Moog schematics

[A.S.P.]

going back in time with the Search Butt On

[Paul Perry (Frostwave)]

Ray notes on his site that current needs are 20ma a side at +/-12v.  Not great for battery life, and pushing the capabilities of a charge pump.
You know what we need?  We need a little retrofit board for conversion of 9-12VAC to +/-9vdc or +/-12vdc.  Something you can stick inside a pedal and conveniently use an AC wallwart to get the requisite bipolar supply.  Choose your regulator value (9, 12, 15) from the 78L series (they all fit in the same space) and away you go.

Mark is right, (Ray's stuff is really for use with modular synths, that typically have +-15 or +-12 rails) but remember, the 78L series positive regulators and the 79L negative regulators have different pinouts. When I troubleshoot anything with a TO220 reg, I have to remember that the metal case of a 78 reg is ground - very handy - BUT, for the 79, the case is the - output!!!

[Wild Zebra]

 

You know what we need?  We need a little retrofit board for conversion of 9-12VAC to +/-9vdc or +/-12vdc.  Something you can stick inside a pedal and conveniently use an AC wallwart to get the requisite bipolar supply.  Choose your regulator value (9, 12, 15) from the 78L series (they all fit in the same space) and away you go.

Now I don't normally like to help out you stuck up stompbox dudes , but I like Ray so if it'll get some of y'all to turn that awesome phasor into stompbox form well, here you go.

http://modular.fonik.de/soundlab/sl_psu.pdf

hope this helps.

[Mark Hammer]

What a man!!  What a citizen!!!  Thanks brother zebra!

Just out of curiosity, because I don't have any means at my disposal to evaluate it at the moment, is that the sort of thing that can fit in a 1590BB lying on its side?

[Wild Zebra]

You know what Mark, I'm not sure.  I have not seen any completed builds.  But if you were to open it in acrobat that would be the actual size, cause I think it's ready for PNP.  Here is the topic at electro-music http://electro-music.com/forum/viewtopic.php?t=12968 It is a pretty swell circuit, could come in real handy.

Looks like maybe 4.25 by 1.50  Can't remember what size that hammond is.  All right lets see some synth based diy guitar pedals!

[Dan N]

http://modular.fonik.de/soundlab/sl_psu.pdf

Don't those regulators want to see 3 (or is it 2) volts above their output?

[Mark Hammer]

Right, they do.  The board accommodates 9v regulators seamlessly and they WILL work with the 12.73v you get when you rectify 9VAC.  Alternatively, you can just plug in a 12VAC wallwart without any changes to the board itself and get roughyly 17V rectified, which will do you for a +/-12VDC supply.  That's the beauty of AC - it gets turned into something else by the regulation and plug polarity is moot.  The working assumption with DC is that the wallwart voltage IS the voltage and that the pin and shankpolarities ARE the ones needed for power..

[slacker]

Doesn't the diode and cap arrangment make some sort of voltage multiplier? Which probably gets you enough DC for the 12 volt regulators.
Kind of like 2 of the second version on this page http://www.play-hookey.com/ac_theory/ps_v_multipliers.html

[Mark Hammer]

More or less.  The conversion factor is roughly 1.414.  Rectify 9VAC in the absence of a regulator and you get 12.726VDC.  The regulator wants at least 2VDC more at its input than at its output.  With a 9VAC wallwart, you could make use of essentially any 3-pin regulator at 10VDC or below.

Note that while the conversion yields 12.726VDC in this instance, that supply voltage is not particularly ripple free.  Depending on the cap size you've selected for the PSU board (stock shows 2200uf but that's a chunky cap) and the needs of the effect circuit itself, you MIGHT be able to get away without the regulators and just take the power from the non-ground side of C3 and C4.  Certainly makes for a smaller board, but you probably want to make 60hz drones a vital part of your music if you choose to go that route.

[slacker]

Right I've figured it out now.  I'd misundstood the term multiplier and thought it meant you'd get more than 12.7 volts per side, but then the penny dropped  It's basically full wave rectifying both "sides" of the AC to give you +12.7 DC and -12.7 DC. As oppsed to using a bridge rectifier to full wave rectify 9 volts AC into just +12.7 DC so thats where the term multipler comes from.

[Mark Hammer]

Bingo!