Page 22 - Electronics Starter Kit_EN

Wiring diagram

3.5 Circuit Explanation

We have two capacitors in this circuit so the circuit will charge and discharge them to make the
LEDs flashing, to understand how this circuit works let's suppose that C1 is already charged and
C2 is empty, C1 connected to the base of TR2, so this capacitor will make the transistor (TR2) in
the saturation mode and LED2 will light up, at the same time C2 will charge, it will get the
positive side through R1 and will get the negative side through TR2, until C2 gets fully charged
C1 will be empty, C2 connected to the base of TR1, so this capacitor will make the transistor
(TR1) in the saturation mode and LED1 will light up, at the same time C1 will charge, it will get
the positive side through R2 and will get the negative side through TR1, and so on.

Note:
If you want to change the time of flashing, there are two ways:
1. Changing R1 and R2 to a bigger value so the time of flashing will be longer, and vice versa.
2. Changing C1 and C2 to a bigger value so the time of flashing will be longer, and vice versa.
You can change them individually, for example you can change only R1 or C1 and you will get a
different time for each LED.

3.6 Example Picture

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