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Tonepad Pedal Power - help needed...
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Tonepad Pedal Power - help needed...
four_corners
Hey everyone.

I posted about this on diystompboxes (yet to hear from anyone there) but realized I've received some great advice and help here, so I thought I'd ask.

I decided to build a diy adjustable power supply today, called the Tonepad Pedal Power supply, and it (seemingly) went together well. Here is the build doc...

http://www.tonepad.com/getFile.asp?id=111

After plugging in the 12VAC power supply into the Tonepad Pedal Power and adjusting the trimpot, I was getting a solid 9V DC reading out the other side from my multimeter.

I plugged in my Zvex Box of Rock because it was sitting right there, and all seemed well. But, if I basically plugged in anything other than the measly 3 mA current draw of the Box of Rock, I get a crazy voltage drop, for example, down to 3-4 volts for a very simple delay pedal. What could cause a huge voltage drop like that?

Anyone have any ideas of what may be going on? The output on the 12VAC adapter says 1500mA, but I'm not sure what happens to it as it moves through the filtering and what not of the Pedal Power.

I am very much a novice in this department, so maybe I translated the schematic incorrectly, but I built this from a veroboard layout I drew up that I've attached. Sorry for such a messy layout if anyone decides to look at it! There aren't actually 2 separate grounds, I just connected them together and wrapped them around the nut on the DC jack that goes out to the pedals. I also didn't put in the 5 or so DC jacks like in the schematic, as they aren't isolated anyway, meaning I could just put one jack and use one of those chain power cables.

Any help would be greatly appreciated!

-Josh
Reckless_Experimenter
If you could post a picture of your build that would be most helpful in debugging.

Things to check:
That your diodes are in the correct orientation.
That the IC (LM317) is in the correct orientation.
For cold solder joints, a high impedance joint will definitely limit current output.
You might also needs a heat sink on the LM317, if it gets too hot it will go into thermal overload and drop the output. (If its too hot to touch, its too hot)

Good Luck!
four_corners
Reckless_Experimenter wrote:
If you could post a picture of your build that would be most helpful in debugging.

Things to check:
That your diodes are in the correct orientation.
That the IC (LM317) is in the correct orientation.
For cold solder joints, a high impedance joint will definitely limit current output.
You might also needs a heat sink on the LM317, if it gets too hot it will go into thermal overload and drop the output. (If its too hot to touch, its too hot)

Good Luck!


Thanks for all the suggestions. The LM317 didn't seem to get very hot at least from my preliminary tests, but I put a heat sink on it anyway just in case.

I'll check for cold solder joints.

I don't think I put the diodes or the IC in the wrong orientation, unless it looks wrong on my Veroboard layout. Did you happen to check out my Veroboard image that I attached to my first post?

Thanks again!
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