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Power supply

Started by JRM, September 14, 2010, 08:43:20 AM

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JRM

What do you think of this as a power supply to a pedalboard with 7 pedals (Fuzz Face, Wah, Big Muff, CS Powerboost, DynaComp, Phase 90, Electric Mistress):
http://www.banzaimusic.com/HN-Power-HNP18-090.html
If I got too much noise I can always make a filtering section at the power input of the board.

petemoore

What do you think of this as a power supply
  It looks like it'll provide 1 floating, regulated output, as long as the current is sufficient for the device[s, appears fine.
to a pedalboard with 7 pedals (Fuzz Face, Wah, Big Muff, CS Powerboost, DynaComp, Phase 90, Electric Mistress):http://www.banzaimusic.com/HN-Power-HNP18-090.html
  ...assuming the Fuzzface is NPN, it should work [if the current rating abides], and will may allow noise introduction because of ground loops, depending on how strong the external noise signals are where the ground loops are allowed.
  See "Spyder" at GEO, for definition of problem, and solution = breaks all ground loops by lifting the supply grounds, floating outputs then ride on the signal ground.
If I got too much noise I can always make a filtering section at the power input of the board.
  Check the schematics of your units, many already have this 'always not a bad thing, often helps' filtering capacitor or R/C, if not it's only ~a 1 cap price and generally an easy finding of 2 correct points to solder, to install one, I considered it a basic good idea to have them there, ie it's easier to just have them than it is to try to figure out when they're needed.
Convention creates following, following creates convention.

JRM

Thanks a lot petemoore!
The ground/noise problems are addressable. At least I know that I have a hint how to handle with them or where to find solutions.
The Fuzz Face will be an npn si version (BC209B trannies), so no trouble for that.
The main problem is that I don't know how to calculate the current draw from each circuit! So I've just picked up the highest current adapter available from the list... :icon_redface:

slacker

The current draw of all those pedals is probably only a couple of hundred milliamps at most, probably less. Any of those power supplies should work fine, but given the small difference in price you might as well buy the biggest one, you can't really have too much power :)

JRM

Thank you very much slacker.
From the ones I remember only Boss states the current draw of its pedals and the ones I've checked run under 70mA. I'll be quite safe with a 2A power supply. Then I'll have to solve the other problems. One thing that I haven't explained is that they'll all have just one feed and will be permanently connected in series board to board (no patch cables) just separated by the 3PDT switches to enable true by pass any effect individualy. It's a kind of customized ME-70 or GT-10...

ianmgull

Forgive me if you already planned for this but the tip is positive; this is not the standard.

petemoore

Quote from: ianmgull on September 14, 2010, 09:14:00 PM
Forgive me if you already planned for this but the tip is positive; this is not the standard.
Barrel positive requires insulated DC Jack, maybe there's an easier way, but I just made the bodies grounded/connecting to the barrel of the DC jack, and the nut that tightens it, and made sure I got the polarity right for the input, reverse diodes are handy, a very quick power up and switch once has resulted in no-indicator-no-damage, not that I'd recommend it if it can be helped [not a bad practice, using indicator, and testing quickly even after otherwise making sure it's polarized correctly], it seems to have paid off because I then just reversed polarity to correct it. I found it easy to reverse polarize a couple times, and was glad I had that diode in there, one time the diode wasn't in there and it wasn't any fun.
Convention creates following, following creates convention.

JRM

Thanks folks. I was planning to buy an isulated DC jack anyhow. I don't know yet if I'll have an aluminium or wood enclosure (Al will look better but wood I can do it at home). I might add an on LED. Polarity will not be a problem: it's only one jack! I'll just have to triple-check all the polarities of all the 7 individual boards and it's connection to the dc jack.