RE: CCTV

["Brian G. Reynolds" <brian.g.reynolds@xxxxxxx>]

Keith, sorry t  bug you again but what rating fuse should I use?

Also do you have a favourite panel mount fuse holder? I will look in the
Maplin catalogue and see if I can see anything that looks suitable.

TIA,

B.


> Quick example.
>
> Although the original PSU is 12V @ 300mA, the camera is possibly
> a 9V camera
> drawing 300ma which will have a built in voltage regulator. The
Voltage
> Regulator will be dropping 3V @ 300mA which is 0.9W or 900mW of heat
> disipated by the regulator. If you use a 15V power supply then
> the regulator
> will drop 6V @ 300mA  = 1.8W Whilst the actual regulator may be rated
for
> that power the heatsink may not be able t  dissipate enough of
> the heat and
> the whole camera will run hotter than it should. Heat is the
> biggest killer
> of electronics.
>
>
> A typical PC power supply can supply over 8A @ 12V. Thats enough for
at
> least 24 cameras.
>
> Neatest way if you are rack mounting is t  fit panel mount fuseholders
on
> the front panel.
> If you put an LED and resistor across the fuse it light if the fuse
blows
> indicating a fault, or you can put an LED on the outgoing side of the
fuse
> to show the supple is present.
>
>
> FUSE BLOWN INDICATOR
>  +ve --------fuse------------------device--0V
>
> 	   --LED--Resistor---
>
> or
>
> SUPPLY HEALTHY
>   +ve --------fuse------------------device--- 0V
>
>                     --LED--resistor-------- 0V
>
>