RE: Power supply with AC voltage?

[goddard.duncan@mtvne.com]

Title: RE: Power supply with AC voltage?

>>I may reveal my ignorance here but I assume you can't
use DC voltage when AC is required, is this correct?<<

nearly everything I've seen that claims to need AC will subsequently rectify this to dc and regulate it internally. one notable exception is the alesis mmt8.... this does two different things with the 9V ac; there's the usual 5V regulator but it also has a higher rail derived from the 9V that I didn't get to the bottom of. I now run it off a small 9V toroidal that's fitted inside an alesis synth module; this transformer has a split-primary in oredr to run off 110V or 220V.

 
if you think about, the ac input thing is just a way for the manufacturer to avoid having to produce two flavours of box for 110V and 220V use, or fit a switch in a split-primary that some user will one day forget to adjust correctly and possibly fry some delicate electronics because, let's face it, fuses are just not fast enough to prevent some smoke getting out. and as we know, smoke is what makes stuff work. let the smoke out of anything and it's broken....

the reverse is not the case, though. if it says it wants dc, dc is all that will work, and it has to be the right way up. lots of gear is fitted with a simple diode to protect against polarity reversal, but you could damage the power supply itself.

all my wall-wart stuff (including things like effects units and, yes, a GI-10) now runs from a laptop supply that kicks out about 2 amps or so at 15V. the particular model I use also has 5V and -15V outputs so I can run a real mixture of stuff. obviously, this puts me in custom-rig land, and you'd really have to be confident with soldering and so forth to emulate this set-up. the other benefits of the laptop psu are that it's quite small and doesn't buzz or get hot, and it runs off anything between 80V and 300V the outputs are so smooth that I can distribute them over the spare wires in my midi cables. this works fine and I have gigged with this set-up several times with no glitches.

d/r.m.i.

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