Re: [Kinda OT] Power Supply

[julian814@hotmail.com (Ralph Glatt)]

carbide@egine.com (Paul G.) wrote in message news:<88ad692d.0408181352.4e318ae2@posting.google.com>...
> julian814@hotmail.com (Ralph Glatt) wrote in message news:<ce9c44dd.0408170659.516c726b@posting.google.com>...
> > I have a question about a power supply for a ZX81, but no one on
> > comp.sys.sinclair seems to be willing to help me, but since it's a
> > general question and not system specific, I thought I might get an
> > answer here.
> > 
> > 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?
> > 
> 
> 9V DC adapters are very common, a lot of answering machines use 'em.
> Of course, they don't use the same type of connector so you'll have to
> wire one on.
> 
> I just looked at a Timex Sinclaire 1000, which I think is the same as
> a ZX81. The AC adapter says 9.75V DC, 650ma. I checked with a DMM- the
> tip is positive.
> 
> I seem to recall opening up a ZX81- I believe it has an internal
> regulator, probably to regulate the 9V to 5V.

Yeah, the only real differences between the Timex and the ZX81 are
some of the keys and the Timex has an extra 1k of RAM. Like I said, I
managed to find a 9v DC 1 amp power supply at Goodwill, but it needs a
new jack on the end. I think I can handle that. ;-) The extra mA will
help when I find a printer for it, because they use up the extra. The
real trick will be in making the cable needed to download the software
from the net and onto cassettes that I can use with the ZX81!


Ralph Glatt