Introduction: Two Transistor LED Flasher Circuit
How to make a circuit to make two LEDs flash back and forth. This is also called a free running multivibrator.
Step 1: The Parts
For this project you'll need the following:
-PNP transistor x2 Q1, Q2
-4.7-22 uf capacitor x2 C1, C2
-470 ohm resistor x2 R1, R2
-100k ohm resistor x2 R3, R4
-5mm LED (any color) x2 LED1, LED2
-Solid core wire, 22 gauge
-4 AA holder x1
Step 2: Insert the Transistors
The transistors leads were to close together, so using needle nose pliers I bent them to fit in the breadboard. Insert the transistors two rows away from each other. Insert it so the rounded side is facing outwards and the side with the letters is facing towards the breadboard.
Step 3: Circuit Diagram
Step 4: Assemble the Circuit
Step 5: Troubleshooting
If the circuit fails to operate:
-Check if the transistor is in backwards
-Make sure that they are both PNP transistors
-Make sure that the LEDs and capacitors are not in backwards
-Be sure that none of the bare leads are coming in contact with one another
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