Is there situation, where a transistor is used with base open and using only emitter and collector ?

If yes, why such a configuration might be used.

2 Answers

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  • Anonymous
    10 years ago
    Favorite Answer

    I think the 'bog standard' answer your looking for is No. However.......

    There used to be, in the old days, transistors called OC71's (germanium types) that had the transistor junctions encapsulated within small glass envelope which was then covered in black paint and which had a red dot to mark the collector. It was possible to scratch off the paint and expose the junctions. You could then use light to alter the conduction properties between the emitter and collector and operate a circuit.

    Additional:

    You will find that optoelectronic devices use a similar principle. In these devices infra red light from a light emitting diode (LED) shines onto the exposed base of a transistor in order to alter the conduction between the emitter and collector. Both the LED and transistor are encapsulated within the same package and are used when you wish to provide electrical isolation or a change in voltage levels when transformers are inappropriate. You will find these devices in most switch mode power supplies (SMPS) that need to switch the small ferrite transformer at 40KHz using a MOSFET.

  • 10 years ago

    That would be a rather useless configuration for a transistor. You might as well just leave an air gap between the emitter and collector, because that is how such a circuit would behave.

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