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General multi-functional alarm and timer(555) circuit diagra

2015-01-04 12:51  
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General multi-functional alarm and timer(555) circuit diagram
General multi-functional alarm and timer(555) circuit diagram is shown as above. The timing range of this circuit can be adjusted from 5 minutrs to 3 hours. 555 Capacitor multiplier circuit is made up of timing components C2, VD1 and VT1.For keeping K1 at timing block and press AN, 555③ pin will output high level(6~9V) and VT2 will be disconnected. When it's time to timing time, 555's pin 3 will turn to low level. CK1 will have no voltage output and VT2 will be conducted. The alarm circuit composedof F1 and F2 will produce 20 seconds alarm ,and F3 to F5 will produce light alarm. A and B ends can be added a variety of sensors to make up of an additional acoustic and optical alarm circuit.