I can't fathom why this (single supply inverting opamp) circuit not working?

Thread Starter


Joined May 24, 2024
I am learning about op amp for some days. I always struck when I try to simulate circuits. I can't fathom why the single supply inverting Opamp not working.
I have included the **PROTEUS** simulation file with this.
I have run other files, I downloaded from internet, They are working just fine. but whenever I try to cook the circuit I always stuck. I can be sure that its not software fault.

If any one can help me that would be appreciated. thanks in advance:)



Joined Jan 30, 2016
Welcome to AAC!

Unfortunately many don't have access to Proteus. Can you post a schematic of your circuit and say what isn't working for you.


Joined Mar 14, 2008
You need to fathom the availably supply voltage.
As BTPH noted, the usual problem is that a single supply, inverting op amp cannot give a negative output with a positive input.
An op amp doesn't generate voltage, it just controls the available voltage from the supply.

It will work with a negative input which gives a positive output (assuming it's a single-supply type op amp).
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Joined Jan 23, 2018
Posts #3 and #4 are right. THAT is why for many single supply circuits the non-inverting input is biased to half the supply voltage. It works well BUT the output to a speaker load must be AC coupled. Usually that means a big capacitor in series with the output. Andthe big capacitor takes up space and may not be cheap. and if it is supposd to be DC coupled things get complicated.