A simple and easy way to create an open door alarm for your car door.
Materials Tools:
-usual old chinese alarm clock
wire
soldering iron
-battery
The manufacturing process of an open door alarm device.
This method of creating a tweeter for the door is really very simple, since it does not require the creation of any schemes, which means that the technology is available to almost everyone.
Basis for homemade served as a standard old alarm clock with a rather nasty squeaky call. It is this circuit with the squeaker that will be needed to create the door signaling device.
Step one: dismantling the alarm.
Getting the circuit is quite simple by unscrewing the bolts and disassembling the Chinese alarm in this way, as shown in the pictures.
Step two: prepare a signaling circuit.
The alarm clock circuit has two contacts through which it will be connected to the gap of the open car door. But for this you need to first solder two wires of sufficient length to the contacts of the circuit. This process is well illustrated in photographs.
After that, the main part of the alarm device will be ready for placement in car. To make it sound when the car door is open, the device should be connected to the door limit switch. The image below shows this schematically.
Step three: install the device in the car.
As can be seen from the attached diagram, the yellow wire connects to the trailer door, and the author, in turn, connected the red wire to the plus power of the battery through a 10 kΩ resistor.