DIY Power Supply Question

Frequently asked questions regarding powering your pedal.
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Dr Tony Balls
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Post by Dr Tony Balls »

I've built a few power supplies using this type of general schematic: http://topopiccione.atspace.com/pjimage ... sa.sch.gif

Basically i'll use a scavenged 12VDC wall-wart, and run it through 4 or 5 branches like in the schematic with filtering and a 9V regulator in each branch, and then output to 2.1mm barrel jacks from there. This works totally fine but the build is a pain in the ass because I wind up having to build all the 2.1mm to 2.1mm power cables to use the thing. I thought about buying the cables on line, but they're hard to find for cheap. Daisy-chain power cables, on the other hand, ARE available and cheap. So it got me thinking....

What is the real benefit of having separate filtering and regulation on each branch? Is there one, or is just done that way to accommodate the current limits of the individual regulators? This regulator is good to 1.5A, so couldnt you build a simpler power supply with one regulator like this and use the one channel for multiple effects? What are the drawbacks of that (other than potentially needing a heatsink)?

http://www.mouser.com/ProductDetail/STM ... NDZyHx8%3d

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Dr Tony Balls
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Post by Dr Tony Balls »

Anyone have any input about this?

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nzCdog
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Post by nzCdog »

I think the medusa is a bit overkill for what it can provide tbh. (Not having tried it, it may be fine) Lots of extra filtering is nice, but every pedal will have additional filter caps onboard anyway, and having several identical regulators seems a little redundant when one regulator could do the same job up to its max current o/p. From what I can see, it's all on the same ground circuit so in theory still susceptible to that ground hum. :(

On my pedalboard I daisy chain 9x 9v effects, mix of purchased and DIY, all from ONE quality wallwart PSU (Boss PS100)
One fuzz pedal goes through a 7660 to invert the output to -9V and one pedal takes +9 and charge pumps it to +17V
But even with those two oddballs it runs very quiet.

However... I'm currently building my own power supply. Not really because I need to right now, I just want it better and I have some future ideas. :)
It's based on the Spyder by RG... Check out that article for some insight into PSUs. I bought a nice R-Core Tranny (very efficient/very quiet) with 4 secondaries, and I'm using 4 LM317s with 'the works' as prescribed by their datasheet for filtering etc. Theyre all tweakable outputs, but at this stage I'm gonna do 2x isolated 9Vs, 1x isolated 12V and 1x isolated 12.6 V... (for a tube pedalproject) on pcb, metal housing, good lead dress, EMI filtered socket etc... and I plan to daisy chain the pedals still where required... So I just hope after all the effort it ends up at least a little better than what I have now :roll: :lol:
Shaken, not stirred... Christchurch, New Zealand.

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