THE “GUARD” DOORS

The scheme is simple electronic guard device published the magazine “Funkamateur” (GDR). Across the doors of the protected object stretched thin wire. Until he is whole, the tension on the bases of the transistors VT1—VT3 are few and they are closed. In case of wire break on VT1 through a resistor R2 receives the bias voltage, and this semiconductor device is opened. Now, through a chain of R2—R4, the transistor VT3 will get more offset. Relay K1 will work, and its contact system will include a siren, a buzzer or a lamp. Moreover, the elimination of wire break will not change the situation is to disable the watchdog is possible only with the switch ЅА1.

 
 
The device can be applied to domestic transistors series КТ342, KT315 (VT1), KT361, КТ203 (VT2) with h 21E> 100. The type of transistor VТЗ selected depending on current of the relay K1, for example a series КТ603, KT315. The diode VD1 — D226 with any alphabetic index.

Recommend to read

  • SHELVES FOR BOTTLES…SHELVES FOR BOTTLES…
    In this mounted mesh shelf is very convenient to keep stock of a wide variety of drinks in bottled packaging—from soda and wine to yoghurt. They are visible at all times, easily...
  • BRAKES? ON THE CHECK!BRAKES? ON THE CHECK!
    Many accidents occur due to technical reasons, including due to faults of the brake system of the vehicle. One of the indicators of the effectiveness of this system is the braking...