555 circuits 6

Posted on Feb 7, 2014

The heart of this circuit is IC No. 555. When the alert sound was working, even though the switch will continue to be the same, the sound still does not stop immediately. But it will stops automatically, when a set time period, Depending on the resistance of R3, the circuit so I set a time period equal to 1M for 1 minute 6 seconds. The output of IC

555 circuits 6
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555 is triggered by a positive voltage on pin 2, when all switches are connected together. When the something switch is cut off pin 2, it will be negative voltage and the trigger IC 555 will stop. The C1, C4 to protects a noise signal from either switch, which may cause the alarm to be up. This circuit can be used with power supply from 5V to 15V depending on relay sure enough. This circuit is intended to let the user turn off a lamp by means of a switch placed far from bed, allowing him enough time to lie down before the lamp really switches off. Obviously, users will be able to find different applications for this circuit in order to suit their needs. Due to the low current drawing, the circuit can be supplied from 230Vac mains without a transformer. Supply voltage is reduced to 10Vdc by means of C1 reactance, a two diode rectifier cell D1 & D2 and Zener diode D3. IC1 is a CMos 555 timer wired as a monostable, providing 15 seconds on-time set by R3 & C4. When SW1 is closed, IC1 output (pin 3) is permanently on, driving Triac D4 which in turn feeds the lamp. Opening SW1 operates the monostable and, after 15 seconds, pin 3 of IC1 goes low switching off the lamp Operation of the circuit is when the power supply to the circuit. It will give birth to high frequency by using a circuit IC1 to a multi-state Devices Bill Brett Foster. The frequency with which R1, C1 and C2. The frequency will be out in three legs. And will be...

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