I want a circuit that when receiving a signal coming from a microphone it turns on a led, such that the led on will indicate the signal frequency. Perr example, if the microphone detects an A a red LED will light up, if it's a B, a green LED will and so on.

It will have to be with a series of band pass filter(??), that's what I came up with, but I have had only a very basic class on circuits and haven't been able to come up with anything that will even begin to work, sorry.

 

I want a circuit that when receiving a signal coming from a microphone it turns on a led, such that the led on will indicate the signal frequency. Perr example, if the microphone detects an A a red LED will light up, if it's a B, a green LED will and so on.
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It will have to be with a series of band pass filter(??), that's what I came up with, but I have had only a very basic class on circuits and haven't been able to come up with anything that will even begin to work, sorry.

As you said, You would need filters. Band pass filters that are narrow enough to pass a single note is going to be tough and take a lot of components.

The other way of doing it is with microcontrollers and measure the time between zero-crossing events of your audio source. The problem with these types of "sensing" attempts, is the drum beats and other noise (even a second instrument of the same type, played just slightly differently, will increase the frequency count. An audio "tuner" works because you play only one note on one instrument at a time.

 

You can introduce a CTSS code decoder, as used in Two Way mobile radio, each microphone can transmit a separate undertone carrier (you can't hear the tone) the receiver can hear all inputs, but will only lock onto the strongest, and display its ID,. Unless there is a deadicated unit for this you're looking at a personalised microcontroller.


Ctss kits.

https://www.cstech.co.uk/ctcss-kits/ctcss-decoder-display-kit/

 

How many notes? I am not sure about this but you may be able to use a LM567 Tone Decoder. For example an A is 440 Hz so configure a 567 tone decoder for 440 Hz. The output of the decoder goes Low when the correct frequency comes in. The circuits could be tested using software like Audacity which is free. Not musically inclined so this is pure speculation and guess.

Ron

 

You can introduce a CTSS code decoder, as used in Two Way mobile radio, each microphone can transmit a separate undertone carrier (you can't hear the tone) the receiver can hear all inputs, but will only lock onto the strongest, and display its ID,. Unless there is a deadicated unit for this you're looking at a personalised microcontroller.

That would work, when I was searching I came across some ideas of microcontroller but was't sure it would be ideal or maybe over complex for what I had in mind, but I think that with a few adjusments like you said it would work pretty well, thanks.

 

How many notes? I am not sure about this but you may be able to use a LM567 Tone Decoder. For example an A is 440 Hz so configure a 567 tone decoder for 440 Hz. The output of the decoder goes Low when the correct frequency comes in. The circuits could be tested using software like Audacity which is free. Not musically inclined so this is pure speculation and guess.

Ron

It would be a fairly simple circuit, definitely with more than 3 lights but not one for every single note. Although it's a bit more than what I'm looking for, the tone decoder would work. Thank you!

 

As you said, You would need filters. Band pass filters that are narrow enough to pass a single note is going to be tough and take a lot of components.

The other way of doing it is with microcontrollers and measure the time between zero-crossing events of your audio source. The problem with these types of "sensing" attempts, is the drum beats and other noise (even a second instrument of the same type, played just slightly differently, will increase the frequency count. An audio "tuner" works because you play only one note on one instrument at a time.

Yeah, I see what you mean with the band bass filters. I suppose a simple color organ would work for now, but I have started looking into microcontrollers like you and another guy suggested. Thank you!

 

What is the source of the audio? Are the notes played individually or together? Individually will make for fewer errors. Note that there are guitar tuning devices that indicate when a note is correct, some as low as $5.

The 567 is an excellent tone decoder and relatively easy to tune to a specific frequency.

Because the bandwidth you want to detect is very narrow compared to the frequency, you will need a fairly high Q filter. Q is a measure of a filter's selectivity, the ability to accept/reject frequencies that are very close together. Middle-A is 220 Hz, while B is 247 Hz, a difference of only 11%. Instead of a standard bandpass filter, or highpass followed by lowpass, consider a notch architecture such as a twin-T.

ak