transistor polarity

Z

zkatz100

New Member

• Aug 19, 2010

• #1

if a negative voltage is applied to the collector of a transistor, and positive voltage is applied to the base, what will happen?

 

MikeMl

Well-Known Member

Most Helpful Member

• Aug 19, 2010

• #2

Depends on if it is an PNP or NPN. Also depends on where the emitter is connected. Also depends on the magnitude of the voltages.

 

Z

zkatz100

New Member

• Aug 20, 2010

• #3

the transistor is pnp. the emitter is connected through a relay coil to a neutral ground. the positive voltage is 5 volt. the negative voltage will ether be 12 or 5.

 

MikeMl

Well-Known Member

Most Helpful Member

• Aug 20, 2010

• #4

zkatz100 said:

the transistor is pnp. the emitter is connected through a relay coil to a neutral ground. the positive voltage is 5 volt. the negative voltage will ether be 12 or 5.

Click to expand...

Your connection seems strange to me. Here is what will happen. Your method works like an emitter-follower, with no gain. I think you want the second circuit, which switches with some gain...

 

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• DF62.png

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Z

zkatz100

New Member

• Aug 20, 2010

• #5

sorry, i messed up, it is npn.

 

MikeMl

Well-Known Member

Most Helpful Member

• Aug 20, 2010

• #6

Here are the two NPN configurations that make some sense...

 

Attachments

• DF62a.png

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