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Subject: Re: FM Recorder won't turn on / USB left connected overnight
From: Neon John (johngd_at_bellsouth.net)
Date: 2003-10-21


On Tue, 21 Oct 2003 11:17:12 +0200, "Arturo Gonzalez" <agon_at_email.arizona.edu>
wrote:

>I was under the impression that the batteris on the Recorder couldn't be
>removed. Is it as easy as unscrewing the 4 screws around the blue
>cushions?

All the recorders that I've been involved with have a battery door on the top
that can be opened by gently twisting a screwdriver in that square hole and
then pulling the lid toward the front of the unit. The bottom of the unit has
a lid that is held on with 2 screws but I've never removed it and don't know
what is under it.

The battery is simply a square cube that slides out. Here is a photo:

http://bellsouthpwp.net/j/o/johngd/files/misc/FM_battery.jpg

The battery is actually two cells running in parallel.

>
>When you say "limited power supply" what exactly did you use? I am away
>from all of my tools living abroad, and have limited electrical
>knowledge/experience, and so I'm a little lost and need a little bit
>more specifics...

I am referring to a power supply that can have its current limit adjusted in
addition to its voltage. Usually a bench-type supply. If you don't have one
handy then a 1 amp wall wart of any convenient voltage >6 volts will work.
Simply size a series resistor to limit the charge current to < about an amp.
The actual amount does not matter as long as the wart isn't overloaded, as
most of them have one-time fuses built in.

All the fancy charge management necessary for LiIon batteries only comes into
play at greater than about half charge. Up to half charged or perhaps a bit
more, the charge regime is a simple constant current (or maybe even
unregulated) charge. That is why we can get away with a "dumb" charge. Just
don't try to put more than about half the charge back using this technique. I
recommend a timer on the power supply to turn it off automatically. I use the
alarm function in my PDA to remind me as a backup. The battery can easily be
destroyed if too much charge is forced into it.

John

---
John De Armond
johngdDONTYOUDARE_at_bellsouth.net
http://bellsouthpwp.net/j/o/johngd/
Cleveland, Occupied TN



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