Security circuit for   Bikes, external water tanks gas lockers Ect just pass a wire loop through them. use it to operate most current sensing car alarms or add a latching relay. I have tried it on a sparkrite alarm and a easy alarm neither suffered from false activations

I have used this simple circuit for many years it is as versatile as you imagination I have not given the transistor values because it will depend on its  intend use. It is powered from the vehicle battery and only draws a few milliamps.  Two circuits  are shown using either a npn or pnp transistor the lamp in the circuit can be replaced with a buzzer ,relay  resistor it depends  on how you want to use the circuit .















Under normal circumstances the resistor makes a circuit via the security loop with the battery . Should the security loop be cut or door opened if reed switches are used TR1 now conducts and the lamp,  relay ect is energised.  Shorting the fake loop to the security loop will also cause a alarm condition

If you find this of interest please let me know


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