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Universal multi-function alarm and timer circuit using 555

Published on May 05 2011 // Timing control circuits

Universal multi-function alarm and timer circuit using 555.

Function as shown for the general alarm and timing circuits. The timing of the circuit can range from 5 minutes to 3 hours. Timing components C2, VD1 and VT1 multiplier circuit composed of capacitor 555. CK1 outlet from time to time 6 ~ 9V DC output voltage, time for radio work. K1 is set to the time block, press the AN, 555 ? pin output high (6 ~ 9V), while VT2 disconnected. When the timer time, the 555 3-pin goes low, CK1 no voltage output, VT2 turn, F1 and F2 20 seconds the alarm circuit to generate alarm and F3 to F5 generation of light alarm. A, B-side a variety of sensors can be attached to external sound and light alarm circuit.