Wireless Caller Amp Feedback Fix

A

ArkansasElkHunter

New member
I built a Wireless caller with a Nady 151 and when I added a Radio Shack amp, I got some nasty feedback through the speaker. It did not do it with a seperate power source for each, but when I combined them I get a loud Buzz if there is any amp volume at all.

I added an Isolation Transformer to the amp and the problem went away. Catalog #: 273-1374
It's $3.99 and a store stock Item at Radioshack. You Simply wire it to the battery and then to the amp.

I also took the Amplifier out of the original housing and put it in a 4AA battery holder, Fits like a charm. Cut a slot for the volume knob and holes for the input and output jacks. You can see the transformer in the picture (little green square)
amp-open.JPG
amp-closed.JPG


Hope this helps someone, sure worked for me.
 
Hmmm. I just finished putting together my first 7W Velleman amp and have a simular problem. The speaker is quiet until I play the MP3. I get allot of white noise. This doesn't happen with the radio shack amp and 9V battery. When I add the Nady, it gets a little worse. Did you have any white noise (static) with your Velleman amp?
 
I just ordered my Velleman amp yesterday as a kit. I am also looking at getting a Nady 151. I'll have to keep this in mind when I put it all together.
I have a question for anyone who has this amp about the volume control. I was wondering how it works since it looks like the only way to adjust the volume is from the player?

Mike
 
I placed a 10 microfarad, 50V, electrolytic cap from pin 1 of IC1 (the + input to the amp IC)to ground. Make sure you get the polarity right. That made the output of the 7W amp crystal clear. All the white noise went away. That is with my MP3 connected directly to the amp. Gonna check it out with the NADY tonight.
 
Originally posted by weeble wobble:
[qb]I placed a 10 microfarad, 50V, electrolytic cap from pin 1 of IC1 (the + input to the amp IC)to ground. Make sure you get the polarity right. That made the output of the 7W amp crystal clear. All the white noise went away. That is with my MP3 connected directly to the amp. Gonna check it out with the NADY tonight.[/qb]
Click to expand...
Weeble Wobble,

Did you ever get around to testing this with the Nady? I looked at Radio Shack's site and I was wondering if this #272-999 is the model number? I was also wondering if you have a gain for the amp or do you just rely on the MP3? My 7w Velleman kit arrives tomorrow so I'm looking at setting it up the best way from the start.

Mike
 
Sorry, I've been away. I will take pics and post them tomorrow. It is a simple mod to the amp and it made all the difference in the output with and without the Nady stuff.
 
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