RC-circuit - a way to create a temporary delay in your circuit by connecting a resistor and a capacitor. It's super easy. And it is very useful.
«R» - is a resistor, and «C» - this capacitor. That's where the name «RC». And that's how you connect these two elements:
How does the RC-circuit?
Condenser - an element which operates on the principle of a small battery. You can charge it with voltage. And you can use this power for a short time until the capacitor is discharged.
The time required to increase the voltage on the capacitor, it is our time delay.
A capacitor with a higher value Farad can store more energy than a capacitor with a smaller value. Consequently, also it requires more time to charge the capacitor of high capacitance compared with a capacitor of small capacity.
"The rate of charge" is defined by how much current flows through the condenser.
The higher the current, the faster it is charging.
If we connect the capacitor directly to the battery, there is no limit on the amount of current flowing through the capacitor (except for the maximum capacity of the battery).
Flowing much current, the capacitor is charged very quickly, and the delay becomes very small.
That's where, in fact, a resistor, and comes into operation.
RC time constant
You can calculate your RC delay time of the delay element by a simple formula:
τ = R * C
resistor The aim is to reduce the current flow to the condenser, to slow down the time required for charging.
This RC time constant, also called tau, which is written as τ.
This gives you the time required to raise the voltage from zero to about 63.2% of the applied voltage.
If your RC delay element has 10 kOhm resistor and a capacitor 100 uF, your delay becomes:
τ = 10000 Ohm * 0,0001 F
Multiply these two numbers, and you get a 1 second delay.