RF/EMI problems

i have an audio sampling device and both the microphone and the chip are picking up emi/rfi to the point where the audio is useless just high pitched noises , any ideas ? im using a 3.7v mp3 recorder that saves to sd with a small microphone

Hi,Andrew Feder,

Some solutions for your problem are given below,

1. Connect a22 ohms 2 watt resistor from your equipment ac power socket earth

terminal to the chassis of your equipment and connect the equipment chassis

to the dc negative supply of your power supply unit. The resistor acts as an

earth loop circuit dropping all the noise across it and preventing it from

entering your circuit.,also use a balanced in put connection for the mic .

2 . use transient voltage suppressor diodes (tvs diodes ) as per your voltage
requirement.
i am sure that your problem will be solved by point no 1 Regards Sambathkumar.

Hello , i greatly appreciatee your reply , this has basically eliminated the noise the pcb was picking up however the microphone is not balanced and is still picking up significant noise is there anyway i could make a balancing circuit with unbalanced output and input

Hi Andrew Feder,

Provide a 0.1mf and a 10 mfd 25v cap parallel to your dc supply be careful of
the polarity of the 10 mfd cap while connecting it. try this first, afterwards you can go for the balancing circuit. hope you review my rating .

Thank you,

Regards V.Sambath kumar.

where would i review your assistance ? this is the recorder im using http://www.waytronic.com/voice_module_show.asp?/42.html , you wouldn't happen to have a diagram for a balancing circuit would you ? im going to go to my local electronics shop in the morning there closed to day unfortunately?

Hi Andrew Feder,

I am sending one attachment this will clear all your problems.

pl check the attachment. Good luck.


Regards V.Sambath kumar

pl see the attachment .