RE: CCTV

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

Thanks Keith, much appreciated.

B.

> -----Original Message-----
> From: Keith Doxey [mailto:ukha@xxxxxxx]
> Sent: 30 July 2001 21:34
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] CCTV
>
>
> 500mA Quick Blow for each cable that you feed.
> That way a fault only kills one circuit.
>
> Fuseholder - Something inexpensive :-)
> Rapid Electronics have suitable ones from
> 26p+vat t  40p+vat so M***** price of around £2-00 :-(
>
> Keith
>
> > -----Original Message-----
> > From: Brian G. Reynolds [mailto:brian.g.reynolds@xxxxxxx]
> > Sent: 30 July 2001 21:04
> > To: ukha_d@xxxxxxx
> > Subject: RE: [ukha_d] CCTV
> >
> >
> > 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 to 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
> > >
> > >
> >
> >
> >
> >
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