“The watchman”, whose scheme is shown in figure 4, is an electronic relay with two stable States. When wrapped around the protected sheathed car wire L1 is intact, the transistor V1 is closed, relay K2 is de-energized, the audio signals B1, B2 off. Upon breakdown of the protective wire of the transistor V1 open, relay K2 releases and contact K2 of the plate.1 short circuit relay K1 sound car alarm: signals B1, B2 are enabled.
Fig. 4. The first version of “guard”
Fig. 5. The second version of “watchmen”
Relay K2 — RES-9 (passport RS4.524.202), S2 — toggle switch T1, L1 — a wire PEV-2 0,1.
After checking the correct installation select the value of resistor R1.
The second option is the “watchman” (see figure 5) is a set of contacts S3 — S8, each of which, hinging leads to relay K1 system sound alarm car. For reliable actuation of the contacts S3 — S8, it is recommended to saublebeach.
Assign switches: S3 — hood, S4 left front door, S5 — the right front door, S6 — left rear door, S7 — right rear door, S8 — trunk.
S2 — toggle switch T1, S3 — S8 pushbutton switches of any type, designed for the tension of 12 V and a current of 500 mA.
All the schemes are tested on the car “Moskvich-2140”.