The smallest combined electronic switch / linear regulator system for modelling !
Using the switch:
Hold the sensor button pressed in for about 0.5 seconds, and the LED glows orange. Now press the button a second button, and the LED turns green. The switch is now ON, and the circuit is ready for immediate use. To switch off, hold the sensor button pressed in again for about 0.5 seconds, until the LED glows orange. Now press it briefly a second time, and the LED goes out. The switch is now OFF.
When you initially connect the battery, the switch is always switched on immediately; the LED glows green.