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[SOLVED] Sound Detecting circuit

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motoshan

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Hello all..
I would like to ask a question regarding a circuit that must produce some output upon detecting some sound signal.ill describe in detail...

  • consider there exist a system
  • the system must accept an input sound from mobile phone(just imagine as a "LONG BEEP" and "SHORT BEEP")
  • Now i want to switch-on RELAY1 for the "LONG BEEP" and Switch-on RELAY2 for "SHORT BEEP"
  • And Switch-off the Relays , if once again it receive the corresponding BEEPS
  • how can i implement this system


Please guide me in right path.Iam a computer science student and i hav a software + hardware project to implement.I knew that there is some clap-switch circuits, But these clap switches just switches according to the input pulses No comparison is there..
 

u could try dtmf

hxxp://www.circuitsgallery.com/2012/07/dtmf-dual-tone-multi-frequency-decoder-circuit-schematic-using-m8870-ic.html
 
phobos1 said:
u could try dtmf

hxxp://www.circuitsgallery.com/2012/07/dtmf-dual-tone-multi-frequency-decoder-circuit-schematic-using-m8870-ic.html
Click to expand...

Thanks for the Kick Start!!!!:razz:
 

After following DTMF technique. I had built a circuit successfully!! It uses a decode IC and a D flipflop. But my question is why should we use a D Ff here since we hav a high out put on corresponding BCD pins on the decoder IC.Can i connect the relay directly to any of these output pin?

When i press key 1 the decoder decodes it and the Q1 will bethe only pin in high state.so my question is is it safe to connect relay diretly to this pin?
 

motoshan said:
When i press key 1 the decoder decodes it and the Q1 will bethe only pin in high state.so my question is is it safe to connect relay diretly to this pin?
Click to expand...

Connect pin directly to relay ? You wanna burn your ICs and other components.
You need to output it to proper resistor to the base of switching transistor which can take relay load
Relay coil will have protection diode in parallel. Check for polarity as it will be connected reversed.

You can use relay driver ICs also but I have not yet tried any
 

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