How to Stabilize the Output Voltage Using a OP AMP Comparator Circuit and Draw Current(1A) from it?


Joined Mar 14, 2008
OK. What is the purpose of the 741? How is it being used in this particular circuit?
Glad you asked. :)
Pin 2 is the 741 summing junction, with linear negative feedback from -Vo to this junction.
It adjusts -Vo so that the pin 2 voltage is equal to the pin 3 (+) voltage (0V / ground), which means -Vo always equals (+)Vo (the tracking function).

The 741 may be "comparing" two voltages, but it's doing it in a linear feedback mode, not as an open-loop, digital-out comparator.



Joined Mar 14, 2008
Exactly. So a comparator with an analog output?
No. Read what I said again.
The usual definition of an analog "comparator" circuit is a high gain amp with a differential input, operating open-loop (or possibly with a small positive feedback to give some hysteresis to the trip point) and giving a digital (2-state) output.
If the amp is operated with closed-loop negative feedback to give an analog output, it is operating as an op amp, not a comparator.

Comparators, by definition, do not have an analog output.


Joined Aug 21, 2008
Maybe this will help, referring to the schematic in post #22, the circuit with the opamp is applying feedback based on how close to ground (pin 1, - input) the inverting input (pint 2, - input) is. The amplified difference is used to force the negative output voltage to a voltage tcauses the voltage on pin 2 to be as close as possible as ground. Essentially, comparators only have two states. Opamps have continuously varying outputs.