Voice activated relais with Arduino

Hello,

I need to build a circuit that will get its input from a telephone line. When I have sound/voice in the line above noise level, I want to get an output capable of sending it as an input on an Arduino (nano). When the sound/voice goes off and there is noise level again, to get another ouput, capable of sending it as an input on an Arduino...I want to control a relais with the Arduino...

Thank you...

A normal landline has about 50vdc across it when the telephone is 'on hook' ie not lifted
An incoming call supplies a 25Hz or so 70vac signal to ring the bell.
When the handset is lifted the voltage drops, the bell tone disappears, and the incoming caller can be heard.

Only at this third stage would voice detection be useful .

How can we or an arduino help you?

Allan

Ok, to put it in a better description, if it is not telephone line but voice inside telephone line frequencies??

Did we not go into this in some detail recently ? - I even suggested a little preamp which you tried and said worked....

Allan

allanhurst:
Did we not go into this in some detail recently ? - I even suggested a little preamp which you tried and said worked....

Allan

Yes, it worked with sinusoids, when I tested it with voice/sound it didn't work, and I do not know if I can make it work with sound/voice...

Thank you...

Do you know how big a signal your sound/noise provides? Below a certain threshold my device will do nothing and you may need more amplification.

Allan

allanhurst:
Do you know how big a signal your sound/noise provides? Below a certain threshold my device will do nothing and you may need more amplification.

Allan

The signal will be (0,5 - 1,5 Vpp) @(300Hz - 3000Hz). A typical sound of a 14400 bps old modem..

Is it so difficult what I am asking/trying to do?

If you nag you'll get nought. We all have other jobs to do.

In any case I gave you the answer many posts ago.

Allan

Hello…

I tested this circuit (please see attachment) with audio from youtube.

The first test was from audio from mobile phone. Although I maximized its sound output on the ear jack, the signal was too small to be detected by the circuit.

The second test was from audio from the laptop. Again I maximized the sound on earphone output, and this time the sound was detected by the circuit.

In both cases I used an audio jack where I connect the two wires to the input of the circuit.

So I believe it’s a kind of amplifing the circuit before feeding the input. Is there any low cost solution to amplify a signal of about 0,2 - 0,3 Vpp to 0,5 - 2,5 Vpp?? I use up to 12 Volt supply. Can I do the amplification with Arduino nano?

Thank you…

New shortcut.lnk.pdf (18.3 KB)

The enclosed will work from a few tens of mV. Mess about with R3 for highest sensitvity

Allan

apre.pdf (17.7 KB)

Hello...

It works from the audio jack from the laptop, using half the volume of the previous circuit. When I use sound from the cellphone, it does not. So generally it works. Thank you...I used a pot 5k instead of the 680 Ohm.

If anyone has an idea...when I have sound above 300Hz the Arduino should wait.. and when the sound does below 300 Hz it should give a signal to the relais to close it. The problem is that the sound is not on-off but has many variations.. I want when the sound goes below 300 Hz for let's say 10 seconds, then to give signal to the relais. What do you suggest? How would you implement that?

Thank you...

After the signal and before the above (comment #9) circuit, I am thinking of connecting this amplifier:

Will it make any amplification? Can it drive the #9 circuit?