K is the merrcury conductive switch, and S is the power switch linked with the car key. After the car stops properly, put the switch in the "OFF" position, and then pull out the key. At this time, the two contacts in the merrcury conductive switch K are disconnected, and the "2" pin of the input terminal U1A is at a low level, so the "3" pin outputs a low level, the diode VD2 is turned off, and the transistor VT1 and the other diode VD3 are also turned off. The input pin "6" of U1B is low level, so the output pin "4" outputs low level, transistors VT3 and VT4 are turned off, and alarm horn B does not sound. If someone moves the car, it will inevitably cause vibration, so that the two contacts in the merrcury conductive switch K will be instantly closed, VD1 will be turned on, and both input terminals of U1A will be at high level, and the "3" pin will output a high level, so that VD2 will be turned on, and the capacitor C1 will be charged. At the same time, VT1 will be turned on, and the emitter will output a high level, and the "6" pin of U1B will be turned on by VD3, and the "4" pin will output a high level, which will be passed through VT.

When the owner drives, first insert the key and turn the switch to the "ON" position. Positive current is injected into the base of VT2 through VD4 and R10, so that VT2 is turned on, thus clamping the "6" pin of U1B at a low level, and U1B is blocked. At this time, no matter how to move the vehicle or drive, the alarm will not sound because the "4" foot of U1B remains low all the time.

Specifications:

Product name: motorcycle burglar alarm
Product size: 40*55MM
Working voltage: DC5V

Package Include:

1u00d7 Motorcycle Burglar Alarm DIY Kit