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'Power Supplies[OT]'
2000\05\05@181808 by Andrew Seddon

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<x-flowed>Can anybody recomend a battery/power supply circuit for the following
application. I really only need to supply some 5v logic so idealy i`d like a
5v battery. However space is very very limited so I would like to stick to
AAA size or smaller. I need to be able to draw a peak of 400mA for prehaps
20s, at normal times the draw will be about 100mA. Price is irelavent and it
does not need to be rechargeable, the more energy in it the better.

Thanks in advance for any help.

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</x-flowed>

2000\05\05@183915 by Josh Koffman

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Andrew Seddon wrote:
>
> Can anybody recomend a battery/power supply circuit for the following
> application. I really only need to supply some 5v logic so idealy i`d like a
> 5v battery. However space is very very limited so I would like to stick to
> AAA size or smaller. I need to be able to draw a peak of 400mA for prehaps
> 20s, at normal times the draw will be about 100mA. Price is irelavent and it
> does not need to be rechargeable, the more energy in it the better.

I know they are too large...but perhaps something like the Energizer
lithium batteries? They sell them in AA size, but perhaps someone makes
a smaller size? I don't know anything about their specs though. Maybe
you can find someone to build you a micro nuclear reactor. Then you'd
only have to change the batteries once every 87 years I think :) I'm
sure someone on here could whip one up in a weekend or two.

Have fun :)

Josh Koffman
spam_OUTjoshyTakeThisOuTspammb.sympatico.ca

2000\05\06@002504 by Wagner Lipnharski

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Hello Andrew, perhaps you could explain more about the available space
and how long do you need that 5V to supply 100mA after the 20s of peak
400mA.  TNR company here in Florida produce (and represent) several
different kinds of batteries and sizes, probably one could fit perfectly
to your application.  One more point... what is consumming 400mA for
20s? a relay? If yes, you could drop it down significativelly using
latching relays, since they consume only during the transfer from latch
to unlatch or vice-versa.
Wagner.

2000\05\06@024534 by Jon Hylands

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On Fri, 5 May 2000 15:16:25 PDT, Andrew Seddon <.....seddonaKILLspamspam@spam@HOTMAIL.COM> wrote:

> Can anybody recomend a battery/power supply circuit for the following
> application. I really only need to supply some 5v logic so idealy i`d like a
> 5v battery. However space is very very limited so I would like to stick to
> AAA size or smaller. I need to be able to draw a peak of 400mA for prehaps
> 20s, at normal times the draw will be about 100mA. Price is irelavent and it
> does not need to be rechargeable, the more energy in it the better.

http://data.energizer.com/datasheets/library/primary/lithium/l544.pdf

Stick a couple of those in parallel... That will give you 6 volts, 500 mA
continuous, in a 4/3N package, with 380 mAh capacity. Hard to beat
size-wise, and you can just keep adding batteries in parallel to increase
capacity.

Later,
Jon

--------------------------------------------------------------
  Jon Hylands      JonspamKILLspamhuv.com      http://www.huv.com/jon

 Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
          http://www.huv.com

2000\05\06@084835 by Andrew Seddon

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<x-flowed>Well idealy i`d like the whole battery to last for 3-4 hours, this would
include approx 10-15 20`s burts of 400mA. Unfortunately it is a large bank
of LED`s that is using the power that can`t be avoided. The lize limitation
is mainly how tall the battery is, it should be at most 15mm tall. And after
that as small as possible on every other axis. Like I said before cost is
not an issue as this is a one off, also I can replace batteries after every
run so they do not need to be re-charable. I am currently desiging the board
so I can work around the battery.

Thanks for any help.

>Hello Andrew, perhaps you could explain more about the available space
>and how long do you need that 5V to supply 100mA after the 20s of peak
>400mA.  TNR company here in Florida produce (and represent) several
>different kinds of batteries and sizes, probably one could fit perfectly
>to your application.  One more point... what is consumming 400mA for
>20s? a relay? If yes, you could drop it down significativelly using
>latching relays, since they consume only during the transfer from latch
>to unlatch or vice-versa.
>Wagner.

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

</x-flowed>

2000\05\06@113335 by Jon Hylands

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On Sat, 6 May 2000 05:46:43 PDT, Andrew Seddon <.....seddonaKILLspamspam.....HOTMAIL.COM> wrote:

> Well idealy i`d like the whole battery to last for 3-4 hours, this would
> include approx 10-15 20`s burts of 400mA. Unfortunately it is a large bank
> of LED`s that is using the power that can`t be avoided. The lize limitation
> is mainly how tall the battery is, it should be at most 15mm tall. And after
> that as small as possible on every other axis. Like I said before cost is
> not an issue as this is a one off, also I can replace batteries after every
> run so they do not need to be re-charable. I am currently desiging the board
> so I can work around the battery.

With 15 20-second bursts at 400 mAh, and 4 hours at 100 mA, you're using
about 440 mAh of capacity (yeah, I know, capacity varies with current draw,
but we're just doing simple approximations here). If you took three of the
batteries I mentioned in my previous post, you would have a 6 volt battery
with about 570 mAh total, in a package 13mm x 25mm x 39mm.

4 AAA alkalines will give you twice as much capacity, but you're looking at
a package 11mm x 44mm x 45mm...

Later,
Jon

--------------------------------------------------------------
  Jon Hylands      EraseMEJonspam_OUTspamTakeThisOuThuv.com      http://www.huv.com/jon

 Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
          http://www.huv.com

2000\05\07@013941 by Mark Willis

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Thought for you, Andrew;  By strobing the LED's at about 20Hz (IIRC -
see Archived posts about greater apparent brightness of strobed LED's)
you can (a) increase the perceived brightness of the LED's, and (b) save
some current (as averaged over time) compared to just straight running
the LED's via steady DC power.  (May want to use a larger resistor
during initial code tests, to prevent blowing the LED's if you're
turning the LED's on too long <G>)

Haven't done this yet - It's something I have been meaning to play with
(just bought a "scad" of LED's so am no longer waiting for LED's for
this.)  Haven't DONE it yet but certainly lots of posts on the list
about it.  Ought to be quite interesting with a large LED array.

 Mark

Andrew Seddon wrote:
{Quote hidden}

--
I re-ship for small US & overseas businesses, world-wide.
(For private individuals at cost; ask.)

2000\05\07@191902 by Russell McMahon

picon face
>Thought for you, Andrew;  By strobing the LED's at about 20Hz (IIRC -
>see Archived posts about greater apparent brightness of strobed LED's)
>you can (a) increase the perceived brightness of the LED's, and (b) save
>some current (as averaged over time) compared to just straight running
>the LED's via steady DC power.  (May want to use a larger resistor
>during initial code tests, to prevent blowing the LED's if you're
>turning the LED's on too long <G>)


Much higher than 20 Hz needed. maybe you meant 20 kHz.
At 20 Hz you would get bad flicker.
A minimum of 50 to 100 Hz is needed for flickerless operation.

Effective efficiency increases at much high pulse rates. Typically one hits
the LED with a short but very high current pulse - typically several amps
for a period of microseconds and a repetition rate of say 1 KHz. The MEAN
current can be lower than the previous DC current for the same brightness.
Many LEDs and displays are specifically characterised for operation in this
manner - peak permissible currents, duty cycles and repetition rates are
given.

Note- simple starting point

           uS's  x Amps  at 1 KHz = mA mean
(simply because powers of 10 cancel appropriately)

eg   10uS pulse at 2A at 1 Khz repetition rate = 20mA mean.


RM

2000\05\07@192744 by Mark Willis

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Russell McMahon wrote:
> Much higher than 20 Hz needed. maybe you meant 20 kHz.
> At 20 Hz you would get bad flicker.
> A minimum of 50 to 100 Hz is needed for flickerless operation.

I'd recalled it as 20Hz somehow.  Wrongly.  Obviously you've done it
<G>  I'll re-read the Archives before playing, as I said.

Having problems getting the LED array to fit in the durn case, right now
(Grrr.  LOOKS like it should fit, doesn't.)  "Try, Again", with
different LED's...

Thanks for the info patch, Russell, should help Andrew as well.

 Mark

2000\05\07@193353 by l.allen

picon face
> Effective efficiency increases at much high pulse rates. Typically one hits
> the LED with a short but very high current pulse - typically several amps
> for a period of microseconds and a repetition rate of say 1 KHz. The MEAN
> current can be lower than the previous DC current for the same brightness.
> Many LEDs and displays are specifically characterised for operation in this
> manner - peak permissible currents, duty cycles and repetition rates are
> given.
>
I made the dumb ass mistake of forgetting the fine print in
the technical manual for some high power (and high
priced) mosfets.

I exceeded the max peak current for a few microseconds
by 20%. 12 dead mosfets.
Took me a while to figure out what had happen since the
continuous current was no where near exceeded, the
voltage was o.k. and power dissipation was well within
spec.

Just a word from 'the been there done that stupid thing'
dept.
_____________________________

Lance Allen
Technical Officer
Uni of Auckland
Psych Dept
New Zealand

http://www.psych.auckland.ac.nz

_____________________________

2000\05\07@220620 by andy howard

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> From: "Mark Willis" <mwillisspamspam_OUTFOXINTERNET.NET>



> Having problems getting the LED array to fit in the durn case,
> right now (Grrr.  LOOKS like it should fit, doesn't.)
> "Try, Again", with different LED's...


Try again with BIGGER HAMMER...














.

2000\05\08@061750 by Arthur

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face
why so heavy use a tyre lever or for our American cousins tire lever.
regards Art :-)

----- Original Message -----
From: andy howard <@spam@musicaKILLspamspamUKONLINE.CO.UK>
To: <KILLspamPICLISTKILLspamspamMITVMA.MIT.EDU>
Sent: Monday, May 08, 2000 3:04 AM
Subject: Re: Power Supplies[OT]


: > From: "Mark Willis" <RemoveMEmwillisTakeThisOuTspamFOXINTERNET.NET>
:
:
:
: > Having problems getting the LED array to fit in the durn case,
: > right now (Grrr.  LOOKS like it should fit, doesn't.)
: > "Try, Again", with different LED's...
:
:
: Try again with BIGGER HAMMER...
:
:
:
:
:
:
:
:
:
:
:
:
:
:
: .

2000\05\08@105845 by Andrew Seddon

picon face
Seem`s interesting. I wonder if it would work in my application. The LED`s
in question are part of an image sensor module. I presume it wouldn`t as it
is only apparent brightness that is increased, I`ll give it a try tho and
see what happens.

{Quote hidden}

bank
> > of LED`s that is using the power that can`t be avoided. The lize
limitation
> > is mainly how tall the battery is, it should be at most 15mm tall. And
after
> > that as small as possible on every other axis. Like I said before cost
is
> > not an issue as this is a one off, also I can replace batteries after
every
> > run so they do not need to be re-charable. I am currently desiging the
board
> > so I can work around the battery.
> >
> > Thanks for any help.
> >
> > >Hello Andrew, perhaps you could explain more about the available space
> > >and how long do you need that 5V to supply 100mA after the 20s of peak
> > >400mA.  TNR company here in Florida produce (and represent) several
> > >different kinds of batteries and sizes, probably one could fit
perfectly
{Quote hidden}

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