We used the two LED flasher with transistors only. Today we come to experiment the 3 LED flasher circuit as Figure 1 that also use astable mutivibrator with 3 transistors to drive all LEDs.
The Flash rate of LED1-LED3 in each frequencies output are easily changed simply by changing one, or three of the timing capacitors (C1, C2, C3). Which each capacitor does not need same capacitances.
The Resistors-10K are used to bias transistor conducting.
Then, we insert VR1-10K-potentiometer to control base current of transistors, which importance they are used to simply adjusts the flash rate.
And, each the 470 ohms resistors is used to control current flow through or limits current to each LED.
We assemble all components into the breadboard as the video below.
You will see that, the LEDs alternately flash ON and OFF about once per second, always two LED will glow each time.
The components List
Q1-Q3: CS9013, 500mA 30V NPN transistors
C1-C3: 47uF 35V Electrolyte capacitors
VR1: 10K (B) Potentiometer single
R4-R6: 470 ohms, 0.25W resistors
R1-R3: 10K, 0.25W Resistors
LED1-LED3: LED as you want
PCB or breadboard.
Read more LED flasher circuits
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