8mm Forum: Projector motors....amp rating?

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Topic: Projector motors....amp rating?

Thomas Dafnides
Expert Film Handler

Posts: 247
From: St. Louis, Missouri USA
Registered: Dec 2009

posted February 01, 2013 07:41 PM

Does anyone know what amp range most 8mm projector motors are rated at? I am thinking about buying a variac to reduce my home line (125) voltage down to 115 which is what most projectors were built to run at 50 years ago.

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted February 01, 2013 10:46 PM

Both of my Elmos are fused at 3 Amps which means they really draw less than that, which also means if you get a transformer rated higher than that you should be fine.

If the motor is driven through a transformer it's the current into the plug you really worry about.

I would imagine (for example) GS-Xenon will draw that and more. You might want to take that into consideration.

What's your concern Thomas: Lamp life? Circuit life?

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All I ask is a wide screen and a projector to light her by...

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Thomas Dafnides
Expert Film Handler

Posts: 247
From: St. Louis, Missouri USA
Registered: Dec 2009

posted February 02, 2013 08:51 PM

With the rising price of bulbs...my main concern is lamp life, plus a cooler running projector..will be a longer lived projector .
I was on a stereo forum and the guys with the 60's electronics recommend using the variac if your household voltage is 125.

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted February 02, 2013 09:06 PM

I just measured my own line: 118.5VAC.

Then again that's 118.5 on a cold winter night when the entire neighborhood isn't running air conditioning and the businesses are closed. I bet it's on the high side of normal around here.

Have you actually measured yours? 125VAC is pretty high for US house current.

A lot of modern electronics is designed for anything between 85 and 264VAC (Worldwide usage) and doesn't care a bit as long as you stay in that range. The old stuff is touchier about the voltage though.

Variacs are pretty expensive new (I bet you can luck out used, though).

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All I ask is a wide screen and a projector to light her by...

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Thomas Dafnides
Expert Film Handler

Posts: 247
From: St. Louis, Missouri USA
Registered: Dec 2009

posted February 04, 2013 06:47 PM

I deduced the voltage simply by observing one of my projectors that has a multi-voltage transformer....the lamphouse remained warm at 125v setting but at 117v it became HOT to touch. When I called my utitility company, they could not give me a definitive reply but simply, "it varies house to house".

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted February 04, 2013 07:44 PM

I understand your logic, but it's possible it's OK for the lamphouse to get that hot. You need some numbers!

You can get fairly cheap multimeters that will help you decide if you have a line voltage problem, like this one:

At The Shack!

(Needs a Battery)

The other thing is if you decide to go the variac route you really need a meter to set the output voltage, otherwise it's a shot in the dark.

I had a Radio Shack multimeter about ten years and it served me very well. When it went wherever dead electronic test equipment goes I found a used example of a Fluke multimeter I really liked using at work as an upgrade on E-bay. That's chancy though: these take an awful beating in the hands of people they should never be placed in and can show up as useless as a rock with test leads!

I have meters stashed all over the place including some cheapies in the cars. Knowing whether your battery is dead or perhaps the alternator makes a big difference out in the middle of nowhere!

To me a meter is kind of indispensible. Then again I don't think people should be allowed to drive until they get at least a "B" in physics, so I guess I don't speak for everyone!

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All I ask is a wide screen and a projector to light her by...

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Thomas Dafnides
Expert Film Handler

Posts: 247
From: St. Louis, Missouri USA
Registered: Dec 2009

posted February 05, 2013 06:28 PM

Steve,
I appreciate your input into this. Thanx.

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