Re: [Kinda OT] Power Supply

[julian814@hotmail.com (Ralph Glatt)]

salfter@salfter.diespammersdie.dyndns.org (Scott Alfter) wrote in message news:<lgrUc.24109$Yl.7836@okepread07>...
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> In article <ce9c44dd.0408170659.516c726b@posting.google.com>,
> Ralph Glatt <julian814@hotmail.com> wrote:
> >The ZX81 takes a power supply that puts out 9v DC around 800 mA. I
> >needed one, and a friend gave me a 9v AC power supply and said use
> >that. Thing is, I'm afraid if I use the wrong kind of voltage, I might
> >fry the board, which I don't want to do, because the ZX81 isn't all
> >that easy to get in the US. Should I try it, or should I keep looking
> >for a DC power supply?
> 
> Given the minimalist nature of the ZX81's design, feeding it AC when it
> wants DC would probably toast it.  It'd be easy enough to lash up a bridge
> rectifier, filter capacitor, and linear regulator to get regulated 9V DC for
> your computer.  I think you can even still find all the parts at Radio
> Shack.  For the rectifier, pick something that can handle around 1-1.5A. 
> You could also use a diode instead of a bridge rectifier, but it won't be as
> efficient.  For the capacitor, I'd pick 470 or 1000 uF at at least 25V.  For
> the regulator, use an LM7809 in a TO-220 case; they're good for 1A.  You
> might also want to bolt a heatsink to the regulator, as it'll get toasty
> without it.

Thanks, Scott, but I think I found a way that's a little easier.
Goodwill had a 9v DC power supply , but with the wrong jack at the
end. I managed to get the right one at Radio Shlock, so all I have to
do now is some cutting and splicing. I think I can handle that. ;-)


Ralph Glatt