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Previous post in this blog sequence:

Kitchen Lighting System Phase 2


One of my goals for this project was to increase the light output of the LED pucks.  I do plan to create some new lens, but first I wanted to look in the effects of using a collimator to direct as much of the light up through the lens.  I had started to play with this concept a while back, using a very simple design.


simple collimator - 1simple collimator - 2

Here is my first attempt.  These were made of 3/4" PVC piping, cut down to the proper height, with a reflective mylar film placed inside the pipe (note: the PCB has 4 vias, with 30 gauge wire sections soldered in, placed around the inside diameter of the PVC pipe to help hold the unit in place until the PCB is attached to the housing).  The addition of this simple collimator did increase the light output by ~20% with the diffuser in place (974 Lux @ 10" after, compared to 804 Lux @ 10" before).  While I like the simplicity of this solution, I did create this prior to owning a 3D printer, so I thought I would try an update, attempting to improve the design with a simple cone-like collimator.


new collimator - 1new collimator - 2

While the new collimator did increase the light output without the diffuser by ~5% of the simpler collimator, with the diffuser in place there was measurable change.  This must be due to the topside inside diameter of the collimator is actually larger than the diameter of the opening below the diffuser, so I believe that the added light output was attenuated by the aperture effect of the diffuser opening.  In the future, with a designed housing, I hope to work a little more on the collimator design, increasing both the slope and the inside diameter of the collimator and diffuser opening.


In addition to my attempts to increase the light output of the pucks, I also did a little work on my overall plan.  Initially, I had thought that I would use the 915 MHz version of RFM69HCW transceiver as my communication link (as I had a few of these left over from a job I have been doing for a client), but I have instead decided to switch over to some EnOcean 902 MHz parts.  I have used the EnOcean parts on a commercial lighting product in the past, so I decided to attempt to leverage my design by using some existing products, instead of creating my own versions of something very similar.  I have ordered the Sensor Kit - 902 (https://www.newark.com/enocean/sensor-kit-902/radio-module-raspberry-pi-902mhz/dp/33X0509), to provide some potential sensors and to allow me to reacquaint myself to with the EnOcean message formats.  I already have the EnOcean USB 300 Gateway dongle, so I should be able to quickly start viewing message packets and further define some of the communications for my design.


Here is a sketch of the system layout and communications for this project:


system layoutsystem layout key


Thanks for reading!