This carries over from a previous thread I made.

I have an op amp circuit designed that works on my test bench, but not in my vehicle. Op amp reference voltage is set at 12Vdc and I have a square wave as Vin. See picture below.

It is thought that the reason for the circuit not working properly is because Vin has a floating ground which is causing the op amp trip levels to act differently than on my test bench.

To fix this problem, can I use a Positive Diode Clamp, as pictured below, in order to bring the bottom edge of the floating square wave to my circuit ground?

 

You need to connect the signal ground to your circuit ground. Is that not possible?

 

You need to connect the signal ground to your circuit ground. Is that not possible?

Possible, but undesired as I would have to tap into a control module in the vehicle and I don't want to disturb the factory wiring in the module.

 

Hello,

This is the second time we have to close a vehicle related thread of you.
This is your other closed thread with exactly the same circuit:
Op amp not responding in vehicle
Next time a ban will be the result.

Bertus