Is there a relay or SSR that the trigger voltage is adjustable between 0.5vdc and 4.5vdc.
I want to use voltage from a automotive gauge to trigger a relay or SSR to activate a buzzer to warn the operator.
This would be for oil psi, oil temp, ECT, Trans temp, etc. etc.

 

Will this work for you?
Voltage level relay

 

Is there a relay or SSR that the trigger voltage is adjustable between 0.5vdc and 4.5vdc.
I want to use voltage from a automotive gauge to trigger a relay or SSR to activate a buzzer to warn the operator.
This would be for oil psi, oil temp, ECT, Trans temp, etc. etc.

Not a relay. But you can use a comparator or opamp to drive an SSR.
The trigger would be adjusted via a reference voltage to the comparator.

 

"This would be for oil psi, oil temp, ECT, Trans temp, etc. etc."
I just noticed this. Do you want to detect voltages from multiple devices but yield one warning output? Or do you want a separate warning for each device? This might be a solution: https://www.amazon.com/LIVISN-Compa...=8ch+voltage+comparator&qid=1606851401&sr=8-1