hi im planning on making high voltage through a fly back transformer but iam lousy with electronics. could i just disconnect the high voltage out put of the fly back from the cathode ray [tv] and use that with out any advance circuitry. |
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| RMCybernetics | Friday, 5th January 2007 10:14am - No.683 |
Yes, this is a common method used for powering electrohydrodynamic thrusters known as lifters. The output from this lead is High Voltage DC.
Please be aware that the output from this terminal is highly dangerous and quite deadly. Even when switched off a capacior inside can retain a lethal amount of energy. Never put your fingers anywhere near the HV output terminal (even if the TV is unplugged). Don't take any risks with these things, they can kill. |
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| RMCybernetics | Friday, 5th January 2007 1:29pm - No.685 |
Jay, my last message was a reply to your question regarding using the output from a TV flyback transformer.
I expect that if you were to arc from this output to a small piece of tin, it would begin to melt the tin. The plasma temperature in the arc would be very hot, but it would draw more current from the transformer than it is designed for. The positive HV DC output is only used to create an electrostatic attraction between the moving electrons (cathode rays) and the inner surface of the screen. Making arcs (which is neccesary for the high temperatures) is effectivley a short circuit accros the transformer output.
The transformer will prrobably survive this sort of treatment if it is just intermittent, but if switching transistor is used for controling power to the coil, it will overheat and blow in a relativley short time.
Also the output of the transformer is rectified (converted to DC) by a voltage multiplier. The diodes in this may also be damaged by too much current.
You can limit the current (but thefore the temperature) drawn by your arcs by placing a large resistor in series with the output. If you don't have such a resistor, a length of carbon may suffice. |
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| justin | Wednesday, 10th January 2007 3:25pm - No.690 |
i made the circuit posted diagram at the top and i should have listened to your advise rmc because it took two hours to build and 5 seconds to blow on my coil the tlc 555 comos timer cracked and gave off the death of circuit smoke.
dose your design handle T waves[rmc]
whats the signal generator |
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| RMCybernetics | Wednesday, 10th January 2007 5:19pm - No.691 |
Bummer, I think anyone who has made an ignition coil driver (including myself) has had similar experiences. It's always good to learn from experience though, allthough it can get expensive!
The top diagram which shows RC1 will be more stable, but it can still be blown quite easily when the output is pushed quite high. The 555 timer circuit you used has a very limited range of adjustment for pulse width (duty cycle). It stays around 50%, which is quite high and will create a lot of back EMF spikes.
The PWM signal generator has a fully adjustable duty cycle so you can adjust the power more precisley and keep it below 50%.
Obviously putting less power in, means you get less HV power out of your coil, but there is always a compromise to be made somewhere in electronics design. Running at lower power levels means that components are less likley to be destroyed, but there is still no guarantee. Making High voltage sparks from low voltage DC sources is often problematic.
There are also several other methods for protecting your components from the spikes. Have a look at Andrews posts above. This link discusses various methods for protecting against surges from inductive loads. It's targeted for relay switching but the principles are the same. |
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| justin | Friday, 26th January 2007 4:01am - No.723 |
| could you use a circuit like this to power a fly back transformer. and would this transformer be a lot more stable to use on the circuit? |
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| RMCybernetics | Friday, 26th January 2007 2:27pm - No.724 |
| You can drive almost any transformer with this circuit. How well it works will depend upon the transformer, but it will need to have a reasonably low input impeadance. A flyback may be a little more stable than an ignition coil, but if there is no load on the output you will still get some spikes induced back into your low voltage circuit. |
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| RMCybernetics | Tuesday, 13th February 2007 5:56pm - No.761 |
The resistors are all the standard 0.6W type. The capacitor voltage rating simply need to be anything higher than your supply voltage.
All the other components are listed at the top of the page.
If you are wanting to make long sparks, then I would reccomend using a different circuit. The best one would be the Pulse controller. |
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| JohnnyMac | Thursday, 15th February 2007 6:23am - No.769 |
I am going to start rounding up parts for my project. My questions are is the second curcuit less prone to blowing transistors due to the lack of a shared ground with the high voltage?
Can higher current power Mosfets be used in this curcuit?
Is there a limit on the number of Mosfets? Possiblly with a seperate Mosfet board/unit with enough cooling could this control 80A+ electric motor, or course with protection. Mosfet ex: HUF76145P3, High Current MOSFET, N-Channel, Enhancement Mode, 75A, 30V. Ebay of course. Thanks John
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| RMCybernetics | Thursday, 15th February 2007 10:00pm - No.775 |
JohnnyMac:
The antiparralel inition coil setup actually seems to be more likley to blow transistors when its not loaded. If the output is loaded, then there is usually no problem. The transistors are exposed to HV spikes mostly when the circuit is being used for making sparks.
Higher powered mosfet will work, but mosfets require a higher gate/base voltage to switch them. If your DC source is 12V then this should be no problem. The gate pin of mosfets is like a capaciative load so there should be no problem driving large mosfets. If you are looking to control a motor, then I would recommend this circuit.
Problematic:
100R just means 100 Ohms. The R is often used where the decimal point would be. eg. 2R2 = 2.2 Ohms, 4k7 = 4.7k (4700) Ohms.
The way you have shown VR1 would just give the same resistance all the time. You need to use the centre pin and one outer pin.
Your question regarding the 2n3055 pinout has been answered previously. Check the post dated 3rd December 2006 4:45pm. |
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| RMCybernetics | Friday, 16th February 2007 1:35pm - No.778 |
 No probs, thanks for sharing.
I've modified your diagram to show the pinout of the 2n3055. The 2 pins under the 2n3055 are actually offset slightly to one side. It's not clear from that previous datasheet, so try this 2n3055 datasheet. You'll need to scroll down to page 4.
I've not used a multimeter to find the pinout before because I have one of these very handy component analysers. I suppose you could use the diode test mode. You should see a low resistance between base and emmitter if the +ve lead is on the base pin. It shouldn't conduct the other way around, but don't hold me to that, I've not tried it! :) |
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| Problematic | Saturday, 17th February 2007 12:21pm - No.783 |
 For those who wanted to know how to connect the BFY51, look at the image attached to the comment. Thank you :D |
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| RMCybernetics | Monday, 19th February 2007 11:08am - No.790 |
The IC's blow usually because of high voltage spikes in the low voltage circuit. A snubber like RC1 in one of the top diagrams may help. Also adding a large capacitor in parralel with your battery supply can smooth the voltage. There's also several other methods. Its all too easy to blow your low voltage components when driving ignition coils unfortunatley.
If the capacitors you placed on the output are not specifically rated for high voltage, then they will certainly get melted. |
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| abdia | Friday, 9th March 2007 8:07am - No.863 |
| if i use one ignition coil ,what is max sparks length from this coil that i can get?and what is max sparks of your circuit(2 ignition coil)? |
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| RMCybernetics | Friday, 9th March 2007 11:21am - No.867 |
| It is highly dependant upon the ignition coil you use. There are 100's of types. Typically from a 12V source with a circuit like the one above, the sparks will be upto 5cm. |
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| hv man | Tuesday, 13th March 2007 9:33am - No.887 |
dose a mot transformer 'microwave oven transformer' have a high frequency out put?
even if it dosnt i can use it on my ignition coil because the coil would act as a resistor draining power from the capacitor as it cahrges causing a pulse, im not to sure but that is my theory. would this be right or wrong? |
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| RMCybernetics | Tuesday, 13th March 2007 10:45am - No.888 |
An MOT is designed to work at 50Hz or 60Hz from a typical mains outlet. it may work at highr frequencies, but I don't know how well.
I don't understand what you are trying to do with your ignition coil and capacitor. Please explain in more detail if you want more help. |
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| hv man | Friday, 16th March 2007 6:36am - No.898 |
| for a 555 timing circuit dose it matter on the type of transistor that is used for example a 2n3055 transistor replaced by a bd243c or etc im not sure so i need you to repli soon please im working tonight.? |
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| RMCybernetics | Friday, 16th March 2007 10:26am - No.900 |
| Yes most bipolar transistors will work fine. |
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| Chules | Wednesday, 28th March 2007 7:38pm - No.1001 |
Hello,
I have a few questions about these ignition coils and drivers in general, and was wondering if anyone here could answer them. First, it is my understanding that the high voltage output of an ignition coil is produced in part by the voltage produced across the inductor as a result of the square wave with the equation (e = L(di/dt)). Is this correct? Also, if this is correct, it seems that a perfect square wave would produce an infinite voltage across the inductor, but this is obviously not true. Why is this? Also, is the peak voltage mathematically predictable or is it entirely due to stray resistance and/or inductance? Also, what kind of voltage could I expect to get out of the ignition coil if I ran it with a sine wave instead of a square wave, using it as a normal autotransformer?
I'm planning on trying to build a HVDC power supply based on ignition coils. Most such designs use a bridge rectifier and a smoothing capacitor. With ignition coils producing very short peak voltages, wouldn't the ripple be significant unless a very large smoothing capacitor was used? And is there any way to decrease/prevent this ripple other than by using such a large capacitor?
Thanks,
Chules |
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| RMCybernetics | Wednesday, 28th March 2007 9:04pm - No.1003 |
The equation you mention is for a perfect inductor. This means that it would have no resistance and no capacitance. There is simply no such thing in any practiacl sense.
Your question about a true square wave causing the voltage to rise to infinity is a good one. This would be true if it were possible to instantly stop the curent flowing in the inductor, but because of several factors, this can not happen.
The wire that makes the coil obviously has some resistance, but this is not our main concern because we allready know that superconductors having zero resistance are possible. Assuming we have eliminated all resistance from the coil, we are now left with inductance and the self capacitance of the coil. The self capacitance is a product of the seperate coil windings and the voltage difference between them. This capacitance is only very small, but it is plenty enough to prevent the voltage rising to infinity. A capacitor has an associated time constant which means it will take a finite amount of time to charge or discharge. This prevents any instant change of current in the coil and therefore limits the voltage rise produced.
The output votage is calculable, but it can get tricky to account for all the factors, especially when some of the values are not known.
If you use a sine wave then the dI/dt will naturally be smaller and therfore will give a lower output voltage. You would need to se a higher voltage sine wave to get the same output voltage as you would from a low voltage square wave.
With a square wave input the ripple is likley to be significant so a large capacitor is often the only solution. Alternativley combinations of capacitors and inductors can help smoth it out.
If the coil is driven at resonance, the output voltage will be higher and the waveform more sine like. |
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| EE | Thursday, 12th April 2007 11:26pm - No.1145 |
i admire your work and your knowledge. So that leads me to ask you your advice on building a 6 volt electric fencer using a 6 volt car coil,solar powered to keep the battery charged, using ne555 timer,3055 transistors. i was wondering if you had any ideas for pulsing the coil correctly?
Thank You,
EE |
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| RMCybernetics | Friday, 13th April 2007 2:13am - No.1146 |
Using this circuit with a capacitor of about 1uF for C1 will give DC pulses every second or so. To avoid saturating the transformer core you would need to set the pulse width very low by adjusting VR2.
A snubber circuit of some sort would probably be needed to stop high voltage spikes damaging the ICs. Just placing a capacitor across the coils input terminals would help but it would also reduce the output voltage by a small amount. |
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| Kenny | Thursday, 10th May 2007 6:21am - No.1246 |
| I have a question im going to use 2 ignition coils in series for more current to power a tesla coil, since the ignition coils work on square waves and the secondary of the coils turn on and off many times a second they already have a rising and collapsing field so would i still need a high voltage capacitor connected in the primary cicuit of the tesla coil? |
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| RMCybernetics | Thursday, 10th May 2007 11:04am - No.1247 |
You will need to connect ignition coils in parrallel for more current. See this post.
The primary capacitor in a TC is essential as its value determines the resonant frequency of the system. |
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| Kenny | Friday, 11th May 2007 7:57am - No.1253 |
| Hello Is there a way to hook up my coils to get more voltage that won,t damage the coils? since anti parrallel destroys the coils eventually,(Thanks for telling me that). The circuit im using works on Ac,i would like to use Dc but its to complex for me, and thank you for the parrallel diagram it works good for more current. |
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| RMCybernetics | Friday, 11th May 2007 2:07pm - No.1254 |
It's the extra high voltages and running coils with no load (nothing on the output of the coil) that leads to failiure. When the voltage is very high and there is no load attatched, the internal insulation can break down leading to a short circuit. Oil filled coils may last a little longer because the oil acts as a 'self healing' dielectric, but the performance will certanly degrade over time.
The peak output voltage you can get from a coil is determined by the input voltage and the rate of change of curent (dI/dt). Since the dimmer has total control over dI/dt and the input voltage is always at mains level there is not much you can do.
If a DC output is ok, then you could use the ignition coil to drive a voltage multiplier for increased voltage. |
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| Ken | Thursday, 17th May 2007 6:09am - No.1282 |
| I have a neon sign transformer rated at 15000 volts at 30 millamps i use it for a Tesla Coil,is the current of 2 ignition coils in parallel close to or higher then 30 millamps? witch would work better for the TC? I want to use the ignition coils so i don,t have damage to the NST,also my Capacitor is a salt water capacitor it works poorly how could i make a better cap or buy ones that would work?,Do ignition coils have current limiting like a NST? do you know where i could get RF chokes to protect my Neon sign Transformer? Thank you very much. |
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| RMCyberentics | Thursday, 17th May 2007 7:24pm - No.1289 |
Ignition coils will not come close to the power output of your NST. They do not have any current limiting built in. It is common to drive them through a large power resistor of a few ohms.
For a saltwater cap the water needs to be saturated with salt (no more will dissolve). Also avoid aluminium as the electodes as the salt water will cause them to oxidise on the surface and give poor conductivity.
You can find the HV caps and RF chokes on eBay. |
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| artemoonlv | Monday, 28th May 2007 6:39pm - No.1348 |
| Why do we need pre-amplifying transistor? BFY51? why we cant just send signal directly to the 2n3055? |
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| RMCybernetics | Tuesday, 29th May 2007 10:41am - No.1350 |
JimmyFromAus:
You seem to be missing the point. People are here and asking questions so they can learn new things. Were you somehow born with the knowledge you have?
artemoonlv:
The 2n3055 needs a resonable current for it to switch. Unlike a MOSFET, these often need more current than an IC (like a 555) can supply. |
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| kenny | Thursday, 7th June 2007 6:10am - No.1376 |
| Hello i enjoy (trying) to make all kinds of high voltage devices my last was the dimmer capacitor and ignition coil, what i wanted to know is could i use the same circuit i used to power the ignition coil to power a Flyback transformer? or is there a (very simple circuit) i could make to power the flyback i want to have high frequency electricity i can,t get that from an ignition coil......thanks |
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| RMCybernetics | Thursday, 7th June 2007 10:45am - No.1377 |
The dimmer circuit is limited to a low frequency modulation of the mains frequency.
You will need a circuit designed for higher frequencies if this is what you need.
Our Power Pulse Modulator will drive flyback, ignition coils and almost anything else. The frequency is adjustable so you can set it to whatever works best. |
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| c1vt3gr4 | Thursday, 12th July 2007 8:41am - No.1431 |
sorry to ask this but i am very new at this so here i go. i just wanna know what is the input signal for on T1 and what do you hook it up to?
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| RMCybernetics | Thursday, 12th July 2007 9:19pm - No.1434 |
 The power to the ignition coil needs to be switched on and off repeatedly. By applying a square wave signal from a signal generator, the transistors will switch the large currents for the coils on and off in time with the signal.
A common signal source is based on a 555 timer like this DIY signal generator.
You can also buy such a circuit with the signal generator, power transistor and added transient protection in our Cyber Circuits shop. |
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| Milos | Sunday, 22nd July 2007 12:57pm - No.1489 |
 Hi,
can I use this circuit to drive ignition coil ( with
RC1 and diode for protecting 2n3055 )- to have one battery for oscillator and to have an other for induction coil?
Many Thanks!!! |
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| RMCybernetics | Sunday, 22nd July 2007 2:32pm - No.1490 |
| Yes you can. You may need to adjust the values of RC1 to better match your coil. |
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| Deda Raca | Wednesday, 1st August 2007 5:01pm - No.1525 |
Is more current from power suply means longer sparks ( about 18 or 24 Amps )? I will use it to power Tesla Coil.
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| RMCybernetics | Wednesday, 1st August 2007 5:09pm - No.1526 |
Not directly. More input power will give longer sparks as long as it is not wasted in the circuit somewhere.
Increasing the voltage applied to the ignition coil wlll mean that it will draw more current, but it could just be wasted if the core is becomes saturated (can't contain any more magnetic flux). |
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| venu | Friday, 3rd August 2007 6:57pm - No.1529 |
| how can i get a DC HV output from this ignition coil driver?if possible please provide me a circuit.And also please provide me a 0-30v 3amps variable simple low cost dc power supply unit circuit diagram for my experiments. |
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| RMCybernetics | Saturday, 4th August 2007 7:31pm - No.1536 |
The simplest way to get DC is to connect a high voltage diode in series with the output.
Using a power pulse modulator set to high frequency and with a smoothing capacitor in parallel with the output will serve as an adjustable switch mode power supply. |
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| Josh | Saturday, 4th August 2007 11:49pm - No.1538 |
| Okay the circuit is sinple enoguh but for the signal could I just use a switch and a small amount of power to trigger the spark then after that build the 555 circuit ? Otheer than that I'll put it on a perf board and I think it will work. |
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| venu | Sunday, 5th August 2007 8:09am - No.1539 |
| with 12v dc how much current in amps is given as input to this ignition coil driver? |
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| RMCybernetics | Sunday, 5th August 2007 1:15pm - No.1540 |
Josh:
You may be able to get single sparks if you can press and release your switch fast enough. It would be pretty easy to burn out your 2n3055's like that though.
venu:
It is totally dependant upon your loads impedance. You can calculate the current using ohms law.
Driving a common cylinder type ignition coil at its resonant frequency from 12V will typicaly draw about 5 amps. |
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| will | Tuesday, 7th August 2007 9:10pm - No.1547 |
| would putting 2 ignition coils in parallel double the output current or the output voltage? |
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| RMCybernetics | Tuesday, 7th August 2007 9:56pm - No.1548 |
| Double current from parallel coils. Double voltage for 'anti-parallel' as shown in the lower diagram |
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| Kevin | Saturday, 18th August 2007 6:38am - No.1616 |
| Hello I have made a ignition coil driver that works using a dimmer switch and a 7.5 uf capacitor it uses 110v Ac. I noticed when the coil was operating that a lamp that was pugged into the wall was flickering on and off very fast the switch on the lamp was off, im getting feed back into the house. I have the high voltage output set to arc to the negative terminal of the coil, is that putting feed back into the house if so how can i change my set up to stop high voltage feed back, the lamp no longer works i tried a new light bulb, its fried. |
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| kevin | Saturday, 18th August 2007 7:01am - No.1617 |
| My ignition coil driver uses a 7.5uf capacitor for current limiting, i also have a 4.0uf capacitor, each capacitor has two terminals each. they were expensive and i want to know if there is a way i can hook them together to get more current to the coil if so i could get 11.5uf i want to ask before i try connecting them together because i think that since the one cap is bigger then the other its charge will destroy the smaller capacitor. |
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| RMCybernetics | Saturday, 18th August 2007 6:50pm - No.1620 |
You need a device known as an RF choke or an EMI filter between your mains outlet and dimmer circuit. You can find these on eBay.
Connecting your capacitors in parallel will not cause problems if they both have a suitable voltage rating. |
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| jeff | Sunday, 26th August 2007 7:55am - No.1656 |
| Hello, some ignition coils have an internal resistor others have no internal resistor witch coil is better to use for an AC ignition coil driver? Also is a ignition coil off a v8 engine give higher voltage then one from a six or four cylinder engine? |
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| RMCybernetics | Monday, 27th August 2007 11:08am - No.1663 |
| The internal resistor is for limiting the current in the coil to prevent damage. If the ignition coil is designed to fire more spark plugs at once, it is likley to be able to deliver more current. You would have to treer to the manufacturer for more specific details. |
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| mark | Wednesday, 29th August 2007 7:07am - No.1671 |
| I would like to increase the frequency of the high voltage output of my ac ignition coil driver. is there a way to make and attach a device on the secondary of the ignition coil to get a higher frequency voltage? |
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| RMCybernetics | Wednesday, 29th August 2007 6:44pm - No.1675 |
| Not practically. You need to use variable frequency source on the input. |
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| THE_KID | Sunday, 2nd September 2007 4:48pm - No.1685 |
Hello,
i got 12 2n3055 transistors on large heatsink. I noticed that they are not equally heating. One is very hot and some are cold or warm. What can I do to fix this?
Many thanks!!!1
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| RMCybernetics | Sunday, 2nd September 2007 9:06pm - No.1686 |
| Small differences in the performance of each 2n3055 can cause this sort of effect. The hot one is probably partly damaged and not switching on fully. A higher voltage on the base pins may also help ensure the transistors are fully switched. |
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| venu | Saturday, 8th September 2007 7:59am - No.1693 |
| difficult to find BFY51 transistor,is there any substitute.For 12v power supply battery how much amps battery is used. |
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| RMCybernetics | Saturday, 8th September 2007 4:56pm - No.1695 |
| Any similar npn bipolar transistor will do the trick. The current drawn depend upon frequency, load etc but is usually around 5A. |
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| Echbert | Monday, 10th September 2007 7:58am - No.1697 |
How long can this thing work Continuously? Will the coil not overheat??
Thanks your circiut works perfectly! |
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| RMCybernetics | Monday, 10th September 2007 1:54pm - No.1700 |
It depends on the manufacturers specs for the ignition coil used. I would expect that under heavy load with large current draw the coil could eventually overheat.
The output voltage will depend on the specs for your specific coil. It averages around 20kV |
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| Sam | Monday, 24th September 2007 2:30pm - No.1746 |
Can one of these circuits be used in place of a regular auto ignition system -
e.g. - Have the HV generator running constantly and switching the HV to multiple spark plugs (according to ignition timing) via some thyristor.
or - Have multiple HV spark generators (one for each set of spark plugs) and turn them on/off according to the ignition timing.
For a 4 cylinder engine - 4 sparks per revolution @ 750(min)/8000(max) RPM -> 3000(min)/32000(max) sparks per minute -> 50(min)/534(max) sparks per second or Hz......
In theory "arc" ignition sounds better than spark ignition......
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| alan swane | Monday, 24th September 2007 3:01pm - No.1747 |
dear rmc
im interested in musical tesla coils but need some background information first: for a solid state tesla if you use say a simple design like the self resonating flyback could you just add the music input into the feed back wires to switch to the frequency of the musci? thank you for your help. |
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| RMCybernetics | Monday, 24th September 2007 3:52pm - No.1748 |
Sam,
They have not been designed or tested for use with engines, but the circuit does drive auto ignition coils. Your suggestions seem sound, but I couldn't comment on the effectiveness of an arc ignition compared to a spark ignition.
alan swane,
It may be possible to do it like that but I would excpect a lot of distortion in your input signal caused by the feedback/self resonanting system.
The best way is to drive the HV supply (a flyback or TC) at a set frequency which is high enough to be inaudiable to humans. This signal is then amplitude modulated with the audio signal which you wish to hear.
For example; you have a driver like on this page driving an ignition coil at a set frequency. You would disconnect the signal from the base pin of the 2n3055 (or equivalent) then connect it to the collector of another transistor (such as BFY51). This transistors emitter pin would then go to the base pin of the 2n3055s. You can now add your audio signal to the new transistor. The audio signal would dynamicaly alter the resistance of the transistor so that the power level of the drive frequency becomes proportional to the audio input. Of course there may be a need for a few R's and C's to keep the voltages in your circuit correct. Now any arc could easily be modulated with audio. |
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| alan swane | Tuesday, 25th September 2007 12:30pm - No.1753 |
| could you please post a simple design its hard to understand in words lol sorry , i am good at electronics but i cannot make the connections in my head. |
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| RMCybernetics | Tuesday, 25th September 2007 12:57pm - No.1754 |
 The diagram just shows the basic components. You will still need to add things like RC1 and a diode.
this diagram shows how a BFY51 transistor is used like a switch or valve for controling how much of the HF (high frequency) signal is allowed to get to the power transistor.
With 0V placed on the modulation input, the HF signal will be blocked and thefore the power transistor will not switch on. When some voltage is applied to the modulation input, the HF signal can pass through and drive the power transistor. The level of the HF signal reaching the power transistor will be proportional to voltage applied to the modulation input. Therefore if the modulation input voltage is varying with time, the output power of the ignition coil at the HF drive frequency will vary with it. |
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| alan swane | Wednesday, 26th September 2007 1:40am - No.1756 |
| i get how it works but what is the HF drive signal and were does the second audio input go sorry baout all this but thanks again for the help. i was planningon using a self resonating design could this be impamented some how thanks. |
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| RMCybernetics | Wednesday, 26th September 2007 10:40am - No.1760 |
The HF signal is a single frequency square wave from a 555 timer or any other signal generator. This is what you have in a typical ignition coil driver to make your arc. You then modulate this arc with your audio.
What second audio input? |
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| Bob Dole | Thursday, 27th September 2007 8:31pm - No.1769 |
| Hello. Would it be possible for me to replace the BFY51 Transistor with a 3904? Also, I see that under the parts list it says "2n3055 Power Transistors". Is this a typo or are there actually two of these transistors [I can see only one in the schematic]? Thanks for the help. |
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| RMCybernetics | Thursday, 27th September 2007 10:40pm - No.1770 |
Yes, almost any npn transistor will work if it rated for the voltage you use.
Two or more 23055s can be placed in parallel to allow for more current. |
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| RMCybernetics | Saturday, 29th September 2007 1:13pm - No.1780 |
When a single wire is shown like this in circuit diagrams it represents a signal/voltage with respect to ground. This means that if you are connecting two circuits together (your audio source and the coil driver), there must be a common ground between them. A common ground is created by simply connecting the ground point of one circuit to the ground point of another circuit with a single wire.
I can only guess that one of the wires in your pair is ground, the other will be signal.
Like I already mentioned, I don't think this will work properly with a self resonating design. The frequency generated by the self resonating circuit is equivalent to the HF drive signal, but if you start trying to modulate this the feedback loop will become unstable and therefore cause the drive frequency to change. |
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| Albert Como | Monday, 1st October 2007 12:30am - No.1783 |
I built a very similar circuit myself. The only differences though is that is uses only 1 2N3055. and instead of a BFY51, I'm using a TIP3055. I'm only getting 1 cm arcs. This is supposedly a 42000 volt ignition coil.
I wondering what you think the problem is. I think that I need to switch the TIP3055 with something faster. The TIP only does 3MHZ. I don't have a BFY51. Could I just get a few fast, low current transistors and hook them up in parallel to meet the current requirements? Do you think that a faster switching transistor would solve my problem? |
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| RMCybernetics | Monday, 1st October 2007 2:19pm - No.1784 |
Placing transistors in parallel theoretically will give you more current handling, but it only works to some degree.
Each transistor will switch at very slightly different times due to manufacturing tolerances. This has two major drawbacks in this application.
1. If the peak current exceeds the capacity of a single transistor, the first one in the array to switch on is likely to get destroyed. With many cycles happening within a second you can blow several transistors quite easily.
You can prevent this from happening by placing a current limiting resistor in series with each transistor. This will protect the transistors but it is not efficient because a lot of heat is generated when the high current flows through a resistor. One reason multiple transistors are used here is to reduce the total 'on resistance' which allows more current to the coil.
2. The output voltage of the coil is proportional to the rate of change of current in the primary coil. With an array of transistors, they are not switching together so this rate of change is reduced slightly. The added junction capacitance also increases the time it takes to switch off.
The TIP3055 does switch off pretty slowly compared to the BFY51 (1us vs 60ns). You probably don't need a preamplifying transistor anyway if you are using just one 2n3055.
To get the full output of your ignition coil you must ensure the transistor is switched fully on before it is switched off, and you must switch it off in the shortest time possible. |
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| Karl Riemmann | Tuesday, 2nd October 2007 12:11am - No.1791 |
A small note on the RC component of the circuit. The effectiveness(ability to produce sparks) is reduced with the exclusion of the R from the RC filter since this effectively defeats the switching function of the transistor.
In fact, the resonant frequency generally increased with increasing resistance. This seemingly paradoxical behavior is due to the non-linear character of the diode.
Just a small note... |
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| alan swane | Tuesday, 2nd October 2007 5:42pm - No.1808 |
| would a typical head phone port be enough power to switch the byf51 transistor and when you state the resistors and diodes could you please state the values i havent advanced this far lol your too smart for me i dont get some of the basic stuff lol love this site very unique |
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| RMCybernetics | Tuesday, 2nd October 2007 5:54pm - No.1809 |
More than enough. You will probably need 1k of resistance and about 1uF capacitor in series. The resistor will prevent the transistor from blowing and the capacitor will block DC. Start on a very low volume to test things out. I would also reccomend replacing the ignition coil with a speaker while you get it working.
Also don't use your PC or anything expensive as your audio source if you are modulating an ignition coil. There is a high risk that you will damage your source.
Look for info on optoisolators for keeping your audio source electrically isolated from your HV circuit. |
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| Albert | Wednesday, 3rd October 2007 7:28am - No.1815 |
| What's the difference between anti-parallel and series? |
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| RMCybernetics | Wednesday, 3rd October 2007 2:42pm - No.1820 |
 Antiparallel refers to placing polarized (has a + and -) component in parallel but with the opposite polarity to each other. |
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| Albert | Thursday, 4th October 2007 5:01pm - No.1828 |
Why does antiparallel double the voltage when parallel doubles the amps?
Is the output the two output terminals connected or does the spark jump between the coils? |
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| RMCybernetics | Thursday, 4th October 2007 8:14pm - No.1830 |
Anti-parallel will cause the output voltage to be of the coils to be equal and opposite (when one is +10kV the other is -10kV). The spark would jump between the two output terminals. The two output voltages are considered to be 180 degrees out of phase.
When in parallel the outputs are in phase. This means that the voltage between the two outputs will always be zero. If the outputs are connected together they will operate as a single ignition coil would but with the potential to deliver 2x the current. |
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| Bob Dole | Friday, 5th October 2007 5:42am - No.1837 |
| I don't understand why there is a 3-way switch. Shouldn't there just be a simple on-off switch? |
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| Bob Dole | Friday, 5th October 2007 5:59am - No.1838 |
| Does the ground on the first schematic connect to the "side" of the light bulb? Also, I am using the dead bug signal generator. Does it require its own 9v battery for power? I've set up the project on a breadboard and tested it out. So far nothing has happened. I disconnected the light bulb and help a screwdriver in the HV output of the ignition coil, and no spark appeared. What possible issues should I be looking for, other than the basics? Your help and website is much appreciated. |
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| RMCybernetics | Friday, 5th October 2007 1:16pm - No.1843 |
The switch allow you to select 12 or 24 V operation.
What light bulb?
The signal generator can have its own battery or just run from the same source as the coil |
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| Bob Dole | Saturday, 6th October 2007 5:41am - No.1849 |
| Oh sorry, I've hooked the HV output up to a light bulb to create [hopefully] a plasma globe. The terminal on the bottom of the lightbulb is connected to a spark plug wire connected to the HV output, and I have part of the light bulb that actually screws in connected to the ground of the driver. Is this right? |
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| RMCybernetics | Saturday, 6th October 2007 6:07pm - No.1854 |
Nope. You have a couple of things wrong. Don't use the spark plug cable. It uses a carbon based material for the conductor which has a high resistance. You need to use a normal wire with a metal conductor.
The light bulbs electrical connections should be shorted (linked together), then a single wire from this should be connected to the HV output of the ignition coil. This makes the fillament inside the bulb at a high voltage compared to the ground (and surrounding objects). The plasma filaments will reach out for grounded objects placed near to the bulb.
It's best to keep HV wires as short as possible so that energy is not lost to the surrounding air. The best way to connect your bulb is to stick it right onto the output of the ignition coil with some wire or foil inside to make the connection (like this). |
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| kerk man red | Sunday, 7th October 2007 5:19pm - No.1860 |
 dear rmc with your ignition coil plans at the top i have most of the components but have a couple of questions: will any npn transistor drive the 2n3055 transistor provided within the voltage range?'meaning tolerance' and will any diode say about a 6 amp diode work on this circuit instead of the one posted? thankyou for your help i plan on making a wave generator that can sweep up to 10khz to 100khz and i wanted to know if i could find resonace of my coil withing these ranges thankyou so very much i love this site only one like it around keep up the good work. |
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| john redcorn | Sunday, 7th October 2007 8:09pm - No.1861 |
| dear rmc i just made the circuit that you have posted up the top and it works but i noticed that when a dc signal is applied the oscilloscope shows that very same signal been interupted is this normal. i also wanted to know that if i apply a 9v signal what resistance should i use so i dont blow the npn gate transistor'byf51' im not sure but i think it only needs about 3 to 4 volts to drive it but i have no clue as to what resistor i should use. thankyou for your help it will be much appreshiated , i should use a varible resistor in case of different applications |
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| Albert | Monday, 8th October 2007 1:49am - No.1863 |
Alright. Hopefully my last question. I have 3 different coils. They are all different types. Will hooking two of these up in anti-parallel work, or will their frequencies be messed up or something?
And can I do a set up where I have 2 parallel sets of coils hooked up in antiparallel? (4 coils. 2x voltage. 2x current) |
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| RMCybernetics | Monday, 8th October 2007 1:36pm - No.1866 |
Different coil types will not work so well together. Each coil will have a different resonant frequecy at which it works best.
Yes you can, if they are all the same model coil. |
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| Bob Dole | Monday, 8th October 2007 11:18pm - No.1874 |
| How can I test the circuit to see if it is producing an HV output? |
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| RMCybernetics | Tuesday, 9th October 2007 12:46am - No.1875 |
kerk man red,
Yes most npn transistors will work if it has similar current and voltage ratings.
john redcorn,
100 ohms is still ok for 9V.
Bob Dole,
A neon or fluorescent light will glow when connected to the HV output |
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| Bob Dole | Wednesday, 10th October 2007 12:39am - No.1885 |
| What is the common ground? |
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| Albert | Wednesday, 10th October 2007 2:50am - No.1887 |
The 555 is fried when ever I bring the voltage over 11 volts. With or without the coil.
Is is possible to run the signal generator off of a separate 3v source and run a full 12 through the 2N3055? |
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| RMCybernetics | Wednesday, 10th October 2007 11:45am - No.1890 |
Bob Dole,
Common ground is just a connection between the ground, 0v, or -ve terminals in seperate circuits. e.g. To connect a signal source with a 9V battery to the ignition coil driver a wire is connected between -ve terminal on the 9V battery and the -ve terminal of the 12V battery. This is your common ground. You can then connect the signal output of 1 circuit to the signal input of the other.
Albert
Yes, See above. It should not fry on 11 V. You probably just need to limit the current with a 100 R resistor. |
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| Albert | Wednesday, 10th October 2007 6:55pm - No.1909 |
Where do I put that 100 ohm resistor? On pin 1 or 8?
On the connection to the comparator? On the whole circuit?
Can I have a voltage regulator chip on the VCC of the 555? |
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| RMCybernetics | Wednesday, 10th October 2007 8:01pm - No.1911 |
| Either pin, but it is most often placed between +ve and your device. A Voltage regulator would be better. |
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| Albert | Wednesday, 10th October 2007 9:35pm - No.1913 |
Wait, you mean put in on the pin 1 or 8?
Or do you mean in series with the ignition coil? |
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| IM | Friday, 12th October 2007 1:27am - No.1934 |
Would it work to run an ignition coil directly off of a 12v power supply for spark gap experiments, or would the voltage that occurs on the primary side of the coil when it is discharged be likely to cook the power supply? I've emailed a couple of people about this question, but haven't gotten a response.
Thanks a lot for your help. |
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| RMCybernetics | Friday, 12th October 2007 1:33am - No.1936 |
| Your supply is likely to get damaged unless you are able to suppress the voltage spikes effectively. |
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| Tim | Friday, 12th October 2007 4:41pm - No.1941 |
| How significant is the danger from this driver when used to create a plasma globe? |
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| RMCybernetics | Friday, 12th October 2007 4:47pm - No.1943 |
Danger of what? Fire, electric shock, RF interference?
If there is no mains voltage and no HV capacitor on the output, then the electric shock is unlikely to kill directly. It could still make you jump or cause muscle reflex which could indirectly hurt you or someone else.
If all metal parts are insulated and the coil is running at high frequency, then there is little danger from touching the glass.
You still need obvious safety measures like making sure things aren't getting hot or internally arcing. |
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| ronald | Sunday, 14th October 2007 1:43am - No.1951 |
| you know that driver circuit you have posted at the top well i noticed a square wave effect when the input signal wires were crossed. if you have a relay in series with a 1k varible resistor could you use this as you signal supply 1k been the frequency conroller. please relpy soon. |
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| RMCybernetics | Sunday, 14th October 2007 12:47pm - No.1953 |
| There is only one input signal wire. How is crossed? A relay is a switch, not a signal source. They can be wired to oscillate though, is this what you have done? |
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| ronald | Tuesday, 16th October 2007 10:03am - No.1963 |
| not yet but i have a square wave for some reason the second wire is ground lol thats what i meant i just need a simple driver to run my tc that has a long life because all my other drivers have a classical fait after a 1 min run |
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| RMCybernetics | Tuesday, 16th October 2007 1:21pm - No.1964 |
| I'm not sure how you are getting this square wave. Ignition coil drivers are prone to failure unless careful attention is paid to reducing back emf. The article above has been updated with a little more info regarding this. |
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| Kevin A | Tuesday, 16th October 2007 7:54pm - No.1965 |
| Do the grounds from the signal generator and 12v suppy have to be common? If so, why? |
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| RMCybernetics | Tuesday, 16th October 2007 8:44pm - No.1966 |
| Yes, because the current from the output of the signal generator will only flow if it has a path to the ground of its own power supply. |
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| Kevin A | Wednesday, 17th October 2007 7:10pm - No.1970 |
| Even if it's being powered by a separate 9v battery? |
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| RMCybernetics | Thursday, 18th October 2007 1:35am - No.1973 |
| Yes. The current flows out of the +9V battery through the signal wire, then through the drive transistors. There needs to be another wire returning to the other connector of the 9V battery to complete the circuit. |
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| Echbert | Thursday, 18th October 2007 10:42am - No.1974 |
| My circiut was working perfectly for some time,but all of a sudden it lost a lot of power,The output voltage became very poorand the 2n3055 transistor becomes very hot as soon as i apply power to the circuit.Can a blown capacitor on the rotary switch be the cause? |
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| RMCybernetics | Thursday, 18th October 2007 11:16am - No.1975 |
| Sounds like a damaged 2n3055 to me. If you are making sparks, the ignition coil will make a huge amount of back EMF whenever a spark stops. If you have nothing (like a snubber or MOV) to limit the voltage of these EMF spikes, they will damage your drive circuit. |
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| Dave | Friday, 19th October 2007 8:46am - No.1982 |
Thanks for the helpful info. I've got two questions, though:
1) Would it make sense to optically isolate the signal generator section from the power stage (e.g. use the phototransistor of an optoisolator as the first stage of the Darlington pair)? Then if back EMF roasts the optoisolator, it wouldn't affect the comparator and 555.
2) Where would be the best place for a varistor in this circuit? Would it be across the primary terminals of the coil, or between the collector and emitter of the power transistor? I'm thinking the latter option makes more sense, since it would shunt any high-voltage EMF to ground and (hopefully) bypass the power transistor (sparing it from an untimely demise ;^) ).
Thanks in advance,
Dave |
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| john | Friday, 19th October 2007 2:47pm - No.1983 |
| i built your crcuit but instead of the byf51 npn transistor i used the basic square wave circuit but after 5 minytes of 7.2 volts the timer blew and i had 6amp 1000v diodes in each direction of the out signal wires it only worked for so long can you suggest why im having these problems thankyou |
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| Awsome High Voltage | Friday, 19th October 2007 9:48pm - No.1985 |
instead of using the signal gen. i used my
ipod playing a constant tone.
it works great! |
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| RMCybernetics | Saturday, 20th October 2007 12:49am - No.1990 |
Dave,
1) Yes that is a good way to protect your circuit.
2) There are many ways to do this. You could place a mov across your load but this would add capacitance (decreasing dI/dt) and would need to be rated to dissipate a reasonable amount of power. Placing one between c and e of the transistor would also work if it were rated for similar power levels.
You can also place a MOV or zener diode between base and collector so that the transistor automatically switches on if the voltage is high.
john,
Yes, read the information on this page. |
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| john | Sunday, 21st October 2007 2:01am - No.1999 |
yer i read it but dosent state how to protect my ic chip i iwll try thr indicator using the 1kr and the light bulb thats a good idea yes but still does not protect my ic also would a mosfet be more effective in this circuit i herd that the 2n3055 acts like a resistor when in circuits like this?
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| RMCybernetics | Sunday, 21st October 2007 2:14am - No.2001 |
| Many other transistors can be used. This circuit uses a mosfet. |
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| justin | Monday, 22nd October 2007 12:47pm - No.2016 |
| hey its me again havent been here for a while but i have a problem lol im trying to run my tesla through an ignition coil but nasty feedback screws my 555 so i thought of this simple circuit wheather it works or not i dont know but i wanted you to cheack over it if thats ok by you otherwise never mind. |
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| RMCybernetics | Monday, 22nd October 2007 10:04pm - No.2017 |
| Just added a bit more info to the article about protecting circuits. |
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| Albert Como | Tuesday, 23rd October 2007 2:31am - No.2020 |
| I'm using a square wave generator. Could I use an SCR instead of the power transistor? |
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| justin | Tuesday, 23rd October 2007 8:30am - No.2021 |
my picture did not send urrr ohh well its pretty similar to yours only i have two caps in parrallel and two sets of 1k plus lights in parrallel and two 6amp diodes in the same direction in serires plus transistor protection lol i really dont want to blow my circuits , my caps are rated at 0.1uf 3000 volt tolerance, aside from all this i have a problem with my magneto coil , its not made for high frequencies and so as a result discharges between the hv out and primary i was thinking of pouring wax around the transformer to prevent this discharge would this work?
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| justin | Tuesday, 23rd October 2007 9:09am - No.2022 |
dear rmc i found a metal oxide varistor but i have no idea if it will work on my 12v circuit so if i specifi it can you tell me if it will work or not?
maximum operating voltage 275v AC
pulse energy rating 20 joules
peak pulse current 2000amps
device types ve17mo275k, 275A20A, TNR15G431K,INR1D431,TVR14431
$ 1.50 i dont know if this would work or not but a varisitor seems more efficiant for this circuit. |
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| RMCybernetics | Tuesday, 23rd October 2007 10:28am - No.2023 |
Albert Como,
No.
justin,
Wax will help prevent unwanted arcing but don't forget that wax is a hydrocarbon (a fuel) and will burn when soaked into things.
No your varistor will not be adequate. It will only activate at around 275 volts. If you are using a 2n3055, then the max voltage it will take (Vce) is 100V. You need a varistor that will activate just before 100V, or a transistor with a higher Vce (Vds for a MOSFET). |
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| Echbert | Tuesday, 23rd October 2007 8:44pm - No.2028 |
Should the mov be placed over the + and - points of the coil?If not where should it be placed?
Thanks a lot! |
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| RMCybernetics | Wednesday, 24th October 2007 11:23am - No.2030 |
| If you want to snub out the spikes at the source then yes, but this can effect performance. The basic idea is that you place a MOV between any two points to limit the voltage that appears there. For example; If your transistor has a max Vce of 100V, you could place a MOV rated for 90V between c and e (collector and emitter). |
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| Bob Dole | Thursday, 25th October 2007 10:24pm - No.2053 |
 Hello again! Yesterday I finally managed to get your driver [the top one] up and running. I was toying around with it, and a large arc jumped between the HV output and the negative terminal of the coil. Since then it has stopped working. I am using my own 555 timer astable circuit to create the square wave. I tested that part of the crcuit by using an LED indicator light and it seems to be functioning fine. So far, I have replaced the 3904 transistor [which I am using as my small signal transistor], all of the resistors and capacitors, and the ignition coil itself. I only have one 2n3055, so I haven't been able to replace it yet, but I did test it using a simple test circuit [see picture], and it seems to be functioning fine. I am at a loss. Do you have any idea what could be wrong? Any help is appreciated. |
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| jason t-bert | Saturday, 27th October 2007 7:19am - No.2058 |
| if you dont draw long arcs with you flyback will this help protect your circuit for exsample if i had this driver running my flyback charging a main cap will this reduce violence in my 2n3055? |
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| RMCybernetics | Saturday, 27th October 2007 12:27pm - No.2060 |
Bob Dole,
I would guess the 555 is blown. Are you able to verify that it is oscillating?
jason t-bert,
Yes, if the output of your coil is connected to a load there will be much less back EMF produced. |
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These
circuits will work great for driving ignition coils for high voltage but
they can be susceptible to damage from inductive spikes. When an ignition
coil is being driven unloaded (open circuit on the output) there will
be significantly increaded back emf and risk of damaging the driver circuit.
We sell an ignition
coil driver module which has built in protection against most spikes
that would damage a driver. It also includes an early warning indicator
which will show you how severe the back emf is from your load.
If
you build an ignition coil driver to make high voltage sparks and arcs,
you will need some sort of EMI protection for your circuit. Without it,
it is very likley you will destroy the transistors or driver ICs.
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