Having a few engines laying around the garage and in Mokes in unknown condition saw me building a general purpose control panel that is used to turn over an engine so I can do a compression test or see if the engine is seized. The Black button on the right is connected to the Starter terminal on the solenoid using a White with Red wire.
The big Red Key is a battery isolator in emergency or for making adding new features safer.
The red switch on the top right is the Ignition switch and is a simple rocker switch that lights up when the ignition circuit is on. A wire from this goes straight to the '+' side of the coil.
The two Amber lights are Oil and Alternator indicators and are connected to the ignition circuit and run to their respective terminals on the Oil pressure switch and the back of the Alternator
The voltage gauge is fitted but at the time of writing it is not yet connected, despite what it might display!