I have an NPN transistor that's connected over a 12V adapter. I have tried using a potentiometer to change the resistance of the incomming current. Even if i take the resistance down to 0, I end up with at most 11 Volts when measuring over the magnet.

I have measure the energy without the transistor, in that case it's 12V. Is this expected behaviour of a transistor or is something wrong?

  • 3
    I'm voting to close this question as off-topic because it has nothing to do with Arduino and should be posted on EE.SE. There isn't even the word "Arduino" once in the question.
    – Dat Ha
    Nov 15, 2016 at 16:05

1 Answer 1


Yes, it is, as both VCE(sat) and the "Collector-Emitter Saturation Voltage vs Collector Current" chart in the datasheet tells you.

  • By context I'm assuming "yes it is expected behaviou"
    – Himmators
    Nov 15, 2016 at 17:25
  • 1V seems a bit high. But since we don't know the current through the electromagnet, or the transistor, or the base-resistor, it might well be true.
    – Gerben
    Nov 15, 2016 at 19:36
  • @Himmators the actual vales in datasheet depend on your specific transistor -which you didnt state in this question Nov 15, 2016 at 20:38

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