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RE: power supplies

Doug,
I was just thinking, there's no problem with soldering banana clips on
Lithium Ion (Sony NP-F960) and banana clips on the charger right?  I can't
find banana clips that would fit correctly in the holes within the Sony
batteries.  I've been using a make shift connector and it's not reliable.
Will soldering the battery and charger pins damage anything (other than make
it unusable for regular batteries?

Zach

-----Original Message-----
From: Doug Sutherland [mailto:]
Sent: Friday, June 08, 2001 12:41 PM
To: Russell Kohn; Wear-hard List
Subject: Re: power supplies

Russell Kohn wrote:

> OK, I recently came into some money (although the sad part is that for me
> that means <$500) so I'm looking really seriously at the PCM-5822. My one
> concern has been about power supply (well, to say my "one" concern is
> misleading... so we'll say the concern that has popped into my head at
> this insanely early hour of the morning). Will I really need to spend $170
> on a DC power supply?

No. If you're willing to do some soldering, here's an affordable way to
power that PCM-5822:

1) Get some of these toshiba PA2487U laptop batteries and a PA2488U charger
   for them on ebay:

http://search.ebay.com/search/search.dll?MfcISAPICommand=GetResult&ht=1&Sort
Property=MetaEndSort&query=PA2487U
http://search.ebay.com/search/search.dll?MfcISAPICommand=GetResult&SortPrope
rty=MetaEndSort&pb=&ebaytag1=ebayreg&ht=1&st=2&query=PA2488U

2) Get some mini banana plugs and jacks and stranded wire for connection
   of batteries to regulator and regulator to CPU

3) Get one of these PT6302A regulators (5V 3A) from Digikey
   http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=228&M=PT6302A

4) You need one 100uF capacitor for the regulator, you can get it at Digikey
   or at radio shack.

5) Get a 12V 3A AC/DC adapter for powering from AC.

6) Get a cigarette lighter adapter cord for powering from vehicle.

7) The only other thing you need is stranded wire and one 100uF capacitor.

Total estimated cost of power solution:

  4 PA2487U 10.8V 3600mah li-ion battery packs     $120.00
  1 PA2488U battery charger                         $40.00
  1 PT6302A regulator                               $25.00
  1 100uF Capacitor                                  $2.00
  6 mini banana sockets female                      $10.00
  1 mini banana plug male                            $2.00
  1 roll 20-22 AWG stranded wire                     $3.00
  1 120/220VAC to 12VDC 3A AC/DC adapter            $20.00
  1 auto cigarette lighter power cord                $5.00
                                                   -------
                                                   $227.00

This configuration gives you approx 155 battery watt hours,
ability to plug into AC and vehicle power, plus all of your
charging and regulation for $227, and the power regulator is
tiny, smaller than your thumb. Set it up like this:

  - Carefully solder stranded wire onto the positive and
    negative battery terminals, and put female banana plugs
    on the end of each wire. Note: I have always done this
    in reverse, with the male banana plug on power sources
    and the female socket on wearable, but it makes sense
    to do it the other way around (female on power source)
    because the female sockets won't touch metal items and
    short out the pack in transit. If you want to run more
    than one battery pack in parallel, you can put an extra
    banana junction on each battery pack wire so they can
    be chained together (pos-to-pos and neg-to-neg):

                     |------ banana plug to next battery
    terminal --------|
                     |------ banana jack to regulator

  - Cut off the end of the AC/DC adapter and cigarette
    lighter cord and put the same banana sockets on them.

  - Put male banana plugs on the regulator. The PT6302A is
    easy to hook up. There are only power input, ground,
    and power output pins. Attach the banana plugs to the
    power input and ground, and attach the power output
    and ground to the PCM-5822. You need to add the 100uF
    capacitor per the PT6302 data sheet "typical application"

http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=PT6302
    http://www-s.ti.com/sc/psheets/slts031b/slts031b.pdf

The above doesn't give you onboard charging or monitoring, but
it does give you lots of power for a reasonable price, regulator
is very small, and its easy to charge and swap batteries or
switch over to AC or DC vehicle power.

> what are the outputs of normal power supplies?

Power supplies exist in zillions of configurations. For wearables
you probably want 5 volt single output non-isolated rated for
about 3 amps.

> What I mean by that question is: will I be able to run my hard
> drive (which needs twelve as well as five volts) off the same
> power supply?

I don't think your hard drive needs 12 volts. If it does, its time
to grab a new hard drive. You can get a 20GB laptop drive for $112.

> and lastly, how big are these power supplies and how much heat do
> they generate?

The Powertrends ISRs (integrated switching reglators) and the Datel
DC/DC converters are tiny single chip solutions. There are lots of
big 4x4 inch or larger supplies out there (ie Tri-M and Parvus etc)
but I wouldn't use one of those unless it gave me charging and
monitoring capabilities (you have probably seen by now that these
features are not easy to implement on wearable).

  -- Doug

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