The burglar-alarm system circuit of LED

Published:2011/5/26 22:31:00 Author:Borg | Keyword: burglar-alarm system, LED | From:SeekIC

This is a burglar-alarm system circuit of LED. To enlarge the alarm range, the circuit is installed with two LED as the light receiver. The light resource is a infrared ray LED, to reduce the interruption from other rays, it needs to modulate the LED ray. If the beam of the LED is shadowed, the NPN of VTI stops work, and CI generates electricity through VD1, and the base electrode of VT3 is provided with current and VT3 is passable. In the meantime, the single stable circuit consisting of VT3 and VT4 is in a temporarily stable state.



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