Op Amp Circuit - Summing Amplifier - Are these Equations correct?

Thread Starter

matthej

Joined Oct 10, 2020
52
Hi,

I am trying to figure out the equations for the following circuit. First of all U1a is attached to a thermistor, so it looks like the Gain of the circuit will be proportional to the value of the thermistor (Vout/Vin = -Rf/Ri).

After that, for U1B, I am trying to figure out what is going on. It looks like its a summing amplifier?
So: Vout = (-Rf/Rin1)V1 + (-Rf/Rin2)V2 etc?

So would it be:

Vout = -(10K/R9+R10)(-5V) + -(10K/R4+R6+R7+R8)(-5V) + -(10K/R4+R6+R12+R13)(DAC value) + -(10K/R4)(U1A value)?

Does this look correct?

Thanks!opampcircuit_large.jpg
 
Top