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Topic: Transistor/MOSFET not Working (Read 706 times) previous topic - next topic

DibDibs

OK, I've got that circuit setup and the lights are turning off fine if I ground the gate pin of the IRF540, but the 2N2222 doesn't appear to be working, when I give the base of the 2N2222A 5V, the lights do not turn off, they remain on.

What could be the problem here?
Sorry about my naïvety, I haven't had much experience with MOSFETS and transistors.

MarkT

If you give the base of the 2n2222 5V it will fry immediately.  The base resistor is essential to
the circuit.
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tinman13kup

OK, I've got that circuit setup and the lights are turning off fine if I ground the gate pin of the IRF540, but the 2N2222 doesn't appear to be working, when I give the base of the 2N2222A 5V, the lights do not turn off, they remain on.
Perhaps you should post EXACTLY how this is wired up. The IRF540 is an N-ch mosfet. You do not ground the gate to turn them on. A ground on the gate is to turn it OFF
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

MarkT

Perhaps you should post EXACTLY how this is wired up. The IRF540 is an N-ch mosfet. You do not ground the gate to turn them on. A ground on the gate is to turn it OFF
reread the post: ''the lights are turning off fine if I ground the gate''

But yes I'm worried the NPN's base was shorted to 5V rail and destroyed.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

dlloyd

I think he meant "base resistor" (if he followed the diagram). Here's how to identify the pins of the transistor:


tinman13kup

reread the post: ''the lights are turning off fine if I ground the gate''

But yes I'm worried the NPN's base was shorted to 5V rail and destroyed.
My mistake. I got in a hurry in anticipation of going out and shoveling snow...Yeah, yippie....can't wait to do it again....

He could try to meter out the transistor, or just try a different one if he has one available.
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

tinman13kup

Still, a post with exactly how it is wired up would be beneficial. A picture too, to make sure pins were not mistaken.
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

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