Here's the original post of Renard's that fixes the Sharp charging
problems.
GB
----- Original Message -----
From: Renard A. Dellafave <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, 23 December 1997 8:23
Subject: Re: MD: Sharp 701 recharge problems (how to build 5V supply)
> >A 6V 800mA unit will work if a current limiting resistor is inserted
> >in the hot lead.
>
> OK, if you're going to go to THIS much trouble do it right and buy a
7805
> regulator. Power to the left pin, 5V out on the right pin, and ground
for
> both in the middle. Handles up to an ampere with a heatsink (not much
> without).
> Better run at least 7V in to be safe, it has a pretty high dropout
(i.e.,
> amount the input needs to exceed the output voltage) as regulators go,
but
> it's cheap, reliable, and puts out an honest-to-goodness five volts.
> Available at Radio Shack, or ANY electronic parts supplier (this is a
VERY
> COMMON part). Ideally you might throw a 100uF capacitor on the input
and a
> few hundred on the output but they work fine without that.
>
> You can buy a metal project box at RS too and use that as the heatsink,
get
> a couple grommets...easy project if you have any soldering skills at
all.
>
> BTW, the input adaptor needs to be able to supply the full 800mA (or
> whatever the portable needs) current. Input voltage is not that
important.
> Anything from 7V DC on up to, oh, I wouldn't go over 12 V in, would be
> fine. The reg can handle 30V in I think, but remember that all the
> overvoltage (times current) gets turned into HEAT.
>
> e.g. with 12V in, 5V out, at 1 ampere it'll dissipate 7 Watts. I think
> that's within spec for a good heatsink...with 7V in it would only
dissipate
> 2 Watts.
>
>
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