If a good transistor is connected, it will produce a short across the LED pair when the voltage is in one direction and only one LED will flash. ***If the transistor is open, both LED's will flash and if the transistor is shorted, neither LED will flash.

Components REQD.:


1) 555 Timer

2) Breadboard & Wires

3) 33k Resistor [x1]

4) 220R Resistor [x4]

5) 10uF Capacitor [x1]

6) 1N4148 Diode [x2]

7) LED [x2]

8) Transistor [any type]

9) 9V Battery

10) Switch ON/OFF [optional]