output hum humdrum

[xray]

Howdy:
Looking for a little information on the increasing of the S/N. I have a portable electret microphone feeding a preamp and then to an adio output power amp, LM4860. My problem is as the power output of LM4860 goes up the voltage regulator LM7805 shows a ripple of the increased demand of the power out put. As the power goes up the ripple becomes amplified and can cause hum in the background or it gets large enough to oscilate the whole system. I've tried to place the preamps on a seperate Lm7805 from the single battery supply helped only marginally. Looking to create a silent background operation from the headphones while their is signal and no signal present at the mic. Any help out there would be appeciated.

Sincerely;
Cy Drollinger

 

[avishai]

What you need is in fact to disconnect the connection of the signal grounds between the amp stages .DO NOT MIX SIGNAL GROUND AND REGULAR EARTH SYSTEMS !!!!! After you separate those grounds you will have to insert an RFI-EMI filter (like Aerovox systems but you have different brand names

http://www.aerovox.com/prodindx.htm).Then

according to the type of installation you have you choose a T or Y filter and install it. A.Rash BScEE & PE
a_rash@bigfoot.com

 

[xray]

howdy folks:

I thought this would be a slam dunk for the very resource laden experts we have in this forum. I could list some handles of those I have read excellent responses from, but I would not want to forget anyone. I am inquiring on excluding an electrically generated noise from my audio output. I am guessing this is very possible for a good EE.

Thanks;

Cy Drollinger

 

[jbartos]

Suggestion. Generally, ripples are reduced by proper filtering. There are many different filters at different costs, and obviously from different filter specialists. Try some website for a right filter for your ripples, e.g.

http://www.thomasregister.com

and type Filters: Electronic under Product or Service which will return 198 companies to contact for right filter for your project.