Anjali... the most obvious problem I could see was that your Non-Inverting input does not have any path to ground. I ran your circuit in Multisim as follows
Sorry - it's a bit small. Now as you see I put in a 1K resistor to ground from the NI input. This should have the effect of reducing the gain by half so you should get a 2.5V output, however it is 2.74 V as you see.I also tried removing R4 and I got an output of 5.225V. So this is what you should have got.I am at a loss to find where the discrepancies come in...I have a theory but need more time to work through it. I think it is because this is a Non-Inverting configuration (in fact effectively it is a differential amp) so the gain equations are not quite the same as the inverting configuration.I'll try and come back to this a bit later, but meantime you should be able to get these results, I suspect you have a wiring fault or bad component somewhere if you do not get these.
Anjali apologies - your configuration should work (but then it did - kind of - with the Multisim simulation).I found an excellent article on it here;https://masteringelectronicsdesign.com/the-transfer-function-of-the-summing-amplifier-with-n-input-signals/
As you can see the maths gets quite involved. Much easier to use the usual inverting summing amp configuration
David, remove R4 from your Multisim simulation, and you will have Anjali's circuit. My hand-calculations of Anjali's circuit give Anjali's 5.0v output.
Anjali - glad you are getting somewhere. As an aside, I did the calculations for the non-inverting 2-input summing amp as shown here and you should get exactly 5V out.Where my 5.225V in Multisim came from, heaven knows. But the late great Bob Pease had a healthy distrust of circuit simulations. He once said "My favorite programming language is ... solder." It's hard to argue with that when you get crooked results like I obtained,
A non-inverting summing amplifier circuit designed to output 5 V was instead producing only 230 mV. Investigation revealed that the non-inverting input lacked a proper path to ground, which affected the output voltage. Simulation in Multisim showed that adding a resistor from the non-inverting input to ground improved the output voltage but altered the gain. Removing a feedback resistor (R4) restored the expected 5 V output in simulation. Theoretical analysis confirmed the circuit should yield 5 V output, but practical issues such as offset voltage and wiring faults can cause discrepancies. The complexity of the non-inverting summing amplifier's transfer function was noted, with a recommendation to use the inverting summing amplifier configuration for simplicity. Ultimately, correct wiring resolved the issue, aligning real-world results with theoretical expectations. Summary generated by the language model.
