Hello,

I'm installing a socket in my living room ceiling for a projector, I'd
also like to install a wall switch to turn off the projector when not in
use (rather than leave it in standby the whole time). Projectors need at
least 5 minutes to cool down before being switched back on after switch
off, I'd like a switch that will enforce this delay. I've been unable to
find any such "restart delay" switch from rs components, maplin or farnell.

The closest thing I've found is this industrial relay, which I guess I
could use with a standard wall switch, but it's probably expensive and
will take much more effort to install:

http://www.ferret.com.au/articles/1c/0c00ef1c.asp
http://www.comat.ch/zeitrelais/e/det...p?EDV_Nr=12893

Is such a relay my only option or is there a cheaper domestic option
which does the same thing?

Thanks in advance for any help or advice.

--
drbob

OE Users - check this out!
http://home.in.tum.de/~jain/software/oe-quotefix/

remove spamblock. to mail me

The closest thing I've found is this industrial relay, which I guess I
could use with a standard wall switch, but it's probably expensive and
will take much more effort to install:

You can get DIN rail units for timing communal stair areas. These are
usually used with momentary switches to give several minutes delay. However,
I wouldn't be surprised if they could be used with a latching switch. You'd
need to check that the delay starts from when the switch is released, not
upon initial press. The DIN rail unit could be mounted in a small enclosure
next to the projector.

An example is the MK 5650S.
http://www.mkelectric.co.uk/products...5&rangeid=1051

It is designed mainly for resistive lighting loads and extractor fans.
However, a projector is largely a resistive load for the bulb and a fan
motor, so I reckon it would probably be OK, provided it doesn't switch off 5
minutes after you turn it on, rather than off.

Christian.

In article ,
drbob writes:
Hello,

I'm installing a socket in my living room ceiling for a projector, I'd
also like to install a wall switch to turn off the projector when not in
use (rather than leave it in standby the whole time). Projectors need at
least 5 minutes to cool down before being switched back on after switch
off, I'd like a switch that will enforce this delay. I've been unable to
find any such "restart delay" switch from rs components, maplin or farnell.

Seems like the projector should include such protection internally
if it's required. I assume the issue is with the circuitry not being
able to hot-restrike the lamp, which typically requires some 10 times
the cold strike voltage.

In this case perhaps something based on preventing switchon whilst
it's still hot might be more appropriate than a timer? This could be
done with a slight modification to a fail-safe relay, whereby a
thermostat was added in series with the energize circuit.

--
Andrew Gabriel

In article ,
drbob wrote:
Is such a relay my only option or is there a cheaper domestic option
which does the same thing?

Very easy to build using bits from Maplin, etc. Based around a 555 timer.

I'd estimate 25 quid for a 10 amp load one.

To make things even easier, they do a kit designed for the purpose.

VF 08 at 14.99 plus the cost of a suitable power supply.

--
*A nest isn't empty until all their stuff is out of the attic

Dave Plowman London SW
To e-mail, change noise into sound.

On Wed, 20 Jul 2005 10:16:11 GMT, drbob wrote:

I'd like a switch that will enforce this delay. I've been unable to
find any such "restart delay" switch from rs components, maplin or
farnell.

I doubt you'll find a normal type switch do that but

The closest thing I've found is this industrial relay,

There are many things in this line what you want is one with a
non-retrigerable monostable (I think...). You should be able to find
that and one with changeover contacts. They are DIN rail mounting but
a small enclosure isn't much or just mounted in a box.

it's probably expensive and will take much more effort to install:

ISTR that they are quite cheap =A320 to =A330 and the extra installation=

effort of mounting a box and a few more terminations isn't great...

--
Cheers
Dave. pam is missing e-mail

"drbob" wrote in message
m...
Hello,

I'm installing a socket in my living room ceiling for a projector, I'd
also like to install a wall switch to turn off the projector when not in
use (rather than leave it in standby the whole time). Projectors need at
least 5 minutes to cool down before being switched back on after switch
off, I'd like a switch that will enforce this delay. I've been unable to
find any such "restart delay" switch from rs components, maplin or
farnell.

Normally projectors need the mains to be kept on for a few minutes after you
have operated their off switch.
This allows the fans to continue to cool the interior and/or lamp.
You should never switch them off at the mains before they have gone through
their shut down period as it reduces their life.

So what you actually want is a delayed switch off not a delayed switch on.

So what you actually want is a delayed switch off not a delayed switch on.

Yes. I misread the original request and solved the keeping the mains on long
enough problem!

Christian.

In article ,
Andrew Gabriel wrote:
Seems like the projector should include such protection internally
if it's required. I assume the issue is with the circuitry not being
able to hot-restrike the lamp, which typically requires some 10 times
the cold strike voltage.

They all do - or rather I think they do. Certainly my DLP back projection
TV does. But it obviously relies on just going to standby, as removing the
mains entirely would require a back-up battery to run the fan, which runs
for some minutes after switch off.

But if you do, it won't re-strike until it's happy.

--
*OK, who stopped payment on my reality check?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Christian McArdle wrote:
So what you actually want is a delayed switch off not a delayed switch
on.

Yes. I misread the original request and solved the keeping the mains on
long enough problem!

Same here. I don't think it will re-start until it's happy to do so, but
unplugging it before it's ready would be a bad thing too.

--
*Failure is not an option. It's bundled with your software.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
Christian McArdle wrote:

So what you actually want is a delayed switch off not a delayed switch
on.


Yes. I misread the original request and solved the keeping the mains on
long enough problem!


Same here. I don't think it will re-start until it's happy to do so, but
unplugging it before it's ready would be a bad thing too.


I was told by the place I bought the projector that as long as the pj
isn't moved and is given at least 5 minutes to cool, it doesn't matter
when it is switched off at the mains and the fan just helps it cool more
quickly (it delays restart around 90 seconds when put into standby), is
this definately wrong?.

My pj is a budget model and I'm not sure if the delayed restart it
enforces when in standby is a simple timer or if it does actualy check
the lamp temperature before attempting to restrike the lamp.

With a delayed power *off* rather than delayed restart, someone could
take the lamp out of standby after it has been switched off at the wall,
only to have the power suddenly cut a couple of minutes later. The
instinctive reaction then would be to immediately switch it back on at
the wall - if the pj doesn't check the lamp temperature on startup, then
this scenario could damage it.

--
drbob

OE Users - check this out!
http://home.in.tum.de/~jain/software/oe-quotefix/

The post-lamp-off cooling requirement very much depends on your exact
projector make and model but the problem is generally that the bit that
matters - the anode and cathode of the lamp - requires forced air
cooling for a considerable time after being switched off. Cutting off
the mains during this time stops this cooling and stresses the lamp but
whether it leads to premature failure is hotly debated.
Most high pressure lamps will restrike for a few seconds after switch
off and again once cool but generally the lamps power supply won't be
able to generate a high enough voltage to strike the lamp when it's
warm but not hot. I can't see why it would matter to try to strike the
lamp in this state and to the best of my knowledge no-one designs
circuitry to protect against this if you remove mains and reapply it.
So the issue is not that you shouldn't switch it back on too soon after
switch off but rather that you shouldn't remove the mains before it's
properly cooled down.

Calvin wrote:
So the issue is not that you shouldn't switch it back on too soon after
switch off but rather that you shouldn't remove the mains before it's
properly cooled down.

Thank you very much for that explanation. It seems the shop I bought the
pj from didn't know what they were talking about. Was their advice never
to move a projector until it is fully cooled down also incorrect?

--
drbob

OE Users - check this out!
http://home.in.tum.de/~jain/software/oe-quotefix/

drbob wrote:

I'm installing a socket in my living room ceiling for a projector, I'd
also like to install a wall switch to turn off the projector when not in
use (rather than leave it in standby the whole time). Projectors need at
least 5 minutes to cool down before being switched back on after switch
off, I'd like a switch that will enforce this delay. I've been unable to
find any such "restart delay" switch from rs components, maplin or farnell.

Projectors usually include an auto off feature. Press 'menu' on the
remote, it should be somewhere amoung the options.


--
David Clark

$message_body_include ="PLES RING IF AN RNSR IS REQIRD"

drbob wrote:
Calvin wrote:

So the issue is not that you shouldn't switch it back on too soon after
switch off but rather that you shouldn't remove the mains before it's
properly cooled down.


Thank you very much for that explanation. It seems the shop I bought the
pj from didn't know what they were talking about. Was their advice never
to move a projector until it is fully cooled down also incorrect?


As I understand it...

Calvin's explaination is accurate and should be considered carefully.
However, different manufacturers seem to place different focus on the
power-down / power-up procedure. The best advice I can offer is to visit
the manufacturer's website or read the manual.

Regarding the movement, the only thing I can think of is that the
envelope of the lamp will be more susceptible to damage during the
cooling cycle if jarred abruptly.

Have a search on Sanyo's website (I've been there since owning a Sanyo
PLV-Z2 projector for the last 8 months) - they have a nice
FAQ/horror-story about the effects of power-cycling the lamps.

My own advice would be - forget the ancillary device to maintain power
to your PJ and adopt a common-sense approach to the PJ (remember, a
spare lamp could cost upwards of £300). Also consider a cheapish UPS -
despite your best efforts you never know when a power cut could occur; I
have a small Belkin UPS (around £70) that feeds the PJ, Sky and DVD
recorder from battery backup (at around 50% full load) and has filtered
(non-backed-up) outlets for the TV (still need it!), AV-receiver and the
various format converters used to feed the PJ. That way, I hope to be
able to shut down the PJ without the loss of cooling should a power cut
occur.

Mike

As far as post-off lamp cooling is concerned my advice is to apply
common sense but also to relax a bit. Consistently turning the
projector off by pulling the plug is asking for trouble (although still
not guaranteeing you'll get it). Occasionally suffering a power cut or
killing the mains a little while after a lamp off won't do any harm so
it's really not worth having a UPS.

The shop gave you good advice about not moving the projector while it's
hot. Lamps run very hot and so generate enormous internal pressures.
Obviously when they are in their highly pressurised state they are more
stressed so more prone to break if jarred. If (when) you ever change
the lamp take heed of the warning notice that will say to let the lamp
cool completely before handling. UHP lamps (probably what you'll have
in a domestic projector) are quite safe when cold but consider them a
bomb when hot.

If you really want to look after your projector do two things.
Give up/don't start smoking. It coats the optics.
Clean the filters regularly. If it can't get air in it can't stay
cool.

In article .com,
"Calvin" writes:
UHP lamps (probably what you'll have
in a domestic projector) are quite safe when cold but consider them a
bomb when hot.

Many are bombs when cold too -- internal pressure can still be above
atmospheric. If you drop or scratch them, they can still explode.

--
Andrew Gabriel

You're correct Andrew, that was poor advice from me. While cold lamps
are a lot safer than hot ones they should be treated with great respect
(I usually call them "Sir").

Dave Liquorice wrote:

There are many things in this line what you want is one with a
non-retrigerable monostable (I think...). You should be able to find
that and one with changeover contacts. They are DIN rail mounting but
a small enclosure isn't much or just mounted in a box.

If you were going to go to the bother of custom building, then I would
include a inhibition of turning the power off while on load as well
since most projectors require a controlled run down and cooling off period.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Calvin wrote:
As far as post-off lamp cooling is concerned my advice is to apply
common sense but also to relax a bit. Consistently turning the
projector off by pulling the plug is asking for trouble (although still
not guaranteeing you'll get it). Occasionally suffering a power cut or
killing the mains a little while after a lamp off won't do any harm so
it's really not worth having a UPS.

The shop gave you good advice about not moving the projector while it's
hot. Lamps run very hot and so generate enormous internal pressures.
Obviously when they are in their highly pressurised state they are more
stressed so more prone to break if jarred. If (when) you ever change
the lamp take heed of the warning notice that will say to let the lamp
cool completely before handling. UHP lamps (probably what you'll have
in a domestic projector) are quite safe when cold but consider them a
bomb when hot.

If you really want to look after your projector do two things.
Give up/don't start smoking. It coats the optics.
Clean the filters regularly. If it can't get air in it can't stay
cool.


Might be worth looking at

http://www.sanyo.co.uk/scripts/hsrun...rt=HS_FSGen_US

point (41) - especially the last sentence re. power cuts. That's the
basis of my advice (based only on the recommendations from the
manufacturer of my projector).

The point on smoking is a good point, too.

PS. ********, that link doesn't work - dynamic page contents...

Here's the text, anyway, can be found by going to links Business /
Projectors / Home Cinema / FAQ

41. What causes lamp failure?
Although it is hoped that a projector lamp will continue to operate
satisfactorily throughout its anticipated working life, it has to be
accepted that failure may occur before that anticipated time has
elapsed. General Failu The lamp in a projector is categorised as a
consumable item, and even with proper use and maintenance a small
proportion of lamps may fail well before their expected life span has
elapsed. Neither the life expectancy nor the performance of a lamp can
be guaranteed, and the duration of its useful operation will depend to a
large extent on the conditions under which it operates. Usage Failu
As a projector lamp ages, the ends of the two electrodes within the
strike chamber cavity gradually erode and the gap between them slowly
increases. Erosion of these electrodes will occur every time the lamp is
started and eventually, a point is reached at which the Ballast Power
Unit can no longer supply the amount of current demanded by the lamp in
order to strike and maintain the arc between the electrode tips. It is
at this stage that performance deteriorates, with the light output
falling off , the lamp starting to flicker at switch on or going out
soon after strike up, or even failing to come on at all. Temperature
Failu Two factors that always result in high lamp glass temperatures
are the non-adherence to correct power down procedures, and blocked or
partially blocked air filters. It is essential that the projector be
powered down properly after use in order to allow the cooling fans to
reduce the lamp temperature sufficiently. The hottest part of a working
lamp is the strike stem containing the two electrodes, and if the
airflow over the lamp is in any way restricted by blocked filters,
temperatures around the strike chamber will rise sufficiently to soften
the glass. The usual consequence of this is that the pressurised strike
chamber balloons outwards at its weakest point, producing a bulge or
swelling in the stem. The stem itself is pulled off axis as a result,
effectively moving the strike area away from the focal point of the
reflector. Elevated temperatures can also generate microcracks in the
stem, allowing the ingress of air that is then burned by the heat from
the lamp arc, usually leaving black oxide deposits on the internal
surfaces of the chamber walls as well as on the strike electrodes. The
microcracks grow rapidly, and after a very short time the integrity of
the structure is compromised and the stem shatters. Any mains voltage
interruption or power cut, however momentary, will produce similar
results to those outlined obove.

On Thu, 21 Jul 2005 03:01:34 +0100, John Rumm wrote:

If you were going to go to the bother of custom building, then I
would include a inhibition of turning the power off while on load as
well since most projectors require a controlled run down and cooling
off period.

I'm sure that the programmable/timer relays you can buy off the shelf
will do that. See what RS have to offer.

--
Cheers
Dave. pam is missing e-mail

DJC wrote:

Projectors usually include an auto off feature. Press 'menu' on the
remote, it should be somewhere amoung the options.


My projector can't switch itself off entirely via the remote, it will
only go into standby mode, the pj enforces a cooling off period before
it will come back out of standby, this doesn't apply if I switch off at
the mains. My worry was that I (or another family member) may
inadvertently damage the projector by switching off the mains at the
wrong time.

--
drbob

OE Users - check this out!
http://home.in.tum.de/~jain/software/oe-quotefix/

On Fri, 22 Jul 2005 22:28:01 GMT, drbob wrote:

My worry was that I (or another family member) may inadvertently
damage the projector by switching off the mains at the wrong time.

So don't make the mains to the projector switchable via an easy to get
at switch. Hide it out of the way so the eays way to turn it off is
via the menus or it's remote.

You should be able to find a delayed off relay though. Why do I have a
sneaky feeling that this is the opposite requirement to what was
orginally asked?

--
Cheers
Dave. pam is missing e-mail

Dave Liquorice wrote:
On Fri, 22 Jul 2005 22:28:01 GMT, drbob wrote:


My worry was that I (or another family member) may inadvertently
damage the projector by switching off the mains at the wrong time.


So don't make the mains to the projector switchable via an easy to get
at switch. Hide it out of the way so the eays way to turn it off is
via the menus or it's remote.

You should be able to find a delayed off relay though. Why do I have a
sneaky feeling that this is the opposite requirement to what was
orginally asked?



From elsewhere in theis thread, I've established that what is important
is for the cooling fan to be allowed to run for a few munites after
switch off. For a truly idiot proof switch I'd need a relay that refuses
to cut power whilst under high load (lamp on) and then will only cut
power after a 5 minute delay from the point the high load ends.

--
drbob

OE Users - check this out!
http://home.in.tum.de/~jain/software/oe-quotefix/

In article ,
drbob wrote:
From elsewhere in theis thread, I've established that what is important
is for the cooling fan to be allowed to run for a few munites after
switch off. For a truly idiot proof switch I'd need a relay that refuses
to cut power whilst under high load (lamp on) and then will only cut
power after a 5 minute delay from the point the high load ends.

Why not just put the poor thing into standby?

--
*I just got lost in thought. It was unfamiliar territory.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
drbob wrote:

From elsewhere in theis thread, I've established that what is important
is for the cooling fan to be allowed to run for a few munites after
switch off. For a truly idiot proof switch I'd need a relay that refuses
to cut power whilst under high load (lamp on) and then will only cut
power after a 5 minute delay from the point the high load ends.


Why not just put the poor thing into standby?


Well I can do that already, but it wastes power, not much I know - but
since I'm planning the installation of this ceiling socket I wanted to
look into the feasibility of a foolproof switch for the power socket.
The alternative, already stated elsewhere on the thread is to put the
switch somewhere inaccessible so it only gets used by me when the pj
isn't used for long periods.

--
drbob

OE Users - check this out!
http://home.in.tum.de/~jain/software/oe-quotefix/