Dimmer for Modern Enlarger Lamps (Model 2)

[AJ Edmondson]

Anyone have any experience with a dimmer for the Modern Enlarger Lamps Model 2 for Omega D Series enlargers. I tried contacting Cree LED Lighting with no response. There seem to be several independent dimmers which vary the pulse width but I can't find specific compatabilty with the Cree XP G LEDs. I would really like to reduce the light output in order to stay at 10-12 seconds and f8-11 (without resorting to nd filters).
Thanks... Joel

[J.B. Harlin]

You need a constant current driver. I have used these for driving multiple high power LEDs. . . the data sheet will give you more info. . . https://www.ledsupply.com/led-drivers/buckblock-dc-led-driver

[AJ Edmondson]

Thanks for the response J.B. but I haven't done any circuit analysis in over 50 years and now have to restrict myself to some sort of "plug and play" solution. I don't want to destroy my light source since Cree no longer makes the XP G series (the XP G2 has even more light output). With my old Aristo I just used a Variac but LEDs are pretty confusing to me with voltage, current and pulse width variables.
Joel

[LabRat]

Unlike a lamp, LED's don't dim in a linear fashion, so don't expect to just turn a knob to new brightness, and some LED's are non-dimmable, but there are options to research...

Sometimes something dumb like sandwiching 2 diffusers or different thicknesses or densities of white plex diffusers will cut light enough without resorting to ND gels (that can also work)...

Steve K

[AJ Edmondson]

Thanks Steve... I was sort of headed in that direction. I understand that LEDs don't dim in a linear fashion and am not looking at something that is continuously variable. According to the specs the Model 2 is comparable to 150 watts and I have always used 75 watts. According to Cree, the color temperature of the XP G LED stays pretty consistent so I thought there might be an "off-the-shelf" solution. At this point (after having spoken with a couple of tech reps from LED suppliers) I am moving towards your suggestion with diffusers.
Joel

[J.B. Harlin]

Yes you will have to do surgery on the unit to add dimming. The BuckBlock LED driver has to go between the power supply and the LEDs. Look into Rosco ND filters. . . they are inexpensive. . . but do fade over time and use. . .