How do you figure 4.3V and 358mA?
Assumed the op amp is a rail to rail and the power is 5V, the (-) voltage less than (+) voltage of the op amp, and the bjt Vb>Ve=0.7V, Vb=5V, Ve=5V-0.7V=4.3V.How do you figure 4.3V and 358mA?
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Hi, why Vb=5V, did you assume this value or Vb is equal to (+) voltage of op amp?Assumed the op amp is a rail to rail and the power is 5V, the (-) voltage less than (+) voltage of the op amp, and the bjt Vb>Ve=0.7V, Vb=5V, Ve=5V-0.7V=4.3V.
Assumed the fet in the saturation status, I = 4.3V/12 Ω =358mA.
If the power of op amp is changed then all the voltage will be change.
So you are assuming the circuit is designed such that the op amp runs open loop and saturates?Assumed the op amp is a rail to rail and the power is 5V, the (-) voltage less than (+) voltage of the op amp, and the bjt Vb>Ve=0.7V, Vb=5V, Ve=5V-0.7V=4.3V.
Assumed the fet in the saturation status, I = 4.3V/12 Ω =358mA.
If the power of op amp is changed then all the voltage will be change.
If I understand you correctly, I think you are correct, as long as you include the resistor. The constant output voltage of the 1st amp less Vgs across the resistor will establish as stable a current in the left side of the mirror as the original circuit, I think.And I don't know why the op amp on the top is needed .I think the output voltage of the left side op amp can go directly to Base of BJT, and then Ve goes to FET
I assuming that if using a rail to rail op amp then it could be have that 5V output, when the power for op amp is 5V.Hi, why Vb=5V, did you assume this value or Vb is equal to (+) voltage of op amp?
Assuming that the op amp(rail to rail) is runs as a voltage comparator, and the power 5V for op amp, if using a real voltage comparator the output voltage could be difference, but the result and what I assuming is the same.So you are assuming the circuit is designed such that the op amp runs open loop and saturates?
I also a little confused and I was afraid of what I thought was wrong, so I did the test, but I just connected a 100 Ohms and 3V/20mA led to be the load, and the V+ of op amp I connected to 5V.I have to admit to being totally confused. What prevents the upper amplifier from equalizing its negative input to +5V when the supply is (say) +12V? I didn't build anything but it "works" just fine in simulation using an LM324 or LM358 single supply op amp. Isn't this simply a classical series pass regulator topology?
Admittedly, I just connected the +ve input to a single +5V source rather than the more complicated 5V op amp regulator.
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