Transistors

First thing i learned with transistors if how to determine an NPN type or a PNP type by use of a Multimeter. By using the diode function on the multimeter, i found it simple enough to find this, as a transistor is basically two diodes back to back. The first transistor i tried was an NPN type, i found this out by putting the probes of the multimeter on the three pinouts on the transistor. After finding the collector, base, and emitter pin, a then put the positive probe on the base and the negative lead on the emitter. The multimeter showed continuity. By trying the same thing with opposite leads, the meter showed an open circuit. Trying this same test with a PNP type transistor, i had the opposite results.

I continued to use the Diode test mode to test voltage drops across the transistor. On a NPN type, Vbe(Voltage from Base to Emitter) showed .726v, Veb(Voltage from Emitter to Base) showed an open circuit, Vbc(Voltage from Base to Collector) showed .721v, Vcb(Voltage from Collector to Base) showed an open circuit, Vce(Voltage from Collector to Emitter) showed an open ciruit, and Vec(Voltage from Emitter to Collector) showed an open circuit also. On the PNP type, Vbe showed an open circuit, Veb showed .725v, Vbc showed an open circuit, Vcb showed ,721v, Vce showed an open circuit, and Vec showed the same. By doing these tests, and seeing that reversing the polarity of the tester showed open ciruits, i could see the diode-like characteristics of the transistors. The tested also showed that the device needed switching before there would be any continuity through the Vce or Vec circuit.