Two stage op-amp not working.

Thread Starter

guru@123

Joined Oct 23, 2020
10
Hello, I wanted to build a two stage amplifier, but in my case only first stage is amplifying the signal whereas the second stage is just acting as a buffer and not amplifying the output obtained from first stage. The input to first stage is 20mV and its output is -1.92V and the same thing is fed to second stage but giving output that is -1.92v. I have attached my circuit below. Kindly help.TINA CKT.JPG
 

ericgibbs

Joined Jan 29, 2010
12,884
hi 123,
Inputting -1.92v to the 2nd stage , which has a gain of 100, what are you expecting from the 2nd output.
It must be hard into saturation.
E
 

Alec_t

Joined Sep 17, 2013
12,060
Guru, the feedback of the second stage is incorrectly configured. The R4/5 tap should connect to the inverting input, as Eric shows..
 

ericgibbs

Joined Jan 29, 2010
12,884
hi sg,
The LTSpice models for the 741 are not ideal, so the Vout's will be suspect.
E

4558 data, with +/-V 15v supplies, Vout limits early. [ the TS has only +/-10V]

AAA 1185 18.44.gif
 
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