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go/no go transistor

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New Member
i have been messing with electronics for a long time but i am now trying to figure out how it works and exactly what certain things do.
So im trying to put together this schem.
But i am a little confused.
I get confused at the bottom left where it says npn and pnp
and the wire coming off the 9v going know where.
im not sure how this gets wired in this area.
If someone can please explain or point me in the right direction i would appreciate it. Also i have searched these threads and Google for an answer but i could not find anything to help me so i figured i would post it here.
Thanks for any help



Well-Known Member
Most Helpful Member
The double-pole switch selects between testing a PNP or NPN. A 9V battery connects between +9V and the ground symbol. No on-off switch required if no transistor is left plugged in the socket. A shorted or leaky transistor would kill the battery even if the Test switch is open.

A good transistor lights a LED only if it has some current gain while the Test switch is pushed. Which LED lights is determined if an NPN or PNP transistor is being tested.

If the transistor is open, neither LED lights. If an LED is always lit, then the transistor is shorted. A refinement would be to use a Red/Green inverse-connected double LED (in one package) for the two shown in the schematic.
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New Member
Mike im not to familiar with symbols and circuits.
But you helped me out a lot.
Thanks for helping a stranger.
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