Hand Clapper system!student project!

People, what else must i put into this circuit to make it work?
i want to make clap switch. Heres preliminary circuit to start me off

i don't think the trigger section built around the comp , will work properly ,
check by connecting a led to the o/p of comp and see the led turns off
only when clapped . as per the dia: the o/p will toggle randomly since there is no bias to the +pin (much like open).
todo: make the o/p of comp high all times and make it low when clapped.

The output of the comparitor is open collector; This means you must provide a pull-up resistor. Try something like 4k7.

The circuit is a mess:
1) The 2-wire electret mic's ground terminal isn't grounded and its output terminal doesn't have a 10k resistor to a 4V to 9V source for its approx. 0.5mA of current and to allow a few volts DC across it.
2) A comparator has a voltage gain of a few hundred thousand therefore can't be used as a mic preamp. It won't work anyway with its inputs a few volts apart and without a load resistor.
An opamp should be used as a mic preamp. It should have its input properly biased and have negative feedback (comparators can't have negative feedback). Its input should be coupled fron the mic with a coupling cap. Its output should be coupled to the trigger pin of the 555 with a coupling cap.
The trigger pin of the 555 should be held high with a pullup resistor.

Then the mic will work, couple its signal to the opamp mic preamp and its output will couple to the trigger input of the 555 for it to produce a timed pulse to clock the counter.
3) The counter's output will be random at power-up since it won't be reset.
4) The counter 's 7th divider's output will go high on the 128th hand clap.
The circuit doesn't have its ouputs gated to produce an output after only a few hand claps. Outputs of a ripple counter can't easily be gated anyway.
5) The circuit doesn't have a way to turn off the relay, nor a reset for the circuit to work the next time.[/img]

The circuit is a mess:
1) The 2-wire electret mic's ground terminal isn't grounded and its output terminal doesn't have a 10k resistor to a 4V to 9V source for its approx. 0.5mA of current and to allow a few volts DC across it.
2) A comparator has a voltage gain of a few hundred thousand therefore can't be used as a mic preamp. It won't work anyway with its inputs a few volts apart and without a load resistor.
An opamp should be used as a mic preamp. It should have its input properly biased and have negative feedback (comparators can't have negative feedback). Its input should be coupled from the mic with a coupling cap. Its output should be coupled to the trigger pin of the 555 with a coupling cap.
The trigger pin of the 555 should be held high with a pullup resistor.

Then the mic will work, couple its signal to the opamp mic preamp and its output will couple to the trigger input of the 555 for it to produce a timed pulse to clock the counter.
3) The counter's output will be random at power-up since it won't be reset.
4) The counter 's 7th divider's output will go high on the 128th hand clap.
The circuit doesn't have its ouputs gated to produce an output after only a few hand claps. Outputs of a ripple counter can't easily be gated anyway.
5) The circuit doesn't have a way to turn off the relay, nor a reset for the circuit to work the next time.
6) D4, D5, D6 and R2 (the second R2) aren't needed. When the output of the counter (or a gate) is low then the transistor is turned off through a series resistor. When the output goes high then the transistor is turned on through the series resistor.

is this any better?? never mind the reference names on the components!!

Hi Mossy,
Excellent! :lol:
Electret microphones have a wide range of operating current and pickup very low frequency sounds like trucks and anything rumbling. The current in my electret mics even change for a minute as they warm up.
Therefore I recommend adding a coupling capacitor from the mic to pin 3 of the opamp. Then the opamp's pin 3 will need a voltage divider from the supply to set its input reference voltage. The coupling cap and calculated parallel value of the resistors is a highpass filter that can have its cutoff frequency calculated.

Don't forget to ground the unused inputs of the other opamp in the LM358 dual opamp.

The half-wave rectifier isn't a voltage doubler. Its output will be the peak of the opamp's output minus a diode drop.

voltage divider on pin3 i/p pin of first op amp?

mossy said:

voltage divider on pin3 i/p pin of first op amp?

Click to expand...

Correct. Then a coupling capacitor from the mic.

Sorry but heres another varied circuit i'd like your opinion on.it does same job as othe clapper, or does it??

Do i not put voltage divivder on pin2??or does the pot and resisitors cover this? :?:

R2 plus R3 provide DC negative feedback so the opamp is a DC follower (of pin 3's voltage) with a gain of 1. R2 plus R3 together with R2 makes an AC voltage divider to set the AC gain of the opamp. The value of C3
is extremely low for the circuit to amplify audio frequencies.

The opamp won't work without the DC voltage divider at pin 3.

so if i have my dc voltage divider on pin 3 it should work ok?

what lenght pulse will come out of the ripple counter??how can i preset this lenght?

mossy said:

so if i have my dc voltage divider on pin 3 it should work ok?

Click to expand...

Then the opamp will be biased correctly but the value of C3 is much too low for audio.

what lenght pulse will come out of the ripple counter??how can i preset this lenght?

Click to expand...

Unknown unless the counter is reset when its power is applied. Then it will count 128 handclaps then give a continuous output for the next 128 handclaps before it shuts off. It needs another monostable for it to have a preset duration. Then the counter needs to be reset again for the next time to work correctly.