For an art installation: Two lanterns will project slightly different images from glass slides onto the same screen. One should fade up as, or after, the other fades down. The difficult bit is that this needs to happen automatically every few minutes, as the installation is to stand unattended as part of a gallery display.

When the lanterns were built they would have been lit by oil or gas; the plan is to use GU10 leds of about 5W 27deg beam behind each slide. Although low wattage dimmers are sold for these I cannot find anything which would do the job automatically. I have seen a string of fairy leds which fade up and down on their own though...

Any ideas where to look?

On 31/05/2014 13:55, Peter wrote:
For an art installation: Two lanterns will project slightly different images from glass slides onto the same screen. One should fade up as, or after, the other fades down. The difficult bit is that this needs to happen automatically every few minutes, as the installation is to stand unattended as part of a gallery display.

When the lanterns were built they would have been lit by oil or gas; the plan is to use GU10 leds of about 5W 27deg beam behind each slide. Although low wattage dimmers are sold for these I cannot find anything which would do the job automatically. I have seen a string of fairy leds which fade up and down on their own though...

Any ideas where to look?

It would be some fairly simple control electronics to do this -
basically PWM so that one LED is on and the other is off.

Then set it up so that after a period one fades up as the other fades
down. For a pair with fade in/out you can have just one bipolar driven
output with one LED connected to +V and the other to OV.

Asking in one of the electronics groups will get you pointers to a
suitable circuit. BTW are you sure you don't want to use batwing bare
LEDs of about 5W - they are a much better approximation to a point
source than a GU10 (need heatsinking to stay alive though).

--
Regards,
Martin Brown

On Sat, 31 May 2014 05:55:54 -0700 (PDT), Peter
wrote:

Any ideas where to look?

Ideal project for an Arduino so possibly your local school might use
it as a class project or do you have any hackerspaces (hackspaces) or
Makers near you? http://www.hackspace.org.uk/view/Main_Page

On Saturday, May 31, 2014 1:55:54 PM UTC+1, Peter wrote:

For an art installation: Two lanterns will project slightly different images from glass slides onto the same screen. One should fade up as, or after, the other fades down. The difficult bit is that this needs to happen automatically every few minutes, as the installation is to stand unattended as part of a gallery display.
When the lanterns were built they would have been lit by oil or gas; the plan is to use GU10 leds of about 5W 27deg beam behind each slide. Although low wattage dimmers are sold for these I cannot find anything which would do the job automatically. I have seen a string of fairy leds which fade up and down on their own though...
Any ideas where to look?

Many possible solutions exist. None are ready made afaik, so it'll take time & money.


NT

Peter wrote:
For an art installation: Two lanterns will project slightly different
images from glass slides onto the same screen. One should fade up as,
or after, the other fades down. The difficult bit is that this needs
to happen automatically every few minutes, as the installation is to stand
unattended as part of a gallery display.
Any ideas where to look?

A small lighting controller with a programmed repeating fade - try the lighting forum at www.blue-room.org.uk

Owain

On Saturday, 31 May 2014 13:55:54 UTC+1, Peter wrote:
For an art installation: Two lanterns will project slightly different images from glass slides onto the same screen. One should fade up as, or after, the other fades down. The difficult bit is that this needs to happen automatically every few minutes, as the installation is to stand unattended as part of a gallery display.



When the lanterns were built they would have been lit by oil or gas; the plan is to use GU10 leds of about 5W 27deg beam behind each slide. Although low wattage dimmers are sold for these I cannot find anything which would do the job automatically. I have seen a string of fairy leds which fade up and down on their own though...



Any ideas where to look?

Thanks for all ideas. I am out of my depth with electronics but following Peter's suggestion found a Build/Hacker group just around the corner from me! - had never heard of them. Hoping for an interested maker..

On 31/05/2014 13:55, Peter wrote:
For an art installation: Two lanterns will project slightly different images from glass slides onto the same screen. One should fade up as, or after, the other fades down. The difficult bit is that this needs to happen automatically every few minutes, as the installation is to stand unattended as part of a gallery display.

When the lanterns were built they would have been lit by oil or gas; the plan is to use GU10 leds of about 5W 27deg beam behind each slide. Although low wattage dimmers are sold for these I cannot find anything which would do the job automatically. I have seen a string of fairy leds which fade up and down on their own though...

Any ideas where to look?

Have you considered a mechanical solution rather than an electronic one?

Something like a frosted glass plate of varying opacity which is moved
between lamp and slide, perhaps. Could either slide up and down or
rotate - depending on shape and layout.
--
Cheers,
Roger
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In article ,
writes:
On Saturday, May 31, 2014 1:55:54 PM UTC+1, Peter wrote:
For an art installation: Two lanterns will project slightly different images from glass slides onto the same screen. One should fade up as, or after, the other fades down. The difficult bit is that this needs to happen automatically every few minutes, as the installation is to stand unattended as part of a gallery display.
When the lanterns were built they would have been lit by oil or gas; the plan is to use GU10 leds of about 5W 27deg beam behind each slide. Although low wattage dimmers are sold for these I cannot find anything which would do the job automatically. I have seen a string of fairy leds which fade up and down on their own though...
Any ideas where to look?
Many possible solutions exist. None are ready made afaik, so it'll take time & money.

Back in the days of slide projector presenations, 2-projector cross-fading
was a standard practice, with alternate slides loaded into each projector's
carrossel, to give no break between slides. Slide change always took place
in the dark whilst the other projector was showing its image. It was
particularly good for build-up slides, but in any case looked more
professional than single projector slide changes.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Sound to light displays? Discos used to have this effect where one colour
faded to another a lot.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Peter" wrote in message
...
For an art installation: Two lanterns will project slightly different images
from glass slides onto the same screen. One should fade up as, or after, the
other fades down. The difficult bit is that this needs to happen
automatically every few minutes, as the installation is to stand unattended
as part of a gallery display.

When the lanterns were built they would have been lit by oil or gas; the
plan is to use GU10 leds of about 5W 27deg beam behind each slide. Although
low wattage dimmers are sold for these I cannot find anything which would do
the job automatically. I have seen a string of fairy leds which fade up and
down on their own though...

Any ideas where to look?

Ah, memories. I can remember at school, a clever magic lantern slide,
presumably with its levers made out of a transparent substance, ehre if you
cranked a handle a horse appeared to gallop .

Of course when cine arrived all of this stuff was killed off.
The light in the one we saw seemed to have had some kind of fuel, but it
smelt terrible. I bet health and safety would not allow it near a school
today!

Brian

--
From the Sofa of Brian Gaff Reply address is active
"Peter" wrote in message
...
For an art installation: Two lanterns will project slightly different images
from glass slides onto the same screen. One should fade up as, or after, the
other fades down. The difficult bit is that this needs to happen
automatically every few minutes, as the installation is to stand unattended
as part of a gallery display.

When the lanterns were built they would have been lit by oil or gas; the
plan is to use GU10 leds of about 5W 27deg beam behind each slide. Although
low wattage dimmers are sold for these I cannot find anything which would do
the job automatically. I have seen a string of fairy leds which fade up and
down on their own though...

Any ideas where to look?

"Brian Gaff" wrote in message
...
Ah, memories. I can remember at school, a clever magic lantern slide,
presumably with its levers made out of a transparent substance, ehre if
you cranked a handle a horse appeared to gallop .

Of course when cine arrived all of this stuff was killed off.
The light in the one we saw seemed to have had some kind of fuel, but it
smelt terrible. I bet health and safety would not allow it near a school
today!


yup, the only foul smelling things found in schools nowadays (apart from the
feral kids) comes from the bogs where the pupils are smoking squidgy black.

On 31/05/2014 20:29, Roger Mills wrote:
On 31/05/2014 13:55, Peter wrote:
For an art installation: Two lanterns will project slightly different
images from glass slides onto the same screen. One should fade up as,
or after, the other fades down. The difficult bit is that this needs
to happen automatically every few minutes, as the installation is to
stand unattended as part of a gallery display.

When the lanterns were built they would have been lit by oil or gas;
the plan is to use GU10 leds of about 5W 27deg beam behind each slide.
Although low wattage dimmers are sold for these I cannot find anything
which would do the job automatically. I have seen a string of fairy
leds which fade up and down on their own though...

Any ideas where to look?

Have you considered a mechanical solution rather than an electronic one?

Something like a frosted glass plate of varying opacity which is moved
between lamp and slide, perhaps. Could either slide up and down or
rotate - depending on shape and layout.

It would be more in keeping with the lanterns.

Colin Bignell

On 01/06/2014 19:13, Nightjar wrote:
On 31/05/2014 20:29, Roger Mills wrote:
On 31/05/2014 13:55, Peter wrote:
For an art installation: Two lanterns will project slightly different
images from glass slides onto the same screen. One should fade up as,
or after, the other fades down. The difficult bit is that this needs
to happen automatically every few minutes, as the installation is to
stand unattended as part of a gallery display.

When the lanterns were built they would have been lit by oil or gas;
the plan is to use GU10 leds of about 5W 27deg beam behind each slide.
Although low wattage dimmers are sold for these I cannot find anything
which would do the job automatically. I have seen a string of fairy
leds which fade up and down on their own though...

Any ideas where to look?

Have you considered a mechanical solution rather than an electronic one?

Something like a frosted glass plate of varying opacity which is moved
between lamp and slide, perhaps. Could either slide up and down or
rotate - depending on shape and layout.

It would be more in keeping with the lanterns.

Colin Bignell

Indeed.
--
Cheers,
Roger
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Please reply to Newsgroup. Whilst email address is valid, it is seldom
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