Latching relay

Ah, amazing what a bit of oxygen can do for cavitation. Now for the tractating coffee... So we're now at page 4. Hmmm... Dan, if you go down the 2-switch route, have you considered the classic SPST relay circuit (see eg capacitor value for latching relay? - especially the 8th reply - which has appeared many times since (eg, latching relay?) ...and beats this gem of an idea eh?). It uses any typical SPST relay and no circuitry excluding the diodes in case lower than load current switches are used, hence easy & cheap to source, build, & repair. For a single button toggle I like the old inverter circuit as per single button latching relay but its switch is circuit internal, ie NOT to GND or +12V. HotWaterWizard has some great circuits as per that last link and elsewhere tho some use multiple relays which I am not a fan of (I prefer circuit logic to relay logic). For a GND or +12V toggle relay there is also the 4017 based circuit. Tho IMO the "divide by 10" decade counter 4017 seems excessive as a mere divide by 2 counter it's nice because it can have a power-on reset feature and it's easily expanded to more than 2. Transistor or IC flip-flops would seem a more logical choice but I can see why some headlight relays etc use the 4017 instead - especially these days if web product information is so danged ambiguous, misleading or lacking!! Tho I'm not a fan of mechanically latching relays except where zero power draw is required (except when changing state) I recall liking the OMRON latchers that Howard referred to (low coil currents; small size; good specs, etc). If they are underrated they can drive normal relays. IMO that's preferable anyhow to keep heavy power short (ie, battery-relay-IGN) whilst keeping control nearby with short signal wires (and optional bypass/override switches) etc.