lampledlight
I have a 1080p projector and I want to change the regular 230w lamp for a LED lamp that uses less energy and lasts longer.
How complex would this be? LED projectors with these specs are ridicously expensive, but only a few unknown brands offer them. Some have design issues and overheat or break.
I don't know why most companies don't offer these, maybe the money is in spare bulbs which can be as much as half what a new projector costs.
The problem here is one of scale.
The way an LED works is that the electrons jump from the N side to the P side of the semiconductor junction, and as they do so some of the electrons fall into 'holes' in the P side. This changes their energy level, and causes the discharge of a photon - ie, light.
This means that:
Yes, you can have multiple LEDs in a 'bulb' to give a larger amount of light, and to provide a more diffuse shadow pattern, but still as the light diffuses it gets very much dimmer. It then becomes a problem of sheer bulk - trying to get enough LEDs into a small enough area to give enough light at a reasonable distance.
That is why they work OK in a table lamp at close range, but at longer range (the ceiling) they are next to useless.
An LED solution is almost certainly going to suit you better than using filament lamps. LEDs take somewhat more effort to use than lamps in this application - but you will always be happy with the result once you forget what it took to implement.
BUT - lamps first
Digikey sell 28V and other lamps
Including lamps from Chicago miniature lighting.
This spec sheet from CML shows 7 x 28 V lamps in T-3 3/4 wedge base design with currents of 70 MA to 200 mA. That's only one Digikey inspired example. Many more.
You could use 24 V automotive bulbs with a small series resistor (R~= 4/I ohms)
You could use 2 x 12V automotive bulbs in series plus a small R (perhaps more available).
You could use 1 x 12V bulb with larger R. (R~= 16/I. Power rating or resistor = 2 x P bulb.)
BUT
LEDS:
As you have MCU controlled relays, operating the LEDs from the MCU supply or similar low voltage supply and driving them from the MCU drive to the relays makes most sense.
Power at 28V and 0.2A = V x I = 28 * .2 = 5.6 Watts.
A 5 Watt lamp is about car tail light bright.
If you used 5 Watts for a LED you could utterly dazzle your viewers.
Far less power will be adequate.
I'd suggest that even 1 Watt would be very adequate for an LED (lights up a small room) and even much much less would probably suffice. If you wished you could use several LEDs in series, which has some advantages.
If you did need to operate the LEDs from 28 VAC, starting with a resistively driven LED, 50 mA would give you "lots of light". Something like a 270 ohm resistor and series diode and probably a capacitor at the LED would drive this. R value needs to be checked due to half wave AC effects on average current, For an LED an NSPWR70CSS-K1 from Nichia will produce approaching 20 lumen at this drive level.
Ideally you'd use a buck converter to reduce the voltage from 28 VAC. LED driver boards that will drive up to eg 350 mA LEDs can be had on ebay and elsewhere for under (or well under) $5. Deal Extreme sells a number of potentially suitable parts.
Example only - ebay 3 Watt LED driver, up to 24V in - use a series R and diode and cap.
$1.94 each.
Operation from eg 5 Volts requires an eg ULN2803 (costs a few dollars US) to drive up to 8 LED drivers plus a resistor per LED. ULN2803 input can be driven by microcontroller directly OR from 28 VAC using 1 diode, 1 resistor and 1 small capacitor.
Best Answer
You'd need to provide brand and model of projector and bulb plus web links.
What you need to know, at least, is ANSI lumen rating of projector and present technology and rating.
All that said, this is getting more viable but is not something attempted lightly. The fact (as you recount it) that available solutions are from unknown makers and that they don't work may be because the conspiracy theory re bulbs is correct, but may also tell you something re difficulty.
Modern data projector bulbs are often "HID" (High Intensity Discharge) technology which is also found in car headlamps. This uses a small arc in eg Xenon gas with extremely high voltages and control gear to operate. (Bulb resrike when hot may required 10 kV+). HID bulbs for automotive use MAY provide a chaper projector solution but also may not - they are also qite expensive - but not as bad as projector bulbs generally.
Assume you have a 2000 ANSI lumen projector. This used to be a high spec but now is only OK for home theater etc. Assume that 50% of your 'bulb' light gets to the screen. That may be optimistic. Modern leading edge higher power LEDs are approaching 150+ lumen/Watt delivered. More realistically if you am at an out-of-module level of 100 l/W you are doing OK. So the LED wattage needed =
In production volumes you can get a good LED for say $US1.50 for a 5 Watt unit - maybe cheaper. So LEDs alone would cost say $12 at the factory door or a retail cost of say 4x to 5x = say $50. Add support gear and that is liable to be hundreds and you are back into HID bulb cost area roughly. BUT that's not a tiny die size. You need to mount these so they constitute a point source comparable to a HID so ideally you'd pt those in a package yourself. If not (mot f us have problems packaging LED dies ourselves) and you wanted to mount them using available LEDs you'd probably be lucky to get under 3mm x 3mm LED positioning or for 9 in a 3x square say 9mm x 9mm. That's larger than a HID arc so the optics would not work so you are up for new custom optics to make a small linear (parallel beam) light source - a not modest lensing requirement. As well as "just doing it issues" you need high CRI (maybe mixed phosphors and special LEDs), good colour temperatures (links with CRI), drive electronics and more. You now have to cool it. LEDs cost$ (as above) a moderately large amount and yu want reasonable longevity. Say you opt for heatsink temperature of 50C. You need this in a housing that raises ambient and you want to be able to run this in Phoenix or Sammerkand or Nairobi in summer (maybe not Stovepipe Wells) without trashing the lamp. Say a modest 30C ambient. So delta t on heatink is 50-30= 20 C. So heatsink need is 20 C / 40 Watt = 0.5 C/W. That's a VERY nice heatsink, unless you have to pay for it. You'll certainly want to go to some lengths to stop hot spotting near the heat source. Heat pipe quite possible. Mere liquid cooling to a secondary air cool possibly. Blown air in volume certainly as well or alone.
Stop!
This is getting hard. There is a risk of these being ridiculously expensive and of having design issues and of overheating and breaking. Sounds familiar, no?
ie this is a demanding task. It can be done with existing state of the art LEDs and state of the art cooling and worse - but HID does a nice job and people are paying for them unhappily but as required. So it's a technology whose idea has just about come. Expect to see the great and capable Philips Gloeilampen Fabriken company who lost their way somewhat since starting 100+ years ago but who have now returned to being masters of their original field, come up with something suitable any year now. (They will label it Luxeon / Lumileds.). Cree will be there. Also Osram. Soon also Seoul semi. Nichia maybe (they can afford to live off the patents from the rest). HP under another name. Maybe Siemens under another name. And others.
The chances of you successfully joining them with a cost competitive trouble free product at this stage is low.
Double Flying Horse brand will be there but the LEDs will fail very early, colour temperatures will be suspect, die matching marginal, actual light output down, unforeseen technical problems excessive. You can buy them now.