With this circuit we can check the status of silicon or germanium diodes of general use or rectifiers. The circuit verifies the conduction of the junction, causing the indication to be given by the LED lighting.
If the diode is good, only one of the LEDs lights up. If the diode is shorted, the two LEDs light up and if it is open, none of the LEDs light. If one of the LEDs comes on strongly and the other is too weak, then we have a leaky diode.
The circuit makes use of a small transformer of 6 to 12 V of secondary with current of 100 to 300 mA. The resistor R1 can be increased to 1 k if a transformer with more than 6 V is used. In figure 1 we have the diagram and the jumper of terminals.
The diode under test is clawed for ease of handling. The circuit can be installed in a small plastic box.
Material list
LED1, LED2 - Common red LEDs
T1- 6 to 12 V transformer with 100 to 500 mA current. Primary according to the local power grid.
R1 - 470 ohm x 1/8 W- resistor - yellow, violet, brown
Miscellaneous:
Power cable, terminal bridge, wires, solder, alligator clips, etc.
