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I am learning about NPN transistors and I could not find how to connect the transistor so it operates in the saturation region.The circuit that I have made works in the Active region,because when I run the simulation the current on the emitter is higher than the current on the base.

ROBOTICS
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  • Short out R2... –  Aug 05 '20 at 14:20
  • Increase R3 or decrease R2. – The Photon Aug 05 '20 at 14:20
  • I removed R2 and R3 and it works! – ROBOTICS Aug 05 '20 at 14:27
  • Thank you BrianDrummond and ThePhoton! – ROBOTICS Aug 05 '20 at 14:30
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    To saturate the transistor, you have to make its collector-emitter voltage Vce (almost) zero. For this purpose, its collector current has to be big enough so that the sum of voltage drops across R2 and R3 becomes (almost) equal to the voltage V2 of the power supply. – Circuit fantasist Aug 05 '20 at 14:33
  • BJT transistors are 'current controlled' devices. Whether or not the BJT is in saturation is dependent on the amount of current flowing into the base relative to the amount current flowing into the collector. That's a common sticky point when learning because we're used to thinking in terms of voltages being the controlling element. R2 is messing you up because the IR drop through it creates a voltage (V=IR, right?) and that voltage is raising the emitter and thus also the base to a high enough voltage that the base driver can't provide adequate current. – Kyle B Aug 05 '20 at 16:34
  • Still, do you have any idea how this circuit works? – Circuit fantasist Aug 05 '20 at 16:46
  • I understand it now, I did more research and found a video ,that explained it – ROBOTICS Aug 06 '20 at 13:15

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