The DC version of the 'wall-wart' is rated by voltage and current. They
aren't regulated, so the rating of voltage is the voltage out at the
full rated current. Otherwise, the voltage is higher. So, depending on
how much current the camera was taking, the voltage may have been as
high as 10 or 11 volts. Of course, the same thing happens with the 9V
adapter, its output will be higher and that again depends on what the
current rating of the adapter is and how much the camera is drawing from
it. The short form is that there is a voltage regulator inside the
camera which most likely can handle extra voltage. The possible problem
is that with extra voltage, that regulator is now dissipating extra
heat, this could shorten the lifetime of the camera. To really know
what is happening, you pretty much have to know the internal design.
For all we know, at 8V, it could be marginal, or even greatly underrated.
Bottom line? Most likely it is not going to matter. German design and
most European design tends to be conservative. Most likely the odd
voltage was to increase revenue rather than a design constraint.
Okay, now that I'm interested, here's a thought experiment: Assume that
the camera is probably internally at 5V (they usually regulate batteries
down also for battery life). Assume that the camera sucked up 100ma.
So if the internal regulator is taking 9V in and puts out 5V, there is
4V across the regulator and at 100ma means that the regulator is
dissipating 400mW. Now switch that with, say, an adapter at 12V, the
increase in power would now be an extra 3V at 100ma or 300mW more for a
total of 700mW.
So what does this mean? Run the camera for a while on the 'new' adapter
and see how warm it gets. You might not notice the difference.
Steve
Winterlight wrote:
I have some inexpensive security cameras in my house to watch my Dad who
has Alzheimers. They are German made, wireless, color with audio, day
night, and they use the 2.5Ghz bandwidth which subjects them to
interference . My house is in a bad area for wireless, and range is non
existent beyond 50 feet, and interference is constant. But for my needs
they work great. The cameras have their own DC adaptors but will also
run for around six hours off a nine volt battery. They come with a
little adaptor for this purpose. I suppose you could hook this up
temporarily if you wanted to check on something outside, overnight,
although I haven't tried this.
One of the adaptors went out and I went to replace it. they state 8
volts DC 200ma and this one was only putting out around 6 volts which
meant no picture. I have a lot of old adaptors in my junk box, but 8
volts is an odd amount so I hooked a 9 volt 500ma adaptor and the camera
works better then before with no interference. Obviously, more power
equals more range, which makes me question why they used 8 volts to
begin with?
I would not of attempted the 9 volt upgrade except that they have it set
up to run with a 9 volt battery. With such good results I am considering
upgrading all the cameras. Is the nine volt adaptor putting the camera
at risk, could it blow out the IR LEDs or something?... can any EE in
the group give me some advice?
thanks!
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