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Telephone Operating Power Flash Electrical Switch

2014-11-27 07:24  
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A telephone operated electrical switch for selectively energizing an electrical load in response to dialing of a predetermined telephone number. The electrical load may be the exterior light fixture of a dwelling, and the switch assembly may be configured to automatically flash the light on and off in response to the occupant dialing "9-1-1", so as to assist emergency response personnel in locating the dwelling.Tones (from the DTMF) on the telephone line are detected by Ul. When a valid tone is received, pin 14 (DAV) of Ul produces a positive pulse that is used to driveNAND gates U2A and U2B and then to latch binary data from Ul into Quad-D flip-flop U3 (Ul could be decoded into 16 bits, if required). The Q outputs of U3 drive optoisolators that control triacsTR1 , TR2, and TR3. PS1 is a 6-V 150-mA dc adapter that operates from 120 Vac.Theredundant ac-power switchis an optional feature that makes theSAN Volume Controllernodes resilient to the failure of a single power circuit.Theredundant ac-power switchis not a replacement for anuninterruptible power supply.
 

Telephone-Operated Ac Power Switch