"N_Cook" wrote in message
...
Assuming over-riding the opto couplers to falsely confirm to the system
micro that the arc is struck and the lamp is lit (maybe requiring a delay)
firstly, with the lamp ps disconnected.
Then I intend in the first instance to buy 5x 1.2W white LEDs, 3500K, 20
degree, for proof of concept. Assuming that sort of works then get perhaps
10 more, going down to 2700K or 3000K or perhaps (unlikely) 4000K and
lenses to colimate to 2 degrees. Set inside a reversed conical silvered
glass of an ex-lamp to direct spillover light into the colourwheel/light
tunnel aperture.
The intended LEDs are 11x10mm footprint so can be mounted quite close to
the colourwheel(for 5 anyway) on a spherical back mount. I may as well
retain the original fans, perhapps knocked back a bit for less noise
intrusion later on.

When coming to scaling up I originally was thinking of using a sectored
curvi-linear silvered reflector from PIR units (with faned air cooling)
but have since come across 2 degree lens converters for these LEDs so may
as well go with them and shine directly from a larger spherical backing
mount, directly to the colourwheel aperture.

I'd be interested in any suggestions or comments other than of the I would
not bother type of replies.

Sorry to be one of those people, but based on some experiments that I've
recently been doing with high power LEDs, I think you are going to be
****ing in the wind. A few watts worth is not going to come close. I have
been playing with some 10 watt types with appropriate collimating reflectors
and lenses. Whilst they are 'blinding' to look at directly, you could easily
do it with a pair of sunglasses on. You most certainly could not do that
with a 200 watt discharge lamp. Also, they require substantial amounts of
directly fan-cooled heatsinking, which makes the assembly physically quite
large. A further problem with high power LEDs, is that they are made from
multiple chips on a single die. This actually makes it rather difficult to
get an even density light from them. Because they are substantially
flat-plane light radiators, the light tends to remain in 'dots' through the
collimating and focusing optics.

I do a lot of work on pro and semi pro lighting fixtures - such as moving
heads of the type that you see in use on TV shows like Strictly and
X-Factor. The ones at the small to medium end typically use discharge lamps
in the range 150 to 575 watts. There are now some at the lower end of the
market which use LEDs, and I can tell you that no matter how powerful a LED
that they employ, they cannot hold a candle (Ha!) to the 'real deal' with a
discharge lamp in them.

So, whilst you may get some results that are just about acceptable in the
right circumstances, I honestly feel, based on practical experience, that
you will get anywhere near matching the performance of the discharge lamp
originally fitted.

Arfa