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Thread: The dmx card, first run

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    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
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    Default The dmx card, first run

    OK,

    As you know, all beamtables are DMX these days, because of Pangolin dropping TTL on the QM2000. So I needed to modify my projector off of TTL/Manual. My best friend has a expensive German designed DMX based beam table driver, but it tends to forget its channel assignments. I have one of the same boards, and while very nice, and oh so very expensive, its problematic, needs split power like a galvo amp, and the power opamps are 28$ to replace if you nuke a channel.

    Neither of us has any budget right now, he has a newborn and I'm unemployed. Nothing Northlight made quite fit the bill for what we need, and we wanted a few novel features. Specifically the deliberate LACK of features, plus socketed parts for quick repair, as we make my best friend wear a garlic necklace when troubleshooting. So I thought what the heck, if I can get three more people on board I can do a run of low cost PCBs and we can try it.

    So generation one is in the picture. It comes in two flavors, PWM TTL with filtering to make a 0-5V or 0-10V analog output. Flavor two is the same card with the analog parts left off and the code changed to just output on/off.

    There are 8 analog/ttl outputs, plus a spare TTL I'm working on coding to a master shutter.

    The first run of ten are spoken for, but I'm willing to do one additional run, with a few modifications to the board layout to get assembly time down and buffer the TTL. I'd offer a kit, but soldering 44 pin PLCCs with manual soldering gear is a art form. The next one will have resistor array packages instead of discrete resistors.

    Features:

    All signals except the DMX input are brought out on one DB 25. The DB25 is not installed, so you can hand solder wires if you so choose. This is done so compact projectors are not limited to a few card locations. This makes it field swappable, two standard connectors and your done.

    Bracketing LEDs. Channel 1 and channel 8 are connected to led drivers, so when setting up, you have a quick way of knowing your addressed correctly. One other led lights whenever the DMX signal changes. A fourth led indicates addressing or wiring errors.There is of course a power led.

    Stackable, it has simple dip switch addressing for changing the start address.

    It has 10 mA of output drive on the analog channels.

    Socketed IO parts.

    Simple. No fancy setup and no offset trim etc.

    Downsides:

    Its a bit big, Its ugly, and not silk screened. The IO is not optoisolated.
    It is of course 8 bits like all simple DMX devices.

    PIC
    Click image for larger version. 

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    Coming soon, the matching actuator driver board.

    If there is enough interest, I will bring up the thread in the group buy section

    Steve
    Last edited by mixedgas; 07-27-2010 at 14:03.
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