[SOLVED] Transistor doesn't reach CUTOFF region.

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Mo_Sh

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Hi,

I am doing a simple circuit, a PN2222A transistor is switched on by a 5v and a 11v on the collector.
The problem is that when I ground the base I don't get 11 volts on Vout instead I get 7.5 volts.
Why this is happening?!
The circuit is as follows (I am connecting the base to the ground as this is the case that has the problem)
 

It should be 11V because the transistor shouldn't be conducting. Either the transistor is bad, you have it wired incorrectly or your voltmeter is drawing a lot of current!
7.5V is a likely value you might see if two of the transistor pins are crossed over, it is the kind of voltage you expect from a PN junction in it's breakdown region.

Brian.
 
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    Mo_Sh

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I guess you have connected it incorrectly. 7.5V would be a typical reverse Vbe breakdown. Check your connections

Keith.
 
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May be source direction changed ?? or change in transistor connection....
 
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    Mo_Sh

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Yup it's inverted, I inverted the transistor and it works okay now, however this connection is the opposite to what is mentioned by the datasheet .... weird.
Thanks all.
 

Be careful - some pictures of transistors show the view from the bottom, some the view from the top.

Keith
 
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