Exposure Unit

[vassili]

Hello All,

fairly new to the world of LED chips I might need some help from some of the wizards here.
I'm a darkroom printer that wants to build a new exposure unit using UV LEDs as a point light source.

my setup would be a cube with 16x 100w chips, 2m away from my exposure plane, with: 4x 365nm + 12x 395nm
Regarding the circuit itself I would want to be able to switch to 3 positions: 365nm alone, 395nm alone, or both.

the LEDs I'm looking at are rated at 100w, 30-36 Forward Voltage, 3500mA tops
here for 365 https://www.lumixtar.com/100w-uv-365nm- ... r-led.html
here for 395 https://www.lumixtar.com/100w-uv-390nm- ... r-led.html

How would you guys go about this ?
Would mounting in series 4 LEDs to their dedicated driver make sense or is it overkill ?
I obviously need power for short exposure times but my understanding is also that the more power the more heat loss, such that running less mA % to the chip could sometimes be beneficial...

Regarding the rest of the system I'm looking at passive heatsinks with 2x fans for an airflow inside my cube and as an option a 10A auto-switch-off box after my exposures are completed (20mns tops for the longest exposures).

If one of you guys is excited to brainstorm with me, I could use the tips
Many thanks,
v

[Shimbob]

What's the total power you want to put down? 16x100W is an awful lot of UV. You're right that running them at lower power would improve efficiency & reliability.

The specs on those LEDs is woefully weak, hardly any voltage vs current data. Some assumptions might have to be made.

[vassili]

With the unit being at a 2/2.5m distance from the exposure plane to cover over 1m2,
something like 1000-1200µw/cm2 with the 4x 365nm chips, 2000-2400µw/cm2 with the 12x 395nm chips.
The two wavelength are meant for different needs, they won't run simultaneously.
Regarding the COB specs I requested a proper data sheet indeed.

[Shimbob]

Unless my math is terribly wrong, that ends up being 10-12W/m2 and 20-24W/m2, right?

[vassili]

Yes, that is correct.
Got the data sheet for both wavelength, looking pretty good no ?
Running 50% current would still gives me 80% luminous flux apparently.

[Japes]

Hello All,

fairly new to the world of LED chips I might need some help from some of the wizards here.
I'm a darkroom printer that wants to build a new exposure unit using UV LEDs as a point light source.........

If one of you guys is excited to brainstorm with me, I could use the tips
Many thanks,
v

The folks at Waveform/realUV™ seem to have a bit more info about their products. Maybe ask them a few questions.

https://store.waveformlighting.com/coll ... lood-light


https://www.waveformlighting.com/datasheets/CS_7022.pdf
https://www.waveformlighting.com/photom ... 022.95.pdf
https://www.waveformlighting.com/photom ... 022.65.pdf

[vassili]

Hey all, thanks for this.

Pushed my research and figured out I could run my 16x100w COBs at 50% power (3500mA > 1750mA)
with a better UV output than what 50w would give me.

Is it good to assume I only need 3 drivers in the end ? I was looking into the Meanwell HVGC series (C.C.).
I could have one for my 4x365nm Leds in series and 2 for 12x395nm Leds (2x 6 in series).

Many thanks for the help !