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Old 1st August 2012, 08:06 PM   #1
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Default Chip Amp buzzing problem

Hey all, just got done building my first chip amp and it works great, except for one thing- it buzzes/hums incessantly. I have jury-rigged a power supply with small alligator clips to an old AC adapter until I can go to radioshack to get a proper setup. Is the buzz/hum a product of this rig, or is it something else, such as a bad connection somewhere or a grounding issue? I have checked the pcb and all of the components seem to be properly soldered without any bridging between leads. And yes, the adapter's output is withing the correct operating range for the amp. Thanks for the help.
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Old 1st August 2012, 10:09 PM   #2
johnr66 is offline johnr66  United States
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Try shorting the input to ground to see if it stops. You really need to provide a schematic if you want help. It could be one of many things even bees :-)
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Old 2nd August 2012, 02:40 PM   #3
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What chip amp you are using now for your project?

Buzzing can be caused by improper bypassing at the Chip amplifier, or bad grounding or even can be caused if your heatsink is not grounded.

Is your power supply is properly grounded? It should be using a star grounding for the power supply for an amplifier.
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Old 2nd August 2012, 06:26 PM   #4
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Click the image to open in full size.

Heres the schematic, its a pretty simple design. I tried grounding the input, heatsink, and the power supply as you suggested and it decreased the noise somewhat. However the noise is still noticeable with all of them grounded. I might try the star grounding method if you think its worth a shot. Thanks once again!
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Old 2nd August 2012, 07:10 PM   #5
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You should do star grounding.
That will help.
Read the guides found on this forum for more information.
Allso, watch out for proper connection of the volume pot.
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Old 2nd August 2012, 11:47 PM   #6
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ya forget something important ... did u ground metal body part of your potentiometer (volume control)?
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Old 3rd August 2012, 03:21 AM   #7
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I currently dont have a pot connected to the input since one wasnt included in the kit. I'm gonna try star grounding with the power supply and heatsink, those seem to be creating most of the buzzing. Thanks for the help!
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Old 3rd August 2012, 12:21 PM   #8
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then ... if that is the case ... i will suggest to look at and try to improve on the power supply section first ... if you really want low noise supply ... then try to increase the capacitance ... maybe to about 22000uF and see if it does improve matters or not

Another thing, C12 should be located nearby (but not touching) with the IC chip amp ... did u did that?

And it might be helpful if you can take a picture of your amp and i can see what i can help you on this matter ...
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Old 3rd August 2012, 12:34 PM   #9
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Quote:
Originally Posted by guitardiy View Post
I have jury-rigged a power supply with small alligator clips to an old AC adapter
Theres the problem.
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Old 3rd August 2012, 01:10 PM   #10
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hmm...
change c11 to 220 pF.

if You do not connect this amp to any source, does it hum?
if it does afterwards (changeing the c11) , then a pot will fix its issues.
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