How to identify terminals of a transistor?
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Depending on which of the three terminals is used as common terminal, there can be three possible configurations for the two-port network formed by a transistor: Common emitter (CE), Common base (CB), Common collector (CC).
Connect the terminal marked positive, first to the collector and measure the resistance. Then take it to the emitter. In both cases the meter should deflect (indicate open circuit for a PNP transistor). It is next necessary to connect the meter negative or common to the collector and meter positive to the emitter.
Transistors may be NPN or PNP which are available in Plastic casing or Metal Can package. In plastic casing, one side of the transistor is Flat which is the front side and the pins are arranged serially. To identify the pins, keep the front flat side facing you and count the pins as one, two etc. In most NPN transistors it will be 1 (Collector), 2 (Base) and 3 ( Emitter ). Thus CBE. But in PNP transistors, the condition will be just reversed. That is EBC. In Metal can types, the pins are arranged circularly. Just see a Tab in the rim. In NPN type, the pin close to the Tab is Emitter, the opposite one ,the Collector and the middle one, base. In PNP type the pins are reversed. Pin close to the Tab is Collector.
But this is not a standard pin configuration. The pin arrangement may vary in some transistors. So to get an idea, the following table will help you.
2. Field Effect Transistor(FET)
To identify a Field Effect Transistor, one should keep the curved portion facing him/her and start counting in anti clockwise direction. The 1st one is the source, then the gate and then the drain.
3. MOSFET – Metal Oxide Semiconductor Field Effect Transistor
Usually in some cases the pins of MOSFET are accordingly labeled as G, S and D denoting Gate, Source and Drain. In some cases, it is recommended to consult the datasheet of the MOSFET. Normally making the flat side faced towards you, the pins are labeled as S, G, D starting from left to right.
4. IGBT- Insulated Gate Bipolar Transistor
For few practical IGBTs like GN2470, the raised up surface is placed towards the person holding it such that the shorter one in the middle is the cathode. The one in the left is the Gate and the one in the right is the Emitter.
5. Phototransistor
For practical phototransistors like L14G2, keeping the curved surface towards the person holding it and starting from the clockwise direction, the 1st one is the collector, the second one is the emitter and the third one is the base.
This table shows the pin connections of Regulator IC, MOSFETs, Temperature Sensors, Melody IC, Phototransistor etc
Connect the terminal marked positive, first to the collector and measure the resistance. Then take it to the emitter. In both cases the meter should deflect (indicate open circuit for a PNP transistor). It is next necessary to connect the meter negative or common to the collector and meter positive to the emitter.
Transistors may be NPN or PNP which are available in Plastic casing or Metal Can package. In plastic casing, one side of the transistor is Flat which is the front side and the pins are arranged serially. To identify the pins, keep the front flat side facing you and count the pins as one, two etc. In most NPN transistors it will be 1 (Collector), 2 (Base) and 3 ( Emitter ). Thus CBE. But in PNP transistors, the condition will be just reversed. That is EBC. In Metal can types, the pins are arranged circularly. Just see a Tab in the rim. In NPN type, the pin close to the Tab is Emitter, the opposite one ,the Collector and the middle one, base. In PNP type the pins are reversed. Pin close to the Tab is Collector.
But this is not a standard pin configuration. The pin arrangement may vary in some transistors. So to get an idea, the following table will help you.
2. Field Effect Transistor(FET)
To identify a Field Effect Transistor, one should keep the curved portion facing him/her and start counting in anti clockwise direction. The 1st one is the source, then the gate and then the drain.
3. MOSFET – Metal Oxide Semiconductor Field Effect Transistor
Usually in some cases the pins of MOSFET are accordingly labeled as G, S and D denoting Gate, Source and Drain. In some cases, it is recommended to consult the datasheet of the MOSFET. Normally making the flat side faced towards you, the pins are labeled as S, G, D starting from left to right.
4. IGBT- Insulated Gate Bipolar Transistor
For few practical IGBTs like GN2470, the raised up surface is placed towards the person holding it such that the shorter one in the middle is the cathode. The one in the left is the Gate and the one in the right is the Emitter.
5. Phototransistor
For practical phototransistors like L14G2, keeping the curved surface towards the person holding it and starting from the clockwise direction, the 1st one is the collector, the second one is the emitter and the third one is the base.
This table shows the pin connections of Regulator IC, MOSFETs, Temperature Sensors, Melody IC, Phototransistor etc
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