This versatile circuit will help you test just about every electronic component. Note the names for the input slots. You must insert the device in the sockets and test them as follows.

Transistors- If you insert the transistor’s B-E junction (or a shorted transistor) to the C & E sockets a LED will light, but you will know that the transistor is placed in the wrong position because the proper LED should light only when you press S1 (Push-button). You may want to use 5 sockets placed "C-E-B-C-E" to avoid bending the transistor leads. A bi-color LED may be used instead of two the polarity LEDs. With the transistor sockets you can also check SCRs, LEDs, etc.: -To check SCRs, place the polarity switch in the NPN position, insert the SCR matching A-C, K-E and G-B, press S1 and expect the "NPN" LED to light and stay on. -To check LEDs, place the polarity switch in the NPN position, insert the LED in the B (A) & E (K) sockets and press S1, the LED under test should light.

In addition, there are two more sockets (+ & -), which can be used to check diodes, continuity, capacitors, etc.:

-To check diodes, place the polarity switch in the NPN position, insert the diode matching A-(+), and K-(-), press S1, the "NPN" LED should light.

-To check continuity, place the polarity switch in any position, insert the leads to (+) and (-), press S1, a polarity LED should light.

-To check capacitors, insert the capacitor in the right polarity (+) & (-). Then rapidly change the polarity to PNP, then to NPN, then back to PNP… the LEDs should light alternatively. This test only checks charge & discharge, not capacitance value.

You can find many other uses to this amazingly cheap device. Have fun, just don’t apply voltage to the sockets!!!