[sdiy] power supplies

[gregory zifcak]

thanks for all the help everyone! i'll try to get it assembled this weekend.

greg


>From: Colin Hinz <asfi at eol.ca>
>To: <synth-diy at dropmix.xs4all.nl>
>Subject: Re: [sdiy] power supplies
>Date: Thu, 26 Feb 2004 01:14:11 -0500 (Eastern Standard Time)
>
>On Wed, 25 Feb 2004, gregory zifcak wrote:
>
> > i found this one, which apparently takes 16 or 12vac:
> > http://sound.westhost.com/project05.htm
> > would starting with 18vac give me higher output amperage? i'm not sure 
>what
> > my circuit needs. if i use 18vac, should i still use the 7815 and 7915? 
>are
> > there any other components that would have to be changed?
>
>The main things to be concerned about are:
>
>1) The electrolytic capacitors may need to be a higher voltage rating.
>I would use 35V parts to be on the safe side. Looks like there's
>ample room on the board for the higher-voltage parts. Go with even
>larger electrolytics on the input side, if you can -- the AC is
>merely half-rectified so you'll get *much* more ripple in the DC
>which goes into the regulators.
>
>2) If you're using a lot of current (hundreds of milliamps), you
>may need beefier heatsinks. You need two separate heatsinks as the
>heat conductive tabs will be at different voltages.
>
>I've used this type of circuit with great success, though hand-wired
>with solder lugs -- but having a nice PCB makes the construction
>so much easier.
>
>I disagree with the use of a 3-pin XLR connector for the power input,
>though. One day, someone will pick up the power cable and plug it
>into a microphone by mistake......*bzzzzt*. Reminds me of the
>(apocryphal?) story of the guy who used regular two-prong mains
>plugs to connect his speakers to his home-built amplifier. This
>scheme worked well until someone unaccustomed to his wiring
>scheme plugged the speaker cables into the house mains. I wonder
>how far the cone moved before the coil melted......:=(
>
>- Colin Hinz
>   Toronto, Canada
>
>
>

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