Cheap motorcycle alarm circuit.
During parking, hidden switch S1 is normally open and will not permit triggering of MOSFET T1. But when somebody starts the motorcycle by using ignition switch S2, MOSFET T2 triggers through diode D1 and resistor R5. Relay RL1 (12V, 2C/O) energises to switch on the alarm (designed close to IC1) as well as to disconnect the ignition coil from the circuit. Disconnection of the ignition coil avoids generation of spark from the spark plug. Generally, you will find there’s wire running from the alternator towards the ignition coil, which needs to be routed through one of the N/C1 contacts of relay RL1 as shown in the circuit diagram.
This schematic diagram come from circuit: Cheap Motorcycle Alarm
Go to that page to read the explanation about above circuit design.
In the electrical sector, a schematic diagram is usually used to describe the design or model of equipment. Schematic diagrams are usually utilized for the maintenance and repair of electronic and electromechanical devices / units. Original schematics were made by hand, using standardized templates or pre-printed adhesive symbols, but nowadays Electrical CAD computer software is often used.
In electronic design automation, until the 1980s schematics were virtually the only formal representation for circuits. More lately, using the progress of computer system technology, other representations were introduced and specialized computer languages were developed, because with the explosive development of the complexity of electronic circuits, classic schematics are getting less practical. As an example, hardware description languages are indispensable for contemporary digital circuit design.