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Sunday, May 29, 2016

••◊ Let There Be Light! (DIY LED light update)

I built up the first prototype bulb today on the DIY LED light project.  It was a complete pain because the LEDs have a thermal pad underneath the package and I had to use a heat gun on each one to solder them down.  At least all the LEDs are lit and working as intended.

The picture below shows the LEDs lit at 10% power.  If I crank them all the way up there's no way to take a picture without the rest of the electronics going completely to black.  I also haven't built any of the necessary heat sinks for the bulbs yet, so I'm hesitant to crank up the power to 100% for more than a few seconds.  In the final design there will be six bulbs, which should yield a useful amount of light for video.

The heat sink design is my next endeavor.  I've been learning mechanical CAD so I can do a proper CAM job and produce nice looking heat sinks.  The bulb design incorporates a digital thermometer so I can monitor the LED temperature.  Hopefully this weekend I'll get firmware for that feature up and running.

It's getting there SLOWLY, but slow is OK.  This is just a hobby project and I already have thoughts about version 2.

UPDATE : I have the thermometer running (woo hoo!).  The bulb gets hot pretty quick without a heat sink.

Tuesday, May 17, 2016

••◊ Another LED light update

This last week I've added a number of significant upgrades to my LED light project.  It now has a dedicated power supply and thermal management system.  The fan controller board just came in and I was able to build it up quickly.  Now I just have to add some code to get PWM control over the fans.

One nice thing is that I was able to find some affordable, almost silent fans.  Even with all four of them on at full blast there was barely a whisper.  The first ones I bought could compete with a lot of small kitchen electronic appliances; noise wise.  They had to go.

The power supply only handles up to 200W, but for my initial prototype purposes that shouldn't be an issue.  The LEDs I plan to use are fairly efficient.

After I have the fan firmware running, it's time to actually build the LED bulb.  This will take a little more effort since each bulb in the system will need a significant heat sink to keep the LEDs in their safe operating area.

More importantly...so far, no smoke!

EVENING UPDATE...  The fans are up and running with firmware.  That was quick!  All four fans are still very quiet at home and ramp up in speed nicely.  Now I'm going to be forced to actually work on the bulb design.

Monday, May 2, 2016

••◊ LED Light Update

The LED Light is slowly progressing.  I finally fired up actual LED's today at full power and blinded a few people in the office at lunch time.  It's been a good experience so far.  I've only destroyed one component and that was because of an incorrect solder job.

The photos below show both the system and the illuminated blue LED's.  I actually had to turn the exposure compensation down on the camera 2 stops just to take a picture, otherwise the lens would be completely flared out.

The next step is to make a "bulb", or multiple strings of LED's since each driver board can drive up to 8 strings of LEDs.  Depending on how I wire it I can have either an RGB light, or a remote phosphor "pump" (i.e. just a bunch of blue LED's with a phosphor panel in front of them).  If I designed my own custom LED panel I could also make a "white" LED array or a bi-color array.  It's all about firmware now.  At the moment I'm "recycling" from a stash of old scanner LED's that we had sitting around the office collecting dust - which makes things a bit less expensive for experimentation.

The cool thing is that I can also have up to seven driver boards.  That's 56 strings of high power LED's!  My end goal was to create a light in the 500W to 1kW range since most LED lights I deal with seem to be quite wimpy.  I want something I can use in a daylight lit room.  What you see below is just the very dim start of things to come.