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Circuit not working? Answered

Hey Guys, a few weeks back I posted a question about a clap switch with an IC 4017 not working (relay not turning on). Well I tried to make the project again. The problem is now the relay wont turn off (-_-). (https://www.youtube.com/watch?v=zFu0pBvpmIk) video of the project by another guy ( He doesn't use relay, instead he uses an LED. The problem with mine is that when I give it power the CIRCUIT OFF LED is off and the relay is on, indication that the circuit is in on position, so far so good. But when i clap the CIRCUIT OFF LED turns on indicating that the circuit is off but the relay stays on. The first time I tried, i didnt put the diode near the relay, same result. THen I put a diode (the wrong way), nearly burnt my hand. This time i put the diode in the same way that im supposed to but the circuit still has the same result. I have uploaded the schematics, Hope someone can help me.


I was using MJE13003B instead of BC547. When I was using the mje13003b it was very easy to turn the circuit on and it used to come on at first try. When i inserted the BC547 the circuit was in off position I clapped and it worked like a charm the indicator led turned off and the relay turned on. But when I tried to turn it back off, everytime i clapped the status led blinked and thats it, It just blinked, the circuit would be still in on position. I wonder whats the prob since turning it on is easy and turning it off is impossible.

NOTE: Now its the same with the on position. Whether its in on or off position same thing happens. In one of the million clap it turns on.

Thanks in advance.
-Prickly Potato



Best Answer 3 years ago

The event, that nearly burned your hand (hot diode) also probably destroyed the NPN transistor BC547 by the same excessive current.


Answer 3 years ago

First thing, it fixed by itself. Second thing, the mosfet was connected at the time. But thx for the help. I'll just mark your answer best answer instead of closing the thread :).


Answer 3 years ago

The CO pin-12 MUST be left open and an integrator function added to the op-amp may avoid a clap running multiple clock pulses to the 4017.

try 1k and o.47uF and try other values.

If you don't have a scope ..... FORGET R5 C1...