I am new to this, but have been doing a lot of reading to get up to speed,
The circuit I am designing has two primary inputs which go into negative input of difference op amps, with a set reference on the positive input, so the input can be inverted from a rising voltage to a falling voltage.
The outputs need to be summed and I was just going to simply put them through a passive averager setup, basically connecting each output to opposite ends of a 100K pot and using the wiper as the output of the averaged sum, this would also allow me to vary the mix between the two outputs to be 50:50, 90:10, 30:70, etc.
I thought this was a pretty elegant solution, then thought, as the difference amps have negative feedback, would the averaged voltage influence the feedback amount and hence alter the output?
Do I need to put the outputs through a buffer amp before summing/averaging or can it be done by using additional resistors on the output of each, say 500K - 1M?
Thanks in advance.
Edit: Just thought I better add, it is not an audio circuit, so a bit of "noise" is not an issue, the final voltage output goes to a pwm generator to drive a solenoid, the pwm unit is off the shelf type, controlled by a small pot, that is where I was going to connect in, I suspect internally it first goes through an amplifier as well before generating the square wave pulse, so I expect the op amp outputs to be adequate.
The circuit I am designing has two primary inputs which go into negative input of difference op amps, with a set reference on the positive input, so the input can be inverted from a rising voltage to a falling voltage.
The outputs need to be summed and I was just going to simply put them through a passive averager setup, basically connecting each output to opposite ends of a 100K pot and using the wiper as the output of the averaged sum, this would also allow me to vary the mix between the two outputs to be 50:50, 90:10, 30:70, etc.
I thought this was a pretty elegant solution, then thought, as the difference amps have negative feedback, would the averaged voltage influence the feedback amount and hence alter the output?
Do I need to put the outputs through a buffer amp before summing/averaging or can it be done by using additional resistors on the output of each, say 500K - 1M?
Thanks in advance.
Edit: Just thought I better add, it is not an audio circuit, so a bit of "noise" is not an issue, the final voltage output goes to a pwm generator to drive a solenoid, the pwm unit is off the shelf type, controlled by a small pot, that is where I was going to connect in, I suspect internally it first goes through an amplifier as well before generating the square wave pulse, so I expect the op amp outputs to be adequate.
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