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Thread: Inexpensive External Interface is Working

  1. #1

    Default Inexpensive External Interface is Working

    Happy Thanksgiving!

    I rushed home and hacked together an optically-isolated interface for the HR16-RGB "Lumidrive" RGB light engines. The three channels are isolated from the Procyon so as to prevent damage to the unit.

    I was looking around at my parts on hand and realized that I could make a constant-current driver using a cheap LM317 adjustable voltage regulator. The transient response seems fast enough, and I drove it with a P-FET that inverts the optocoupler output.

    Anyway, I'm only putting about 120 mA into each channel, but even without heatsinks, the LM317's are running so cool that I can still touch them without burning myself. I'm thrilled, as the colors that are shined directly on the ceiling are absolutely breathtaking.

    I'm going to enjoy a night session before bed with open eyes (I wouldn't even think of looking at the high-power light!). FYI, the LEDs in the fixture are 1W luxeon, one each of R, G, B. The nice thing is that the light engine already has heat sinks in place for the LEDs and a lens over the whole unit. Worth the price of admission--I can't wait to get you guys a schematic and photos/videos!

    See you soon,
    --Scott

    Addendum: The brightness control on the Procyon works in its full range, and controlling the lamp from the Procyon software works great. I can program ganzfeld colors, etc. with almost the exact stated resolution. For this configuration, the starting values for each LED is 129 instead of 128.
    Last edited by electronguy; 11-27-2008 at 07:32 PM. Reason: addendum

  2. #2
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    Default Re: Inexpensive External Interface is Working

    Congratulation, Scott, on a successful build!!!

    I shall look forward to seeing and hearing more about it.

    Cheers,
    Craig

  3. #3
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    Default Re: Inexpensive External Interface is Working

    Sounds really cool. Can't wait to see the details!

    -Andy.

  4. #4

    Default Re: Inexpensive External Interface is Working

    Okay, it's not the "prettiest" prototype I've built, but...

    The schematic is available at:

    http://ganz.blueelectronlabs.com/pro...nSchematic.pdf

    and the photo of the proto board and LEDs are at:



    If you want to change the current into the LEDs, change the 4 ohm resistor. The equation is R=1.2/I, where R is the resistor value to use and I is the current in amps. So, for 300 mA (0.3A), we use a 4 ohm resistor. For 200 mA (0.2A), use an 8 ohm resistor. Finally, for 100 mA, use a 12 ohm resistor.

    For power supply voltages much greater than the LED's forward voltage plus about 6V, the excess will be wasted in the LM317's. So, this is not the most "efficient" design, but it gets the job done. A 12V supply is what I'm using and am outputting about 200 mA into each LED.

    The result is much better than I originally expected--I get the strobing and color shifts but I also get to enjoy the wide range of colors. Also, I can close my eyes and dial in a yellow, for example, and feel like I'm outside on a nice autumn day...

    Enjoy,
    --Scott

  5. #5

    Default Re: Inexpensive External Interface is Working

    Great work, Scott! We built a few prototypes of a similar nature last year, using the Lamina Ceramics Titan RGB light engine:

    http://www.laminaceramics.com/Produc...ies/Titan.aspx

    This array packs over 1,000 lumens @1400ma into about one and a half square inches, which definitely needs a heat sink or fan. Once the project engineer for those prototypes finishes his home construction, maybe we could make a short production run--not cheap, though, since the arrays alone cost roughly $80.

    I like those Luxeon LEDs a lot--you probably know that they are also available in 3w and 5w versions, though the higher powered ones are less efficient in terms of lumens per watt. They also have some other color variants (like 'royal blue') which could expand the overall color range (how about a dual-Procyon driver?). Our original prototypes for the Procyon included a fourth, 'white' color channel, which produces nice pastel colors... unfortunately we added so many CPU intensive features that we had to drop that color before entering production.

    Thanks much for very generously posting your design info on our Forums, Scott! I hope it inspires others, or maybe you might be inspired to build up a batch for other users... because the 'full color eyes open' experience is the most compelling of all.

    -Robert

  6. #6

    Default Re: Inexpensive External Interface is Working

    Thanks for the info and support, everyone. Just finished finals and have been working on creating a robust interface that makes use of the highly efficient RECOM RCD-24-0.xxx DC-DC constant-current LED drivers.

    I am having odd difficulties interfacing the optocoupler outputs to the PWM control. The RECOM unit is specified at a PWM rate of 200 Hz and I do not know the specs of the Procyon--plus my oscilloscope recently died and I cannot check any waveforms.

    I got really good results with the linear interface. When I use the RECOM unit, I have specifically setup the analog dimming pin to create a maximum current that will flow in the LEDs for each channel. The spec. sheet for the RCD unit says that we can run the analog and PWM channels simultaneously--and it appears to work as advertised.

    The issue for the time being seems to be the output of the Procyon--it is a PWM controlled voltage that is to create a current in a nonlinear device. I put it into an IRLED via an optocoupler and things are great, but the output of the optocoupler is just a 100% reproduction of the input current. As such, it transmits the analog "current" that was available from the Procyon originally. Using this analog signal in the linear regulator circuit, I was able to turn the dimming control on the Procyon unit down and up and get proportional dimming. The PWM input on the RCD device is purely digital, with < 0.6V yielding full on and two states for off: <2.9V for off and >2.9V for standby.

    I am avoiding standby since I assume that the DC-DC converter will have a long startup delay, so I maintain the control voltage at about 2V for off and <0.6V for on. Another difficulty is the PWM and analog dimming control inputs of the DC-DC unit are specified to draw 1 mA maximum. This requirement instills some loading issues for the driving stage and simple resistor divider networks aren't necessarily the best choice.

    The last test I ran was to utilize a small red LED to limit the PWM voltage to <2V when the optocoupler was off and <0.6V when on. I noticed that the red LED would go through a "dimming" phase when I had the Procyon connected to the computer running various ganzfeld colors to do my dimming tests. Yet the output of the HL16 module provided virtually no dimming capability and the brightness controls on the Procyon unit have little effect.

    I will continue to try different variations for the PWM control but may ultimately use the analog dimming input of the DC-DC module which will be driven by a OTA-buffered optocoupler output (current mode).

    --Scott

  7. #7

    Default Re: Inexpensive External Interface is Working

    Happy holidays, everyone. I spent a bit of time trying to create a viable interface for the RECOM DC-DC converters but have decided that the PWM frequency of the Procyon is too high (or something) that is not giving good results.

    Please disregard any reference to the RCD-24-0.xxx units and stick to the linear schematic posted earlier if you are so inclined to drive an external interface--it worked great and I'm going back to it--I'll use the RCD-24's for other projects, just not the Procyon.

    Again, happy New Year and thanks for the suggestions and encouragement. I hope I didn't overwhelm anyone with the nitty gritty details of some of this. Instead, I'm going to put on the original Procyon glasses in a few minutes and nod off to a peaceful slumber...

    Still lovin' the Procyon,
    --Scott

  8. Default Re: Inexpensive External Interface is Working

    Hi Scott

    I was pointed to this thread by Andy. It sounds like you have invested a great deal of time into this project. I have been mulling over the possibilities of using the procyon as a controller but got suck at the first hurdle. I don't recognise the plug and socket arrangement used for the light frame connection, it's not one I've come across.

    Where do you cut into the procyon for your interface? Are you using the existing lightframe output socket on the top of the procyon? If so, do you have a pin out diagram and do you know where I can buy compatible plugs from, preferably on the net?

    What I would like to do is build a break-out box so that I can analyse the existing signals and consider the possibilities for controlling different room lighting arrangements combined with surround sound.

    I am reluctant to dismantle my procyon while it is stll under warrenty and you seem to be well down the path already so any information would be helpful.

    Kind regards
    Mark uk

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    Default Re: Inexpensive External Interface is Working


  10. #10

    Default Re: Inexpensive External Interface is Working

    Hi Mark,

    Andy beat me to the link! I purchased the connector from www.mindplace.com (I believe I e-mailed Janice (?) directly as they weren't available from the store at the time).

    I chose to buy the cable with the bare ends. There is a .jpg photo in the above thread that shows the connections--also, I have indicated these wire colors on my schematic pages).

    The connector seems to be a standard USB mini-B (different from a standard USB B connector), but I haven't confirmed. Since a cable from other suppliers may not have the same color coded wires, etc., I chose to buy from MindPlace--plus it kept the money in "the family"

    To answer your question about opening up the Procyon--I didn't do that and won't do that. Even though I'm an electrical engineer, the Procyon is just too expensive to hack--plus I can always make my own version.

    I used a digital multimeter to verify the connections of the cable--in particular to establish the polarity. The LEDs appear to be connected as a common anode (all the plus "+" sides are connected together) and the corresponding cathodes (the "-" sides) are connected to the corresponding driver wire.

    It's really cool having the Procyon as a signal generator with external lights--it really gives quite the boost to the color range.

    Happy New Year everyone; this will be a good year

    --Scott

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