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Thread: Servo's Revisited

  1. #1
    Join Date
    Apr 2010
    Location
    Grand Rapids, Mi
    Posts
    2,538

    Default Servo's Revisited

    After setting up and using a solenoid based scan through system using 70V noids and driver card. It was mentioned in the thread the use of servos for scan thru and other functions. I was a leery of this as it just didn't seem like it could work fast enough. I found quite different.

    Dave volunteered to send me a DMX servo controller he had made, so I started doing some research and talking with the local RC guys.

    Well first I became to impatient to wait for the toys to arrive to play (from Dave), and second was thinking of a TTL solution also to replace some functions and the fact that most of my stuff is TTL anyhow.

    I ordered a Pololu Maestro http://www.pololu.com/catalog/category/102 , quickly wrote some script (well about an hour worth my coding skills are slipping) to program the board for I/O and servo in/out button press movement. I used some ultra fast mini servos 90 degree's in .05seconds. Flagged them up and then added mirror or grating.

    Conclusion for me is this is a ultra cheap method for gratings and effects Dimple tubes, wheels, globes etc. The positioning to the eye, for the effects was perfect. I'll do beams repeat-ability on straight beams with a spot later on where it has been mentioned these fail, but that isn't my use. This simple controller and servo's one could save easily $1000 on an effects rail compared to using the traditional GM20's and drivers.

    I know if/when I have a GM20 or more likely an old step-mot8 fail i'll be hanging a robot servo in its place.

    Looking forward to testing and using the DMX board for servo control once it arrives. I only have 32 TTL lines for control out of LSX, and only 4 spares right now which will be taken up by my second head scan thru, so DMX will be my future to adding more stuff

    Tried to take a video, but the action is so fast I couldn't capture it well. I'll try more later this weekend and two servos are in line right with the solenoids so you can see them act side by side. Ah how nice 5 scan thru effects are on the galvo head
    leading in trailing technology

  2. #2
    Join Date
    Oct 2007
    Location
    Wisconsin
    Posts
    305

    Default

    I used RC servos in one of my earlier projectors, for x/y I had one servo on top of another with one mirror mounted on it.
    For drive signals I sent PWM signals out the joystick ports on an Atari 800
    I was deflecting a HeNe..!
    I had seen an article in a magazine, probably popular electronics where they were doing a similar thing with a Comodore 64, so I went ahead and did something similar. I had written software that I could use the joystick to steer the beam all over my apartment (the deflection was huge!) and I pressed the trigger button to store points in memory to play from, it was pretty fast! I had bought some $80 each servos, the fastest I could find at a local hobby shop.
    I picked up 4 tiny little RC servos on ebay a few weeks ago and hope to put them to use.

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