Building A Re-Chargeable DC Power Supply?

Discussion in 'Burnt Fingers DIY Effects' started by The Ballzz, Sep 2, 2019.

  1. The Ballzz

    The Ballzz Tele-Afflicted

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    Hey Folks,

    Someone a while back posted about designing/building a rechargeable, battery based power supply for a modest pedal board. I believe he started with a single 12-volt battery and a buck converter. I can't find him or the thread, but I think I'd like to expand on his ideas anyway. I already have a BoxKing:

    https://www.amazon.com/gp/product/B074FWK46G/?tag=tdpri-20

    that works "pretty well" and it is quite liberating not having to run a power cable out to the pedal board. It does however, exhibit a few anomalies that I would like to design around. The whole concept is brilliant, I'm simply looking to make some improvements to the implementation!

    Here's a short list of what I'd like to address. Please bear in mind that while I'm not an electronics engineer, I'm a mildly skilled craftsman, with a well equipped shop and pretty OK soldering and fabrication skills.

    A) I'd like to have at least one or a couple of 9-volt outputs that are well isolated from the others. I'm not sure how to implement such isolation. Most of the outputs can be fairly happy in parallel.
    B) At least one 18-volt tap would be good.
    C) Having at least one isolated tap be adjustable from say, 7-volts to 9-volts would be important for my true bypass, beefed up wah that can get a bit noisy at 9+ volts.​
    I'm kinda hoping that someone here might help me understand the isolation design and how to best regulate and engineer such a unit?

    Thanks Folks,
    Gene
     
  2. dogmeat

    dogmeat Tele-Afflicted

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    to get 18 volts you need an 18V battery (or higher). you can make your own by putting cells in series, maybe re-purpose a cordless drill pack. from there all you need to do is wire up an LM7809 regulator chip for 9 volts, 7812 for 12 volts, etc. you could get 2 each 12v emergency lighting batteries (which are cheap) wired in series and have a LM7018 tap as well. LM 105 is variable... thats a number I remember but there are other choices. the LMs are about the size of your thumbnail & cost a buck and a half at Mouser. they can carry about 1.5A & have over current protection built in
     
    Last edited: Sep 2, 2019
  3. boop

    boop Tele-Meister

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    You can use a boost converter which are quite efficient ( >90%). You can buy cheap units for a few bucks. These trade off current to deliver a higher voltage. Here is a cheap unit which you can find on ebay and the like: https://www.addicore.com/MT3608-Boost-Converter-p/ad300.htm

    I would check specs and operate it conservatively for your needs. I'm not sure how much noise would be on the line using a cheapo one, but you could add more filtering to clean things up, or just shop around for something higher quality/more expensive.
     
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