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use pnp transistor as switch

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mshh

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i have -0.5 volt (negative) and i want to use it to turn on pnp transistor and turn it off when the signal is 0.5 volt(positive) ?
 

KlausST

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Hi,

give +0.5V to the emitter of the BJT.
And use a current liitng resistor at the base (10k?)

Klaus
 

crutschow

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0.5V is not enough to forward bias the base-emitter junction and turn on the transistor.
What are you trying to switch with the transistor?
What exactly are you trying to do?
 

mshh

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I want to convert the -0.5 volt to 20 volt. I thought that the transistor could be used to capture 20 volt if i supplied it with the same value.

- - - Updated - - -

Hi,

give +0.5V to the emitter of the BJT.
And use a current liitng resistor at the base (10k?)

Klaus

I want to take output 20 volts or at least +0.5 volt
 

KlausST

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Hi,

... before you wanted to switch ON a PNP..
... now you want to convert -0.5V to 20V

... without talking about current. Why a PNP?

Why not use a comparator? What about power supplies? What about other devices?

Maybe you should say what you really want...and give more informations...

Klaus
 

crutschow

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Show us a diagram of exactly what you are trying to do.
You explanation is not clear.
 

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