Making Camera Power Supply from ATX PS

[Nehmo Sergheyev]

I have a HP M22 camera http://snipurl.com/fd13 , and here are its power
specs:

"Typical power usage: 1.35 Watts with Image Display on. 2.9 Watts
maximum power usage.
Power sources include the following:
.. Either two non-rechargeable AA Lithium batteries (included) or two
rechargeable AA NiMH batteries (purchased separately). Rechargeable
batteries can be recharged either in the camera using the optional HP AC
power adapter or optional HP Photosmart M-series dock, or separately in
the optional HP Photosmart Quick Recharger.
.. Optional HP AC power adapter (3.3 Vdc, 2500 mA, 8.25 W).
.. Optional HP Photosmart M-series dock.
Recharging in camera with the optional HP AC power adapter or optional
HP Photosmart M-series dock: 100% in 15 hours."

HP sells a $50 external power supply for the camera:
HP Photosmart 3.3V AC adapter C8912B http://snipurl.com/fd11 , which
provides 3.3 Volts.

A marking on the camera assigns the + polarity to the center connector
of the jack, and it's a small jack.

Q1: What do you call that kind of jack?

Q2: Computer ATX power supplies have a 3.3 V line. I have some old
unused power supplies (and I can buy them nearby for $5). Can I use an
ATX power supply to power the camera?

My understanding of an ATX is that normally one of the 5 V wires is
always on but the rest of the lines are controlled by a soft switch fed
to one of the wires.

Q3: What do I do exactly to turn on the power supply? Do I ground pin
14? (http://www.pavouk.comp.cz/hw/en_atxps.html pin out diagram scroll
down)

Q4: Will this camera, or camera's that require 3.3 V in general , work
on the 3 V (setting of the) power supplies like Wal-Mart sells
http://snipurl.com/fd4t?

Q5: I see some universal adapters
http://www.clubmac.com/clubmac/shop/detail~dpno~339148.asp " Equipped
with technology to calculate your camera's voltage " How does it
determine the camera's voltage requirements?

 

[philo]

I have a HP M22 camera http://snipurl.com/fd13 , and here are its power
specs:

"Typical power usage: 1.35 Watts with Image Display on. 2.9 Watts
maximum power usage.
Power sources include the following:
. Either two non-rechargeable AA Lithium batteries (included) or two
rechargeable AA NiMH batteries (purchased separately). Rechargeable
batteries can be recharged either in the camera using the optional HP AC
power adapter or optional HP Photosmart M-series dock, or separately in
the optional HP Photosmart Quick Recharger.
. Optional HP AC power adapter (3.3 Vdc, 2500 mA, 8.25 W).
. Optional HP Photosmart M-series dock.
Recharging in camera with the optional HP AC power adapter or optional
HP Photosmart M-series dock: 100% in 15 hours."

HP sells a $50 external power supply for the camera:
HP Photosmart 3.3V AC adapter C8912B http://snipurl.com/fd11 , which
provides 3.3 Volts.

<snip>
although in theory you could use the 3.3v connection of an atx
supply...i don't think it would be worth trying to do so...
as if you made a mistake you could damage your expensive camera...

$50 for that adaptor is of course absurd...
you could prob. find something at radio shack that would work...
however...why not play it safe and simply remove the batteries from the
camera and purchase a seperate charger.

it would certainly be the cheapest and safest thing to do

 

[kony]

I have a HP M22 camera http://snipurl.com/fd13 , and here are its power
specs:

"Typical power usage: 1.35 Watts with Image Display on. 2.9 Watts
maximum power usage.
Power sources include the following:
. Either two non-rechargeable AA Lithium batteries (included) or two
rechargeable AA NiMH batteries (purchased separately). Rechargeable
batteries can be recharged either in the camera using the optional HP AC
power adapter or optional HP Photosmart M-series dock, or separately in
the optional HP Photosmart Quick Recharger.
. Optional HP AC power adapter (3.3 Vdc, 2500 mA, 8.25 W).
. Optional HP Photosmart M-series dock.
Recharging in camera with the optional HP AC power adapter or optional
HP Photosmart M-series dock: 100% in 15 hours."

HP sells a $50 external power supply for the camera:
HP Photosmart 3.3V AC adapter C8912B http://snipurl.com/fd11 , which
provides 3.3 Volts.

They overprice it just a wee bit.

A marking on the camera assigns the + polarity to the center connector
of the jack, and it's a small jack.

"Tis the far more common arrangement but it's good that they
marked it.

Q1: What do you call that kind of jack?

Hard to tell from a picture but looks like a typical power
brick barrel, coax plug. Main thing is knowing the external
and internal dimensions in millimeters, and the tiny ones
are harder to measure, and find.

Q2: Computer ATX power supplies have a 3.3 V line. I have some old
unused power supplies (and I can buy them nearby for $5). Can I use an
ATX power supply to power the camera?

It'd be awefully bulky, but it's likely you can. However,
you should put a certain minimum load on the 5V rail to
stabilize the output. A 2 Ohm 10W power resistor should be
sufficient, connected between the 5V rail and ground- either
on one of the leads or inside the PSU if you feel competent
inside a power supply to figure that out- if not I'm not
going to tell you how to do it, but it isn't hard, just
fiddly taking the thing apart to do it.

My understanding of an ATX is that normally one of the 5 V wires is
always on but the rest of the lines are controlled by a soft switch fed
to one of the wires.

Yes 5VSB is always on, as is the PS-On line. You can ignore
the 5VSB and simply short the PS-On to a ground. If you
were opening up the power supply anyway to add the resistor,
I'd suggest drilling a hole in the casing and installing a
switch to short the two wires, turn it on/off.

Q3: What do I do exactly to turn on the power supply? Do I ground pin
14? (http://www.pavouk.comp.cz/hw/en_atxps.html pin out diagram scroll
down)

yes, it's pin 14, usually a green wire.

http://69.36.189.159/usr_1034/atx_on.gif

Q4: Will this camera, or camera's that require 3.3 V in general , work
on the 3 V (setting of the) power supplies like Wal-Mart sells
http://snipurl.com/fd4t?

I don't know.
The camera may have polarity protection, meaning you may
easily need slightly more than 3.0V to get a pair of
batteries charged fully.

The other issue is the current capacity of the supply, the
one you linked doesn't appear to have that listed.

Since the HP supply is spec'd as 2.5 amps, that would be the
general target... the camera might still work on less, maybe
1.5A, but then there's the issue of what the supply does if
it drops below any particular threshold voltage. I'd not
risk a camera with a less than 2A supply, myself.

Q5: I see some universal adapters
http://www.clubmac.com/clubmac/shop/detail~dpno~339148.asp " Equipped
with technology to calculate your camera's voltage " How does it
determine the camera's voltage requirements?

I don't know but I'd go ahead and get one spec'd for 3.3V
instead. Here's one, but you'd need come up with your own
plug for it,

http://www.allelectronics.com/cgi-bin/category.cgi?category=480&item=PS-334&type=store

Maybe this'd be helpful,
http://www.allelectronics.com/cgi-bin/category.cgi?category=123&item=PLG-6&type=store
but getting good measurements from the jack first would be
best.

Seems like I used to have an old electric shaver and a
microcassette recorder that both used similarly small
connectors, if you have such spare junk lying around it
might provide a part or aid in measurements.

 

[CWatters]

I have a HP M22 camera http://snipurl.com/fd13 , and here are its power
specs:

"Typical power usage: 1.35 Watts with Image Display on. 2.9 Watts
maximum power usage.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=50486&item=7521230305&rd=1&ssPageName=WDVW

 

[Kevin McMurtrie]

Just buy a regulated universal adaptor at Radio Shack or whatever your
local crapy electronics store is. It will cost about $30 and will work
with a lot more than your camera.

Switching power supplies can get twitchy outside of a their normal load
range. I wouldn't connect one to my camera without doing some stability
tests first.

 

[Shep©]

although in theory you could use the 3.3v connection of an atx
supply...i don't think it would be worth trying to do so...
as if you made a mistake you could damage your expensive camera...

$50 for that adaptor is of course absurd...
you could prob. find something at radio shack that would work...
however...why not play it safe and simply remove the batteries from the
camera and purchase a seperate charger.

it would certainly be the cheapest and safest thing to do

Not a lot of people know this(In fact I think only me<grin>).The two
digi cameras I've had if I leave them connected to the PC after
downloading piccys to the PC get trickle charged by the USB port

Noticed when I left PC on overnight for downloading but left camera
connected and knew batteries were low.Came back on the morrow to find
fully charged Camera

Also I think it's cheaper to buy and use Li-on re-charegable AA
batteries and a good wall charger(Or a PC<BFG>

 

[kony]

Just buy a regulated universal adaptor at Radio Shack or whatever your
local crapy electronics store is. It will cost about $30 and will work
with a lot more than your camera.

Switching power supplies can get twitchy outside of a their normal load
range. I wouldn't connect one to my camera without doing some stability
tests first.

You're not likely to find a non-switching regulated adapter
worth the 2.5A of the one HP sells, and certainly not at
$30. Almost all semi-regulated adapter in smaller forms
supplying 1.5A or more will be switching.

 

[Al Dykes]

<snip>
although in theory you could use the 3.3v connection of an atx
supply...i don't think it would be worth trying to do so...
as if you made a mistake you could damage your expensive camera...

$50 for that adaptor is of course absurd...
you could prob. find something at radio shack that would work...
however...why not play it safe and simply remove the batteries from the
camera and purchase a seperate charger.

it would certainly be the cheapest and safest thing to do

A PC power supply needs a minimum load so it won't power just
your camera. I also don't know how you'd turn it on since
it's controlled from the mobo.

Look for a power supply on ebay or go to Radio Shack. They sell
wall warts in all sorts of sizes.

 

[Dave]

Radio Shack
3-6.5VDC/2500mA AC-to-DC Adapter
Catalog # 273-1695

Dave

 

[Kevin McMurtrie]

You're not likely to find a non-switching regulated adapter
worth the 2.5A of the one HP sells, and certainly not at
$30. Almost all semi-regulated adapter in smaller forms
supplying 1.5A or more will be switching.

I didn't say that a switching power supply was bad. Nearly all of the
good wall warts are of that kind. The problem is that switching power
supplies are unstable by nature so they sometimes have an operating load
range. An computer power supply designed to deliver 3.3v @ 10A to 50A
might not be stable with a load that varies from 1mA to 1500mA.

 

[James Sweet]

I think I have some random 3.3v SMPS "wall wart" type AC adapters, you'd
probably have to put your own plug on it but if you want one I'd be happy to
send one for a couple bucks to cover packing plus postage.

 

[mike]

Not a lot of people know this(In fact I think only me<grin>).The two
digi cameras I've had if I leave them connected to the PC after
downloading piccys to the PC get trickle charged by the USB port

Noticed when I left PC on overnight for downloading but left camera
connected and knew batteries were low.Came back on the morrow to find
fully charged Camera

Also I think it's cheaper to buy and use Li-on re-charegable AA
batteries and a good wall charger(Or a PC<BFG>

Please disclose your source for Li-on re-chargeable AA batteries
and a charger for same. Please also disclose the prices you've been
paying and your actual personal experience with the setup.
Thanks, mike


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[philo]

A PC power supply needs a minimum load so it won't power just
your camera. I also don't know how you'd turn it on since
it's controlled from the mobo.

to turn on an ATX supply all you need to do is touch the green wire to
ground...
but i still would not adivse doing such

 

[kony]

I didn't say that a switching power supply was bad. Nearly all of the
good wall warts are of that kind. The problem is that switching power
supplies are unstable by nature so they sometimes have an operating load
range. An computer power supply designed to deliver 3.3v @ 10A to 50A
might not be stable with a load that varies from 1mA to 1500mA.

Ah, I misinterpreted what you wrote. That's true, normally
one puts a ~ 2A load on the 5V rail to ensure stabilization,
but it gets much more risky with open-frame swichers, those
not intended for non-integrated usage, not to be hot-plugged
(not that any are, but those with consumer-gear external
cords tend to be designed with such events in mind).

 

[Shep©]

Please disclose your source for Li-on re-chargeable AA batteries
and a charger for same. Please also disclose the prices you've been
paying and your actual personal experience with the setup.
Thanks, mike

Sorry.My mistake they are the Nickel Metal Hydride type which are
still better than the old Ni-cads.

They are the newer common colour Green type in the UK and you can get
them quite a few places.I bought some and a fast charger at a local
market but also, ebay,
http://search.ebay.co.uk/aa-rechargeable-batteries_W0QQsojsZ1QQfromZR40
They don't suffer from the old memory problem of the ni-cads AFAIK

I now have a habit of leaving my digi camera at the side of my PC
plugged in for a session after downloading piccys and the haven't used
the wall charger for ages for the camera

 

[Shep©]

Sorry.My mistake they are the Nickel Metal Hydride type which are
still better than the old Ni-cads.

They are the newer common colour Green type in the UK and you can get
them quite a few places.I bought some and a fast charger at a local
market but also, ebay,
http://search.ebay.co.uk/aa-rechargeable-batteries_W0QQsojsZ1QQfromZR40
They don't suffer from the old memory problem of the ni-cads AFAIK

I now have a habit of leaving my digi camera at the side of my PC
plugged in for a session after downloading piccys and the haven't used
the wall charger for ages for the camera

PS I got the 2500Mh ones

 

[Chief Suspect]

a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

==============

OT, but just had to comment. It is indeed your fault. You should have
voted for somebody else entirely, like I did. Enough of those, and we
would have won. Bush and Gore BOTH were losers! There were other
choices.

 

[Franc Zabkar]

I have a HP M22 camera http://snipurl.com/fd13 , and here are its power
specs:

"Typical power usage: 1.35 Watts with Image Display on. 2.9 Watts
maximum power usage.
Power sources include the following:
. Either two non-rechargeable AA Lithium batteries (included) or two
rechargeable AA NiMH batteries (purchased separately). Rechargeable
batteries can be recharged either in the camera using the optional HP AC
power adapter or optional HP Photosmart M-series dock, or separately in
the optional HP Photosmart Quick Recharger.
. Optional HP AC power adapter (3.3 Vdc, 2500 mA, 8.25 W).
. Optional HP Photosmart M-series dock.
Recharging in camera with the optional HP AC power adapter or optional
HP Photosmart M-series dock: 100% in 15 hours."

HP sells a $50 external power supply for the camera:
HP Photosmart 3.3V AC adapter C8912B http://snipurl.com/fd11 , which
provides 3.3 Volts.

A marking on the camera assigns the + polarity to the center connector
of the jack, and it's a small jack.

Q1: What do you call that kind of jack?

EIAJ DC plug?
http://wagner.net.au/Catalogue/07_15.pdf

Q2: Computer ATX power supplies have a 3.3 V line. I have some old
unused power supplies (and I can buy them nearby for $5). Can I use an
ATX power supply to power the camera?

I'd modify my PC by locating a spare 3.3V plug on my PSU and running a
cable to a slot bracket in an empty slot, or to a hole in the case, or
to an unused 5.25" bay.

WARNING: If you try this, I'd first ensure that the camera's USB
ground and supply negative are at the same potential, otherwise you
may damage your camera if you have both cables connected at the same
time. You can do this by connecting a dummy plug to the DC socket. Use
a DMM to test for continuity between the two grounds. Remove the
batteries while doing this.


- Franc Zabkar

 

[kony]

On Mon, 06 Jun 2005 06:17:44 +1000, Franc Zabkar

WARNING: If you try this, I'd first ensure that the camera's USB
ground and supply negative are at the same potential, otherwise you
may damage your camera if you have both cables connected at the same
time. You can do this by connecting a dummy plug to the DC socket. Use
a DMM to test for continuity between the two grounds. Remove the
batteries while doing this.

I agree that the grounds need be same potential but have you
ever run across any USB GND that wasn't already at power
GND? AFAIK, they all are.

 

[Franc Zabkar]

On Mon, 06 Jun 2005 06:17:44 +1000, Franc Zabkar



I agree that the grounds need be same potential but have you
ever run across any USB GND that wasn't already at power
GND? AFAIK, they all are.

AFAICS, there is no guarantee that the camera's power ground is at the
same potential as its USB ground. What if there is a series polarity
protection diode? Or what if the camera has its own internal SMPS?


- Franc Zabkar