The control unit uses this signal to activate the switch/relay to turn equipment on or off.

For example, in order to activate a switch, players must first open a safe and use the matches found within to start a boiler.

Fortunately a felt-tip pen was sufficient to activate the switch.

To accomplish this the pilot activates a switch or mechanical handle in the cockpit, which releases the up-lock.

Some variants employ a simulated bag, wherein the player's pressure on the bag activates a switch maintaining a constant tone.