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A project log for Blue Sky + Corrected spectrum White LED fixture

Fixing terrible spectrum (missing cyan&green) of generic white LEDs to get perfect flat spectrum and impression of blue sky in the room.

mikhail-svarichevskyMikhail Svarichevsky 08/17/2015 at 20:430 Comments

With new 490nm and 470nm LEDs I can finally proceed:

470nm LED came close to specs:

With 10x0.7A for Cyan LEDs step-up regulator is taking too much heat, so I had to add few extra radiators:

After fine-tuning current in the LED chains I've got the final spectra:

Finally there are no missing colors - this is something which could satisfy me. And "blue sky" effect is really nice. As we were mostly adding LEDs near to eye (and camera) maximum sensitivity, light feels much brighter than before (as well as photo exposures).

Is there a visible difference? Yes, but not looking at spectrum analyzer it is hard to show you on the RGB display with RGB camera. I have cyan shirt for example, and it's color is visibly different under new lighting - but making and comparing a photo won't show much - camera renders it bluish, while in reality it is slightly greenish (regular LED on the left, corrected LED on the right) :

Personally, I am more than satisfied by light itself and I like it much more than my older 100k lumen HID fixture.

Future plans:

This is not the end of the journey though - I ought to replace step-up converters with ballast resistors with a proper constant current ones and make it RF-controlled (nRF24LE01). I am going for nRF instead of hiped WiFi ESP8266 because I personally cannot tolerate wakeup latency.

Instead of using standalone constant-current ICs I am going to drive mosfets from uC PWM pins while monitoring current. As there are no fast current changes this should do the job with very simple schematic.

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