Re: regulated vs unregulated 12v supply

["Keith Doxey" <ukha@xxxxxxx>]

Hi Umar,

Just to confirm what Dave has said...

the power supplies I use for KAT5 are 3-12V unregulated ones.

These have to be set to 9V as they output approximately 12V when 
unloaded dropping to about 11v when connected to KAT5. On the 12V 
setting the output can be as high as 17 volts.

As Dave said, most cameras will have internal regulation to provide 
the correct voltage to the electronics just as KAT5 does. The main 
drawback with a higher voltage is the increase in power dissipated by 
the voltage regulator. Given the small size of these cameras, which 
tend to run quite warm anyway, the extra heat could reduce the life 
of the camera significantly particularly when the ambient temperature 
rises in the summer.

Assuming the power supplies you have identified are switchable to 
lower voltages, try a lower voltage first. Running below the level 
they specify will not damage the camera, it just wont work if the 
voltage is too low. Use the lowest setting that gives reliable 
results and that way you will reduce the heat dissipated within the 
camera.

HTH

Keith


--- In ukha_d@y..., "Dave McLaughlin" <dave@v...>
wrote:
> Hi Umar,
> 
> Most if not all of these cameras regulate internally to +5V with 
7805 type
> regulators and should be able handle up to 24V but they don't 
usually
> specify that. But to be safe I would restrict the input to a max of
13V.
> 
> Why not check the output of the power supply off load first and if
possible
> load it with 250mA and see what the output is. If they are 300mA 
types, then
> the chances are that they will be very close to 12V.
> 
> Regards
> Dave...
> /STANDARD DISCLAIMER
> If you duff the cameras, it ain't my fault guv, honest
> STANDARD DISCLAIMER/
> 
> ----- Original Message -----
> From: <umar@d...>
> To: <ukha_d@y...>
> Sent: Friday, December 06, 2002 3:22 PM
> Subject: [ukha_d] regulated vs unregulated 12v supply
> 
> 
> >
> > Slightly OT, but can anyone help me here.
> >
> > I have installed some 12v 250ma CCTV cameras - they didnt come
with power
> supply !!!!!!!!!
> >
> > I have found some 12v 300mA unregulated power supplies, and 
wonder if they
> will be OK ie not damage the cameras? Reason I ask is they are 1/4
of the
> price of regulated supplies, and as I need 8 of them, difference is
quite
> substantial.
> >
> > Any ideas anyone.
> >
> > Thanks
> >
> > Umar



http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx 
Subscribe:  ukha_d-subscribe@xxxxxxx 
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx 
List owner:  ukha_d-owner@xxxxxxx
List of UKHA Groups here - http://groups.yahoo.com/group/UKHA_Grouplists/

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.