Push-button ON/OFF

In order to start the Peltier-based car freezer and to make sure that it turn off and stays OFF after the car stopped (a big Peltier is a huge battery drain!), I've made this 4-relay based circuit. No or "as little as possible" electronics in the car is the best approach - only the aerospace is harder for electronics than automotive - the best solution might involve some relays and, maybe, a couple of diodes, but stay away from amateurish electronics in the car! This is the diagram I draw on the back of a napkin (as usual) :)

Tehnium 08-09/1995 (romanian language) :)

Yes, there was a time when I was doing everything analog. Then it came a time when even my audio amplifiers where "Class D" and I designed way smarter digital security systems based on real microcontrollers (among many other things), but I will always remember with pleasure my first successful (as in "I sold more than 10" :) ) product: