Enlarger transformer

alienlie · Aug 31, 2008

Hi. One question. An enlarger only works with a transformer or i can plug it in directly to the power source? I want to buy one from e-bay but i dont undrestand why some of them have transformers and some dont. Thanks

haris · Aug 31, 2008

Thing is: If you for example use ordinary b/w head for enlarger which use light bulb that works on 220V/50Hz, then you don't need transformer.

If you use for example colour or multicontrast head for enlarger which use bulb that works on 12V, then you need transformer to lower 220V from your wall electric outlet to 12V needed for that bulb.

Or, if you use enlarger that works with any bulb that need voltage which is different from your electric power source (usually wall electric outlet) you need transformer to transform your electric power voltage to voltage needed for that bulb.

I hope I wrote this in a way you can understand me, I have tendancy to write complicated about simple things

So, if bulb for enlarger use voltage, frequency or needs more ampers that is different from what your electric power source can to give, you need aparatus for adjusting your electric power cource to bulb's needs. If bulb use voltage, frequency and needs ampers your electric power source can to give to that bulb, you don't need anything, you connect it directly to power source.

NOTE: I wrote about 220V because in Barcelona that voltage is used.

Good luck.

alienlie · Aug 31, 2008

Hi Haris. I understood your explanation perfectly. Many thanks!

haris · Aug 31, 2008

And, pay attention, bulb for ordinary b/w enlarger head that works on 220V/50Hz is not any bulb like those you use for your lamp fpr example. It is bulb made for enlarging heads, which give "beeter" light than ordinary house bulb. Usually those bulbs are of 75W, 100W, 150W, 200W. THey don't need transformer.

Colour heads and multicontrast heads usually use halogen bulbs which work on 12V/50Hz and usually are 75W to 100W. those bulbs do need transformer.

There are other light sources for enlargers like cold cathode heads, but I don't know anything about them, I hope someone other will tell you more about them...

nworth · Sep 1, 2008

Enlarging transformers come in two varieties: voltage stabilizing and step-down. Sometimes both functions are combined in a single unit. Many enlargers use bulbs that do not run on 120 volts (240 in Europe and Australia). 24, 12, and 80 volt lamps are common. You can not plug these into the line voltage; they will blow out. A step-down transformer is used to reduce the line voltage to a value suitable for the lamps. Some color enlargers use a voltage stabilizing transformer to give consistent results even when the line voltage varies. These may provide 110 (or 120 or 230) volts output, or they may be some other voltage depending on the needs of the enlarging lamps. If the enlarger itself and its lamps are designed to work on standard line voltage, you can bypass the voltage stabilizing transformer if your line voltage is reasonably steady. Otherwise, you need to use it to get the proper voltage for the lamps, fans, etc. If the enlarger runs on 120 volts and your line voltage is 240 volts, you can substitute a commonly available step-down isolation transformer (see an electronic parts distributor) for the special enlarger transformer.

AgX · Nov 5, 2019

nworth said:
Many enlargers use bulbs that do not run on 120 volts (240 in Europe and Australia).

In whole Europe the mains voltage is 230V (with only few regional exceptions)

Befor harmonising it typically was 220V with exception of the UK (and Ireland?) with 240V.

John51 · Nov 5, 2019

One reason that condensor enlargers need a specialised incandescent bulb is that household bulbs usually have manufacturer info on the glass, which can show up on the print.

AgX · Nov 5, 2019

Standard household bulbs are just matted, enlarger lamps got a milky overcoat (opalized).
Standard household lamps are rated for the mains voltage, enlarger lamps are overrated to get more light output.

mklw1954 · Nov 7, 2019

As mentioned by others the halogen lamp (used in color head dichroic enlargers) needs to operate at its rated voltage that is different from mains voltage; condenser enlargers, using an incandescent bulb, operate at mains voltage and do not require a transformer. Some dichroic color head enlargers have a separate transformer unit and some have it built in, so you need to look up the enlarger to determine if requires a separate unit. For example, my Minolta MOD3 and former Omega B22 with Chromega head had a separate transformer but my Omega C760 has it built in, no separate unit. It's important to know so you don't buy an enlarger that needs the separate transformer but the seller is not including it (they can be hard to find).

MattKing · Nov 7, 2019

And in at least one case - the Beseler 67 series, Beseler made different versions of the dichroic heads over time. Some had separate transformers, and some are like the current version, where the transformer is built in.
You have to be quite careful if you are buying used. I have two different dichroic heads for mine, they both have separate transformers, and the connectors between the heads and the transformers differ. One of them uses a regular household plug connector, which is an invitation to disaster, because if you plug that cord into the wall rather than the transformer, the bulb will blow.

Ian C · Nov 7, 2019

I don’t know of any dichroic-filtered color or VC head with a transformer in the head. Doing it that way would make the head prohibitively large and heavy.

Whenever a dichroic-filtered head uses an 82-volt lamp, you can be reasonably certain that the head contains a small, simple, and cheap half-wave rectifier & resistor power supply. The output to the lamp is DC, not AC.

The following discussion outlines the design and shows the components used for an Omega C700 dichroic lamphouse:

http://www.blogintrigue.com/2008/11/omega-c700c760-power-supply/

The current Beseler 67S lamphouse is such a design, which requires an 85-watt 82-volt ESJ lamp. Likewise, for the Beseler 23CIII dichroic lamphouse.

https://www.bhphotovideo.com/c/product/4547-REG/Beseler_6730_Dichro_67S_Solid_State.html

https://www.bhphotovideo.com/c/product/105703-REG/Beseler_8132_02_23CIII_Dichro_Color_Lamphouse.html

You'd need a separated voltage stabilizer for the AC line to the enlarger for accurate color work, but isn't needed for black and white printing.

AgX · Nov 7, 2019

mklw1954 said:
As mentioned by others the halogen lamp (used in color head dichroic enlargers) needs to operate at its rated voltage that is different from mains voltage; condenser enlargers, using an incandescent bulb, operate at mains voltage and do not require a transformer.

Halogen lamps are incandescent lamps. And incandescent lamps (plain or halogen) are available in mains and low voltage versions.

For optical reasons (smaller filamant) in condenser projectors low voltage halogen lamps are preferred.
For colour consistency in colour heads halogen lamps (often, but not necessarily low voltage) are preferred.

John51 · Nov 8, 2019

Ian C said:
I don’t know of any dichroic-filtered color or VC head with a transformer in the head. Doing it that way would make the head prohibitively large and heavy.

My Durst Modular dichroic has a linear 12v supply built into the head. If it dies, I'll use a psu from a desktop pc.

Enlarger transformer

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