View Full Version : Omegalite and inductive loads

8-Jun-2004, 12:52
I recently picked up an old Omegalite D2. I have an Omega CS 50 timer, one of the old "autoexposure" probe jobs (that I never use).

I understand that most electronic timers won't handle an inductive load ('ala transformers & ballasts) - but the Omegalite is a mere 35watts not like the more powerful Aristo/Zone VI.

Anyone using an Omegalite these days? If so, do you use an electronic timer or an analog? I hesitate to try it and burn out my otherwise good timer.


8-Jun-2004, 14:42
hi matto -

i have an omegalite for an e4. it isn't the square one ( that is always "0n" and with a shuttered lens ) but a round one. i repalced it with an aristo cold light head, but from what i have read you shouldn't really have any trouble hooking it up to your timer. harry taylor ( classic-enlargers.com) would be able to tell you for sure if you need any sort of special timers &C. he is a walking encyclopedia when it comes to omega enlargers :)

good luck!

- john

ronald moravec
8-Jun-2004, 16:09
I understand the high inductive loads will damage an electronic timer over time, not usually at first. Buy the Aristo contactor, save the timer. You may blow timer and have to buy a timer and contactor anyway.

Before spending any money, plug the head directly into the wall and make some prints using a cardboard shutter under the lens. Mine gave VERY uneven light distribution. I fixed it by taping aluminum foil to the inside half of the tube in an arc six inches long along the 4 inch side of the of the neg. No direct light from the tube hits the short end of the neg, but light is bounced from the outside for the tube against the housing and then illuminates the neg ( two strips required)

Just measured and the foil strips are 3/4 wide and 6 inches long. The beginning 1 1/2 inch and the last 1 1/2 inch of the 6 inch strip are wide enough to cover 1/2 the tube. The extra wide places cover the corner areas of the neg. The 3/4 wide cover the middle 3 inches of the total strip.

If you can`t understand, e mail me with a fax number and I`ll send you a diagram.

One final note, the foil is just taped to the tube with clear scotch tape. No heat is generated by the tube, so this is ok. Mine is an Omegalite D.

Jim Rice
8-Jun-2004, 18:54
The primary issues with iductive loads are the high inrush currents upon connection, and the counter emf generated upon disconnection. Both of these can be dealt with by one of the simplest of electro/mechanical devices, the relay. Get one with a coil designed for the output of the timer (presumably 120v ac) and contacts with a current rating vastly in excess of the specified current draw of the head, on the order of 10x. You want double pole contacts, so you can switch both the hot and neuteral legs, so a DPST would do it, though in practice a DPDT will be easier to find, and work just as well, just use the nomally open contacts. The relay coil itself is an inductive load, though of such low inductance as to be triffling. Put it all in a plastic box.

Alec Jones
8-Jun-2004, 21:36
It's the timers with digital displays that show the most sensitivity to excess voltages, I believe. I remember burning out my new Omega Digital Timer the first week I had it using a cold light head [about 25 yrs ago]. Omega fixed it gratis, but sent me a "sharply worded" note instructing me NOT to do THAT again! They suggested I use their E-99 timer [electronic but NO digital display] for that enlarger and it has worked perfectly ever since.

The newer digital timers may have protective circuitry now, but I would have to see it in their instructions before using that combination. As someone else said, it isn't the operating voltage, but rather the surge that "hurts".

9-Jun-2004, 01:35
The CS50 is "electronic" but does not have a digital display. So maybe it is not a problem? But I am concerned about the circuitry in the cds probe. Maybe i am not correct in calling this an "electronic" timer.....