Switching regulators are becoming more popular - they are more efficient and
smaller (fit next to each other), but somewhat more expensive. My D-Link
router came with one which is a good reason to like D-Link. Jameco sells
them also (e.g.,
It turns out that someone *has* designed narrow wall warts!
Jameco carries them; see their 225995, 216442, 249324, 298054, 239564,
190512 and 190511; all 1.8" wide or less. They have others; that list is
What's the easiest way to measure the current drain from the wall wart when
the camera is on and idling, and to measure the voltage to the camera?
Sounds like I need to buy a gizmo from Radio Shack.
I am surprised that you do not have a DVM (or a VOM).
Depending on (possible) future useage, you could get an el-cheapo VOM
from the likes of harbor freight (about $2) or at R.S. (about $25); for
a good DVM at prices better than at R.S., try Jameco.
Look for meters that have 2 or more current ranges not counting a 10
amp range; the R.S. $15 VOM has only one range (150mA) and may not be
adequate for this application.
The Jameco DVMs go from about $10 and up.
Looks like you found out already that I'm way more of a programmer than an
electronics guy. :) Although I have soldered together one or two
electronics kits in my time.
I just picked up an "auto-ranging" Multimeter from Radio Shack today. It
say it measures AC/DC voltage levels, current, and resistance, and has a
diode checker. Is that what I need? Not sure what DVM and VOM mean.
The fun part is going to come when I make my DID (Duck Irritation Device) an
airboat. A long time ago I bought this UFO toy which was basically a big
helium baloon with two radio controlled propeller fans in a plastic housing,
taped to the bottom of the baloon. I pulled the propeller fans out of the
plastic housing and as soon as I get my new connector lead set, I'll be
hooking them up to my Lego Mindstorm RCX brick computer. The RCX brick was
too heavy to be connected to the helium baloon (that would have been fun!),
but I'm betting that in a lightweight small boat; the two fans should make
it move pretty fast. I'll put the wireless transmitter camera in the boat
too. My biggest design problem is having a failsafe so if a duck gets mad
and sinks my boat, I don't lose everything! :)
Funny you should say that. My next Robosapien movie shows an actual duck
attacking my Robosapien.
If you never saw my first Robosapien movie you can see it at:
Be forewarned it's *really* silly.
The other replies you have received assume that the wall wart is providing a
voltage which is regulated further in your device. This may not necessarily
be the case and, if it is not, you may damage your camera.
Almost a false assumption on your part.
Almost all wall warts are *unregulated* and all of those have an
excessively high output voltage which increases as the loading decreases
from rated value.
Output voltage could be 14 to 16 or more volts in his application.
What's "almost a false assumption"? It's no assumption that almost all of
the other replies assume that the wall wart he has is unregulated. It's
also not an assumption that there are regulated wall warts. I have several.
I also have a regulated switching wall wart. It's irresponsible of you to
give someone the advice to replace their power supply without even asking
him whether it's regulated or not. But, it's not your camera, right?
Well, excuse me!
I know damn well that there are regulated wall warts - both switchers
and linears; hence the care in the wording.
It is obvious that the camera has its own regulator inside; camera
batteries range from 3V to 6V.
Thus an extra expense of regulation in the wall wart leads to lower
profits to the maker.
The "worst case" scenarios are:
1) Unregulated (extremely high probability) wall wart, 16 to 18V to
A 12V battery replacement cannot possibly damage the camera and will
work well down to the indicated 10.2V as represented in the datasheet i
2) Regulated wall wart, 12V to camera.
Again a 12V battery replacement will do well.
Many of the battery chemistries discussed have initial actual voltages above
12V for a nominal 12V configuration. If the camera expects regulated 12V
these could damage it. I agree it's unlikely, but in light of the scope of
the other data and advice being offerred, it is surprising that no one is
even concerned about this.
If you need the assembly small, unless you want it operate for very
short period of time, the only way to go is with a high-efficient
type. There is an article on Matt Blaze's page (about chargers, but it
also covers batteries):
(high efficient would be NiMH for rechargables, these are the
cost-effective ones, not because they are cheap - the good quality
ones are not - but because they can be reused). You will need 8-9
batteries serialized for this (the voltage of NiMH is slightly less
than 1.5V) and if the TX is not of high quality, the transmission
frequency may drift through operation (I have this problem with some
of the mini-TX cameras that were sold in Toronto over the X-mas - they
wer only $40 - TX/RX and worked on 9V batteries but could not
stabilize the transmission in time).
On Thu, 3 Feb 2005 20:20:23 -0500, "Robert Oschler"
While there are some pretty elaborate systems available, the last ROV
I built used a 12V single board camera from Supercircuts. My power
supply was a battery holder for 8 AA's and a set of rechargable
alcaline. I didn't bother with a fuse or regulator. Just wired it
frome the battery pack, through a switch, and to the camera. I get
about 6 to 8 hours from the pack before I remove the batteries, drain
them in a flashlight, and recharge them.
I've been using this system for about 3 years without ruining the
camera. Most of the small cameras out now seem to be able to handle a
pretty wide range of voltage. My current ROV project uses a small
color cmos camera. It's specs say 9vdc, but it seems to run on
anything from 7.2v up to 12v. I use a 9v battery for convenience.
You should be able to get a battery holder and some rechargable AA's
with a charger at any radio shack.
Got any pictures of your ROV or video? I'd like to post them on my robot's
site; especially if you have a write-up on it. If nothing else, stop by the
forum and register, and I'll add you to the Member Sites list with a link to
your ROV web page (if you have one).
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