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Making Electronic CircuitsThis page should help you learn about how different components can be combined to create useful circuits. We've included a range of example circuit diagrams and explanations of how they work. The circuits start from the very basics and move on to more advanced practical circuits. Connecting Resistors TogetherResistors are commonly used for limiting the current available to part of a circuit, but they are also used together in networks to allow voltages to be distributed how you want it around a circuit.
This is commonly written as RT = R1 + R2 + R4 ......
When connecting resistors in parallel of different values the following formula is used. 1/RT = 1/R1 + 1/R2 + 1/R3
Useful Link: Voltage Dividers This diagram shows a simple example using a single battery and two resistors. The three points (A,B,C) on the circuit are where the voltage measurements can be made. If this battery is 10V then the voltage between 'C' and 'A' will also be 10V. The voltage at 'B' is determined by the ratio of the values of the resistors R1 and R2. For example; if R1 and R2 are of the same value then the voltage at 'B' will be exactly half the voltage between 'A' and 'C'. The polarity of 'B' can be considered as either positive or negative depending upon whether you use 'A' or 'C' as reference for the measurement. From this simple example you can have a three rail power supply with outputs of either 10V, 5V, 0V, or 5V, 0V, -5V with respect to A,B,C. To get different voltage ratios you just alter the resistance ratio. For example; if R1 is 1k Ohms, and R2 is 9k Ohms, the voltage between 'C' and 'B' will be 1V, while the remaining 9V can be measured between 'B' and 'A'. Connecting Capacitors TogetherCapacitors are used as temporary energy storage devices and are often used for generating or tuning signals. Capacitors can also be connected up to work in the same way as as the voltage divider described above. The formulae used for capacitor networks are similar to those used for resistors but they are used in reverse with respect to series and parallel configurations.
1/CT = 1/C1 + 1/C2 + 1/C3 .......... When making a high voltage capacitor like an MMC, it is common to create several series strings of capacitors to match the desired voltage rating, and then to connect these in parallel.
CT = C1 + C2 + C4 ......
RC Circuits (Resistors & Capacitors)An RC circuit is simply some combination of a resistor and a capacitor. The value of the resistor in a circuit with a capacitor will change the rate at which the capacitor can be charged and discharged. This relationship is known as the RC time constant. The combination of resistors and capacitors can be very useful for timing circuits and also filtering signals.
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