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Here's a post of mine from back in Dec'97.
GB
----- Original Message -----
From: Graham Baker <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, 24 December 1997 12:01
Subject: Re: MD: Sharp 701 power Supplies
> More questions and thoughts regarding the 701/702 and power supplies.
>
> Page 55 of the manual lists the supply volts required from various
sources:
>
> 3.6V - lithium battery
> 3V - 2 x AA batteries
> 4.5V - car adapter
> 5V - mains adapter
>
> Now, how can the 701 determine the difference between 4.5V from a car
> adapter and the 4.5V coming from a mains adapter?!!
> IMHO, 4.5V should power the 701 OK. It seems to work fine with my Tandy
(RS)
> Mains adapter, BUT the actual measured voltage varies around 5.02V
whilst
> under load (701 playing)
> This adapter is a multi-voltage device with a switch to select from 3V
to
> 12V in 1.5V steps. It is unregulated and rated at only 500ma.
> I guess it supplies the required current (around 800ma) at 4.5V (5.02V)
> because it's rated 500ma would be at 12V, and it is capable of more
current
> at 4.5V.
> This would explain why an adapter of similar output current (400/500ma)
but
> only a *fixed output* of 4.5V could go up in smoke, as someone reported.
> The only reason I can see for a 0.5V difference between the car and the
> mains adapter would be to prevent the li-ion batt from charging from a
car
> battery, to limit the current being drawn. Can anybody confirm that a
701
> used from a 4.5V car adapter will not recharge the battery?
> If this is the case, maybe regulated adapters that give an exact 4.5V
will
> actually cause the 701 to think it is being powered from a car adapter
and
> that the 4.5V will not allow the li-ion batt to recharge, as was
reported
> recently.
>
> I hope all this hasn't further confused the issue!!
> Any comments/thoughts welcome.
>
> Graham Baker
>
>
>
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