I've tried to make the following circuit (both physically and simulated):


simulate this circuit – Schematic created using CircuitLab

Not sure if its correct but below is the simulink model (same as physical one): Circuit modeled in simulink

There is one thing I can't understand, I tried measuring voltage across R1 and R2, I though it would be the same, but instead as shown in simulink, the R2 voltage shows ~4.8V and R1 shows ~4.3V (on physical model multimeter has shown 5V and ~4.3V

Why would voltage across R1 be less 5V (4.3V) as if I was measuring the voltage drop on base-emitter of Q1? On physical model the C4881 transistor was used. While on simulink some standard settings were there.


Your transistor is operating in saturation. Vbe is typically 0.6 or 0.7 volts, and Vce,sat is typically 200 mV.

So the the voltage across R1 is (5-Vbe) ~ 4.3 V.

The voltage across R2 is (5-Vcesat) ~ 4.8 V.


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