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Topic: Getting sound level from audio jack (Read 1 time) previous topic - next topic

Grumpy_Mike

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Any ideas on what I am doing wrong?
Not without you posting a good picture of your wiring.

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On the packaging of the diode I am using it sais: 1N4001
That is a rectifier diode and while it will work the response is not so fast, so try a small signal diode like a 1N4148.

Also with a diode your audio signal needs to be above 0.7V for the diode to conduct.

Stabbler

Not without you posting a good picture of your wiring.
That is a rectifier diode and while it will work the response is not so fast, so try a small signal diode like a 1N4148.

Also with a diode your audio signal needs to be above 0.7V for the diode to conduct.
Thank you Mike.

I understand it is dificult to give an answer without a picture of the wiring. (It is also hard to produce a clear picture of the wiring.)

I will probably drive to the store to get the 1N4148. And see if that works. If it fails I will take another attempt at making a clear picture.

Does the signal also has to be above 0.7V for the 1N4148?

Grumpy_Mike

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Does the signal also has to be above 0.7V for the 1N4148?
Yes it is the forward voltage drop of a silicon diode.

Stabbler







This is my current set up.

Resistor = 100k Ohm
Capacitor = 0.22UF
Diode = 1n4148

I did not have the right colours jumper wires laying around, so this will have to do.
The blue wire is connected to A0 of the nodemcu, the yellow wire is connected to the ground.

With very load volumes I am getting a reading, otherwise I get no reading at all.

Can this be due to the fact that the diode only conducts when the voltage is above 0.7V?

Is there another Diode I can try whos forward voltage drop is lower?
Or should I find a way to amplify the signal?

Grumpy_Mike

Thanks for the pictures.

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With very load volumes I am getting a reading, otherwise I get no reading at all.
Well that shows something is working at least.
Try dropping that capacitor to 22nF or so and see if it improves.

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Can this be due to the fact that the diode only conducts when the voltage is above 0.7V?
It can in part but with such a small signal it is not going to be much good if you get a lower forward volts drop diode. You could either use a Schottky diode or a germanium diode but the volts drop is still in the order of 0.2V.

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Or should I find a way to amplify the signal?
Yes, look at getting an op-amp that you can run off 3V3 so you don't have to worry about sending too much voltage to the processor.

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