Checking Steps:
- Make an assumption first, to make the checking steps easier, for example NPN or PNP.
- Determining the Base leg
- The black jumper on the ohm meter is the Base if it is an NPN type, so connect it to one of the transistor legs, then the red jumper is connected to the transistor leg other than the base, alternately, then if the needle moves the Base is correct.
- The red jumper on the ohm meter is the base if it is a PNP type, it is connected to one of the transistor legs, then the black jumper is connected to the transistor legs other than the base alternately, so if the needle moves the Base is correct.
- Determining the Collector
- One of the two unknown legs is C, the leg that is considered C is connected to the black jumper if we also consider it as NPN, while the other unknown leg is considered the Emitter and is connected to the red jumper, then the Base leg is triggered (by touching it with a finger), if the needle moves then the Collector leg is correct.
- One of the two unknown legs is the Collector, the leg that is considered C is connected to the red jumper if we consider it PNP, then the other unknown leg is considered the Emitter connected to the black jumper and the base leg is triggered (touched with a finger) if the needle moves then the Collector leg is correct.
- Determining the Emitter
- Once the Base and Collector are known, it is certain that the last remaining leg is the Emitter.
- NB: Basically, a transistor is a combination of 2 diodes and is a semiconductor component that acts as an amplifier and switch.
Simple Ways to Test Transistors
The Base characteristic is the relationship between IB and VBC, of course there are several diode curves because the Base-Emitter Junction material is known, it is a Diode if the ohm point is applied to the Base loop.
Formula:
IB = (VBB - VBC) - RBAnd the current will flow if the voltage between Base-Emitter > VBE, so that IB actively flows at a certain VBE value, while the value of VBE is usually listed in the datasheet, but for simplification it is generally known that VBE is 0.7 volts (silicon) and 0.3 volts (germanium).
Formula:
IB = (VBB - VBE) - RBTransistor As A Switch
It is a transistor that functions as a switch, where the transistor will be ON, if the transistor is biased Base, thus changing the condition of the Collector with the Emitter to appear as if it is short-circuited and the transistor will be OFF, if it does not receive Base bias, so that the Collector with the Emitter appears to be broken.
Illustration of Transistor as a Switch