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Flashing Signal Alarm with LEDs Circuit

2014-12-19 17:43  
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Flash signals for the AO-543 modules are derived form the fast- and slow flash outputs. The fast flash signal is generated by a oscillator circuit.A LED  flashing briefly once every 5 seconds to imitate the indicator of a real alarm is the function of this dummy alarm project with the use of a 7555 timer IC.This circuit is useful if you need a low-energy flashing alarm. The 200 to 400-dc supply should have enough internal resistance to charge the 0.5 capacitor between flashes, about 2 or 3 time constants, which means about 500 kQ to 1 for a 1-s rate.Use lower values for higher rates.The Signalalarmfunction shall cause the system to generate a SIGALRM signal for the process after the number of realtime seconds specified bysecondshave elapsed. Processor scheduling delays may prevent the process from handling the signal as soon as it is generated.

Flash Signal Alarm Circuit