Semiconductor Tester

I built this in shop in Junior High School.

 

Operation:

Put the transistor or SCR in the socket.

Push S2. Note the lights.

Switch S1.

Push S2. Note the lights.

 

If only the NPN light lit for the whole procedure, you had a good NPN transistor. Same for PNP.

 

If both lights lit, you had a short.

 

If no lights lit, you had an open.

 

 

Done