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I'm having a problem running fairly easy transistor case. I'd like to feed 12V to a short (9 diodes) LED strip using a signal from 3.3v controller. However after reading multiple articles on transistors, I can't wire this up correctly.
In this curcuit I'm using 2N3904 NPN transistor.
So I placed R1 so that there's 1mA current going to collector's base pin.
Collector is wirred directly to 12V and collector has:
- R2 as a pulldown resistor, so that it's grounded
- a short SMD5050 white strip (so that it doesn't exceed 200mA)
My intention here is to simply control 12v led stripe with a low voltage microcontroller.
The problem with this design is that I have only 2.7V on emitter when the button (SW1) is pressed - which looks like as if the base was used as a collector but I have checked the wiring with transistor datasheet multiple times.
I think I'm missing something very obvious, any ideas?