RE: CCTV

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

Thanks Keith, some nice ideas, very educational.

I have just re-booted the server after playing musical rack kit and
plugging
it all back in, blimey it's amazing how much kit you acquire! and I'm only
just starting!

All my PC's are mini towers but still have not yet had time to take the
server apart for some measurements.

I will now probably have to start next weekend :-(

Thanks again,

B.

> -----Original Message-----
> From: Keith Doxey [mailto:ukha@xxxxxxx]
> Sent: 29 July 2001 15:53
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] CCTV
>
>
> Hi Brian
>
> > > Depends on the camera. If it has onboard voltage regulation
> > then it should
> > > be OK. If not you may kill it. Als  even if it has onboard
voltage
> > > regulation, dropping the extra voltage willl generate quite
a bit
> > > more heat.
> >
> > Is there anyway to tell this? s  by dropping the voltage it
> generates more
> > heat? even just 3v?
> > is the opposite true as well? give it more voltage and it turns
int  a
> > fridge..............
> > complicated this lecky stuff........
> >
>
> 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.
>
> > Could I therefore take a feed from the PC PSU and feed it t  all
> > the cameras
> > at the same time?
> > I was originally going to put an extension lead with all the
> PSU's plugged
> > int  it and use an appliance module to switch the extension lead
but not
> > sure if it will all fit in the same case, heat might als  be a
problem
> > although I could fit a high-speed cooling fan, I have another
> tray to try
> > just this.
> >
>
> A typical PC power supply can supply over 8A @ 12V. Thats enough for
at
> least 24 cameras.
>
> > What is a wall wart? is it just slang for all PSU's that plug
> > int  the wall
> > and look hideous?
> >
>
> You got it :-)
>
> > Would it be a good idea t  buy a PSU for this job?
> >
> > What fuse should I use? presumably in line with the power cable
in a
> > in-holder?
> >
>
> Neatest way if you are rack mounting is to 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
>
>
> >I have als  bought a 4U case to try and fit my Server int , but
> this needs
> a
> >lot of thinking, something I am loathe to d  on a hot day like t
day.
>
> My original thoughts for doing this were get a Minitower. Remove
> the cover,
> lay it on its side inside the 4U case. Slide the CD & Floppy
forward, draw
> round them to mark the rear of the front panel, cut the holes and bolt
it
> all together. By fitting a "normal" chassis inside it it
means
> any PC config
> changes are easy to d .
>
> I have now decided to use Desktop cases and just use Aluminuim angle
as
> rails to support it in the rack. Short pieces of angle ali as fixing
> brackets pop riveted to the sides of the lid will hold it in place in
the
> rack as the weight would be taken by the rails fixed to the sides of
the
> rack. My Jukebox is a desktop machine and just measured it.... 17.2
inches
> wide so it will fit snuggly between the 19" rails, 5.25"
high so its 3U.
>
> > Sorry for all the questions but you guys are soooooooooooo
clever!
> >
>
> We've als  learnt a LOT from past mistakes :-(
>
> Keith
>
>
>
>
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