Found in a 1980s documentation, this circuit works with a 12V relay. The horn is the boat's own.
When the input voltage is higher than 2/3 of the power supply voltage the green LEDs glows. When...
This is a conventional alarm that uses NO and NC type sensors for doors and windows. The circuit is...
This circuit was obtained in a 1972 RCA power transistors manual. The transistor admits...