8mm Forum: Use 86v lamp to replace 110v lamp?

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Posted by Randall McGehee (Member # 5980) on July 31, 2017, 10:47 AM:

I have access to many 86v lamps and want to use one in a socket that had a 110v bulb. I understand that lower potential difference will cause more current to flow thru the bulb, making it burn brightly. But will it shorten the life of the 86v bulb so much as to make it not worth the conversion effort? Will it hurt the projector by allowing more current to pass through bulb circuit than designed?

Posted by Steve Klare (Member # 12) on July 31, 2017, 10:59 AM:

It'll be pretty bad for the lamp: the power in the lamp goes up with the square of the voltage, so if it's meant to deliver the rated wattage at 86 it will now be producing (110)squared/(86)squared times the rated, or 12100/7396 or 1.64 times the power it was meant for. If you got 5 minutes out of the bulb that sounds like a lot.

(Given enough excess power, EVERYTHING becomes a flash bulb!)

Whether it was bad for the projector depends on what it was rated for in the first place. Let's say all things are equal and it's a 86V, 100W bulb in a 110V, 100 Watt socket. You'd now be pushing 164 watts into a slot meant for 100 Watts: lots more heat and current. It might be a horse race which fails first, the bulb or the projector (hopefully just a fuse.)

If it started as a 50 Watt rated bulb you'd now be at 82 Watts: the bulb would blow first for sure!

I'm curious: what uses an 86V bulb?

Posted by Randall McGehee (Member # 5980) on July 31, 2017, 11:21 AM:

Ok that makes sense. Sounds like its not worth the trouble. I work in a school district and these "Wiki AV/Photo Lamp" EYB-5 86v bulbs I'm pretty sure went into overhead projectors

Posted by Richard C Patchett (Member # 974) on July 31, 2017, 01:18 PM:

Greetings
EYB/5 bulb. Cross Reference: Industry (JCD82V-360WS), Ushio (1000443), Philips (23972-3), Osram Sylvania (54448). Technical note: Operating this 86V bulb in an 82V socket will result in longer bulb life (175%) and reduced light output (13%).

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