Quick question about a Voltage Comparator

Owen

Friend of mine has asked me to build him a circuit to fix his heater controls in his Ford Puma. There's a signal which is sent to the heater control unit which should flop between 12-14v and 0 depending on temperature of the car, but because his one is faulty, instead of dropping to zero, it drops to 9v.

My initial thought was just to use a relay as a voltage based switch, but most relays will accept 8v as a minimum input, thereby activating the circuit permenantly.

I've roughly layed out a circuit using a comparator circuit, but was wondering if something like an LM393 could accept the high voltages such as 14v on it's inverting/non inverting inputs?

Inspector Gadget

Not having any details to go on other than your description, the LM393 is specced to run to 36v in a single-sided configuration (i.e. a single supply and ground rather than a positive and negative supply), so that's not a problem as long as the supply voltage is equal or higher than the input levels, as far as I remember.

But I have no idea what kind of input you're passing in (voltage range, current, etc.) or what the output needs to drive (relay, transistor, etc.) so I can't express certainty.

Hope that helps,
Gadget

Owen

Definitely definitely helps. Thanks Gadget!