8mm Forum: Upgrading projector bulbs ....

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Posted by Osi Osgood (Member # 424) on February 21, 2008, 09:54 AM:

My post on David Pannell's topic brought up a good topic that I've needed help on for awhile.

I am just about out of my supply of 12 volt 100 watts (or is it the other way around? 12 watts 100 volts?), and I have been annoyed that they are not quite as bright as I'd like them to be.

The question is, if my projector is listed as 12volts 100watts, if I buy 12volt 150watt or 125watt, will they work on my projector,

and

... will the lamps be any brighter on my projector?

I thank you for your time.

OSI

Posted by Paul Adsett (Member # 25) on February 21, 2008, 10:55 AM:

Do NOT go there Osi! Putting a higher wattage bulb into ANY projector stands a good chance of a) overheating and physically damaging the projector and b) wiping out the projectors transformer.

Posted by David Pannell (Member # 300) on February 21, 2008, 11:19 AM:

Many variables here, Osi.

Paul is right.

It's not for the feint-hearted among us and mods like this are really for the very technically minded. If you feel you're up to it, have a go, but I cannot stress strongly enough that such mods are fraught with far reaching implications. I have given a brief synopsis below of what some of the essential things are to look out for. If you feel the least bit nervous in tackling a project like this, and it IS a major project, - don't even think about it.

Firstly you have to be sure that the transformer in your projector is capable of supplying the extra current (in terms of amps) of a brighter lamp. The current is the all important factor and is arrived at by dividing the watts by the volts. Therefore a 12 volt, 100 watt lamp will need 8.3 amps to power it. A 12 volt, 125 watt lamp will need 10.4 amps to power it, and a 12 volt 150 watt lamp will need 12.5 amps to power it.

The transformer may or may not be able to supply this additional current, and if not, the lamp will be duller than the one you are currently using, because in an attempt to supply the extra current, the transformer voltage will reduce and it will and overheat. This is known as 'transformer regulation', and is the ratio of output voltage to current.

It is possible to find out if the transformer is capable of this, but you need a little electrical engineering 'know-how'. You will need to measure the voltage across the lamp terminals while the lamp is on. Do this first with the standard 100 watt lamp. The voltage should be pretty well exactly 12. If it is less than 12 volts, you need to REDUCE the mains voltage adjustment to the point where the lamp volts are 12 - with the lamp on. This is the lamp design and is most efficient when run at its rated voltage, or a tad higher, but no more than 12.5 volts. Conversely, if the lamp voltage is higher than this, then you need to INCREASE the mains voltage adjustment to the point where the lamp volts are 12.

Having done this, your 100 watt lamp is now running correctly. (You may find that it has been being underrun with less than 12 volts, and bringing the voltage up to 12 by the mains adjustment could well provide the additional illumination you are looking for).

You can now try a higher wattage lamp, still measuring the volts across the lamp terminals with the lamp on. If the voltage is more than half a volt LOWER than with the 100 watt lamp, forget it! Your transformer will become a molten mass of copper and iron in very short order.

You can experiment like this until you find the optimum lamp, but I wouldn't mind betting that the manufacturer has designed the system down to a price, and it is probably not capable of supplying any increase in load.

The next thing to consider is cooling. A higher wattage lamp will produce buckets more heat, so you will need to get rid of that additional heat somehow.

And as if all this isn't enough, the filament design and its position within the glass envelope of a higher wattage lamp could well be very different from the stock lamp, so all the optics could be out of alignment, with different focal lengths etc. etc.

However, if you are prepared to invest time and careful enthusiasm, consider a beefier transformer, a more powerful blower, and can align the optics correctly, - like others have done in the past, - you could be onto a winner.

Good luck!

Posted by Steve Klare (Member # 12) on February 21, 2008, 03:55 PM:

Tim Christian did a project where he upgraded a Eumig 810D to a 150W bulb from the 100W EFP it came with as stock. How he did it is he selected a higher voltage 150W bulb of similar geometry to the EFP. He placed an auxiliary transformer in series (and in phase) with the existing one's lamp winding and it worked out that the difference in power was a result of the additional voltage, so the current through the main transformer was about equal to what it had been as standard. Doing it this way meant that the auxiliary transformer only provided the extra power, and not the whole 150W it would have been if he just gave the bulb its own independent power source, so it was smaller. He put the new transformer in an enclosure the projector sat on, which included some extra cooling for the projector.

He connectorised everything so he could return the machine to normal at will: this was mostly for use at his local cine club. He had a number of video based skeptics there who he enjoyed showing a thing or two on a regular basis.

He reported that this setup allowed him to show R8 prints 6 feet across with nice, bright, sharp images.

Posted by Mark Todd (Member # 96) on February 21, 2008, 06:39 PM:

Hi Osi have you been using a xenophot bulb as they are 20% brighter than a usual 100 watters anyway so a decent jump to start with like 120watt also seem to last longer too, well worth a go and cheap enough.Slightly whiter light too. And no electrical concerns,
Best Mark.
PS maybe you use them anyway?

PPS a bit later/sent you a mail Osi.

Posted by David Kilderry (Member # 549) on February 22, 2008, 04:32 AM:

Osi, today there is a large variable in the light output of 100w lamps. The lowest quality are the junk units made mostly for disco lights - avaoid them as they are poorly aligned and not good in projectors.

As Mark mentions there are some good options still at 100w that will improve your light. Talk to a specialist lamp supplier or consult their web guides for the information on brighter lamps at 12v 100w.

David

Posted by Winbert Hutahaean (Member # 58) on February 22, 2008, 07:29 AM:

I have one Sylvania bulb and this is much whietr than any brand (Osram, Philips). Try this.

quote:
xenophot bulb as they are 20% brighter

Hi Mark regarding this, what brand is available? and is in the box mentioned about Xenophot things?

thanks,

Posted by Osi Osgood (Member # 424) on February 22, 2008, 11:13 AM:

Mark,

Is that EFP the kind of brighter 100 watt lamp you were talking about?

Posted by Mark Todd (Member # 96) on February 22, 2008, 02:12 PM:

Hi Osi you should have had a link by now with them really cheap your way, and yes they were the ones, I`d buy them all at that.
Best Mark.
PS Winbert The Xenophots are made by osram and a big improvement on the usual osram older ones.

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