This is a circuit to alert housemates that some one has opened the gate without using door bell.I have used 555 IC in Monostable Mode.To prevent permanent high at output pin3 I used a RC combination to trigger pin2 for a short time which times out approx 3 sec pulse at pin3 activating a relay and in turn a bell.
I am attaching the circuit (monostable circuit and relay at pin3 not shown).Timings are not critical.
My problem is that if I directly connect RC out to pin 2 of 555 nothing happens
therefore I Used buffer stage using Nand Gate ,transistor and relay.Circuit is perfectly working now.
I don't know much calculations and have only workable knowledge of electronics.
Please indicate flaws in the circuit, your suggestions are welcome.
I am attaching the circuit (monostable circuit and relay at pin3 not shown).Timings are not critical.
My problem is that if I directly connect RC out to pin 2 of 555 nothing happens
therefore I Used buffer stage using Nand Gate ,transistor and relay.Circuit is perfectly working now.
I don't know much calculations and have only workable knowledge of electronics.
Please indicate flaws in the circuit, your suggestions are welcome.
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