555 Timer DC Protect / Turn-On Delay

Thanks for pointing the option out prasi. I'm aware of ICs like the one you mention but not actually interested. I liked the idea of the 555 because it has much of the functionality we require, exists in virtually every market globally and is cheap.

As for the AC loss detection, A couple more components would give output muting within a few cycles of AC loss and would likely be worth implementing.
 
The AC detect, or loss of, can detect just one missing pulse, i.e. it starts to activate the loss of AC drop out within 10ms.
The missing pulse transistor is kept off when each halfwave pulse arrives.
If that pulse does not arrive it pulls the timing cap low and triggers the OFF.
A full timing cycle has to complete before the ON can be timed in.
 
Hello

Hello
greetings circuit posted is a simple dc detector i want to add short circuit
overload protection to it Q4 Q6 can a simple latch circuit be added to the
existing circuit if triggered remains off till it is reset maybe someone
can help me out overload circuit can be designed using opto PC817
and a 8 pin comparator ic many overload circuits use voltage drop on
emitter resistance but when we short the speaker wires relay goes on
and off want relay to remain latched till speaker wires are removed

warm regards
Andrew😉
 
Hello

oops forgot to post the schematic
 

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Hi,
I do not want to discourage you but why you don't use a micro controller like the Basic Micro Nano8. It is an 8 pin dip chip with 4 programmable ports. The ports can be programmable as I/O, analog input and pwm. I called it 4 programmable LM555's. Any body can program it with simple basic commands.

Here it is a simple program example that can be use to delay the mute. Also attached it is the circuit drawing.

Main

High P1 'Enable mute relay this will disconnect the speaker
pause (4000) 'Delay for 4 second --- 1000 = 1 second
LOW P1 'Disable Mute relay this will connect the speaker
end
 

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Hello

Hello Tomas
greetings thanks for the information its hard to get parts here
in my city so i try simple circuits i have ordered some parts
waiting for it to arrive i think protection will work right
warm regards
Andrew
 

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Hello Tomas
greetings very sorry for not replying yes i got the email will try it out
as for the short circuit protection its working both the ACS and the opto
817 might make a vedio tomorrow of the vedio showing short circuit
protection i rather keep it simple than running around for exotic parts
only the solid state mosfet relay is left to be made low RDS mosfets
costly and hard to find here will keep you informed
warm regards
Andrew
 
The joy of Doing It Yourself is: you can do things your way. Don't like the PCBs that are commercially available? No problem, make your own circuit and while you're at it, build it however you like. PCB is only one possibility among many!