Hi! I am taking an AM 8-track car radio and converting it to AM/FM. I need to use the track selector switch, it is a momentary switch, and turn it into a latching switch or use a relay to latch and unlatch a ground output.

Any help would be great! Thank you.

 

You can do it with a logic circuit called a toggle flip-flop.
Firstly, you need to debounce the momentary switch with a filter circuit and a Schmitt trigger.
Then you apply the clean signal to the clock input of a T-type flip-flop (created from a J-K flop-flop). From the output of the flip-flop you can drive a transistor or a relay.

 

Don't know how complex you want to get, and whether you know enough to build the circuit recommended by MrChips, buy here's an alternative design. It uses simple circuit & cheap 12v relays:
http://www.emil.matei.ro/onof2.php

 

Denesius, thanks a lot! They all look good, but those end results are gating power. I need to gate the ground through, but I think I can manipulate it to work.

 

You can do it with a logic circuit called a toggle flip-flop.
Firstly, you need to debounce the momentary switch with a filter circuit and a Schmitt trigger.
Then you apply the clean signal to the clock input of a T-type flip-flop (created from a J-K flop-flop). From the output of the flip-flop you can drive a transistor or a relay.

Any chance you have a schematic for this?

 

Here is a conceptual circuit, not tested: