Sending voice to Nokia

[thirsty003]

Thanks for the reply guys. This is a link to where I got the wiring for the 2.5mm jack - http://pinouts.ru/CellularPhones-Nok...t_pinout.shtml

I'm using a stereo plug and I'm using the base and middle landings which I think is correct. The output I'm using from the opamp should be a large enough signal for the Nokia.

I guess I'll just need to experiment some more to find the right connections.

Regards

Tony

[inse]

Hi Tony,

are you using a 8210 cell phone for your project?
As the three pole plug seems to be used there only.
Do you have a common ground on the phone and your circuit?
Then you should check if MIC- is on ground potential.
Futhermore I don't think you will need a "strong" signal, as a microphone would not deliver more than 100mV (guess) signal.
Make sure not to overdrive the input.

Regards,
Ingo

[thirsty003]

Hi Ingo,

The phone I'm using is new (not sure what the model number is) and it uses a 4 pole socket but using a 3 pole plug should work 'cause when I plug it into the phone it recognises that a handsfree is in use.

I've connected the mic- to ground in my circuit and used the output direct from the ISD4004 but no good yet. The output from the ISD is quite low - I haven't measured it but I think it's only around 30-40mv. The gain from the opamp is about 10 so the output is quite a bit higher there.

Even so, I still get nothing out of the phone.

I'm going to keep experimenting - I should get it soon.

If I plug an earphone into the socket I should be able to hear if something is going into the mic should i not? That way I can save some money by not having to call the mobile to test it.

Thanks again,

Regards

Tony

[inse]

Hi Tony,

if you look at the pinout you have posted, you will see that using a three pole plug would short the microphone input to the speaker output...

Try to get an appropriate connector first.

Regards,

Ingo