E-the guard mounted on the car “Lada”, emits intermittent alarm signals if someone opens the door, hood or trunk of a car.
How does such a device? The position switch B1 on the diagram (Fig. 1) corresponds to the mode “waiting”. Suppose you open any of the doors, and the contact of the limit switch is closed to the vehicle body. Relay R1 and cambiocorsa its contact R1/1. If you now close the door (limit switch open), the circuit remains switched on. When the relay coil R1 is energized, capacitor C1 is charged through the resistor R1. 4-5 with the voltage on C1 reaches a value at which the transistors T1, T2 and relay R2. It someblokelol (P2/1) and through contact P2/2 energizes the circuit of the relaxation generator (T3, T4). Contacts RH/1, RH/2 relay R3 included in the circuit of the horns. The frequency of the signals depends on the parameters of the chain R4, C2. When closed contacts of the limit switches of the hood or trunk, relay R2 and energizes the transistors T3, T4.
Fig. 1. The concept of “watchman”.
In order to get in the car, the driver needs 4-5 to disable the alarm toggle switch B1: it is time for the “watchman” has no time “to vote”. Before leaving the machine, this toggle switch you want to enable and click on KN1. The capacitor C3 is charged, and the transistors T5, T6 are unlocked, including the relay R4. The contact R4/1 opens the power circuit to the schematic 10-30 E. This is enough time to slowly get out of the car and close the doors. When the capacitor C3 is discharged, the transistors T5, T6 are locked, and the contact R4/1 is closed. Since then, the alarm device is in the standby mode.
DESIGNS AND DETAILS
Electronic “watchman” is mounted on a printed circuit Board size 155X65 mm (Fig. 2). Toggle switch B1, and the Kh1 button set in a hidden place, and the Board is placed in the cab or in the engine compartment. It is housed in a metal casing size 175X85X50 mm. In its lateral wall has seven terminals through which the circuit is connected to external devices. The cross section of the wires leading to clahsen must be not less than 1.0 MM2: the current in the circuit varies from 7 to 10 A.
On the car under the hood and in the trunk you need to put limit switches, for example from the refrigerator. You can use a regular switch under the hood, “Lada”, but then you have to disconnect the wire that supplies voltage 12V lamp engine compartment.
Fig. 2. Printed circuit Board signaling with location details.
In the circuit of the alarm device D1—D7 can be replaced by diodes D7 with any alphabetic index.
Resistors — MLT-0,25, condensers — K50-6.
R1—R4 — relay RES9 (passport RS4.524.202). Instead, you can use any other with a coil resistance of 400 Ohms and a current not exceeding 30 mA.
Using resistors R1, R6 are selected exposure time switch on the transistors T1, T2, and T5, T6. The frequency of relay R3 regulate by changing the parameters of the chain R4, C2. The response time of the alarm when opening the door of the car (4-5 C), set by resistor R1; the terminal Кл2 and Кл5 connect. Further facilities include a relaxation oscillator (T3, T4), and select the length of the horns: 0.5 s. In conclusion, to achieve that the alarm device is triggered through 10-30 s after the driver gets out of the car. This operation simulates closing terminals Кл2 and Кл4.