GUARD SYSTEM Russian patent published in 1995 - IPC

FIELD: guard systems. SUBSTANCE: guide contact 12, which is unlocked when doors or windows are locked, prevents charged capacitor 12 against discharge to control electrode of thyristor 14. At unauthorized access, contact 12 closes and opens thyristor 14, as a result, voltage is applied to winding 7 of transformer 8 for short-time period. After that, thyristor 14 is kept at open position due to voltage of additional winding 18 independently on position of contact 12. Availability of voltage in transformer provides power of signalling system 24, which provides audible or light signalling. Guard system is driven into action by switch 3 when doors or windows are open. So, transformer 8 does not operate permanently in duty mode under voltage. Electron signalling system 24 is de-energized as well. EFFECT: improved reliability of operation; reduced fire danger. 2 dwg