Robotic Drums - Driving Solenoid from MIDI

Discussion in 'The Projects Forum' started by lholze, Apr 9, 2009.

  1. lholze

    Thread Starter New Member

    Apr 9, 2009
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    I'm trying to find the correct components to drive fairly powerful solenoids (click for solenoid specs), and trigger them from MIDI messages. My idea was to use this lighting controller (click for controller) , run the AC output through a rectifier and send that on to the solenoid. But the lighting controller is only to be used with resistive loads. I don't know if I can get around this with a snubber or not. There are a multitude of boards and kits for decoding MIDI and tripping relays, but I can't seem to find a set of components for safely driving a solenoid of this size.
    :confused:
    Thanks
     
  2. Bernard

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    Aug 7, 2008
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    Sounds interesting. What repitation rate do you expect, and how much volume variation is needed?
     
  3. lholze

    Thread Starter New Member

    Apr 9, 2009
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    The goal is to match the speed and dynamics of a real drummer. That means that two consecutive notes might be as close as 50 ms apart, but there wouldn't be a long series that were that close together. Overall, the average duty cycle would be pretty low: 2-4 times/second on something that gets used often like the hi-hat, but there could be "flurries". As for dynamics, a real drummer can go from very soft to very loud, but very soft is unusual in rock, so that would be a secondary goal. MIDI allows for 128 volume levels, which would be ideal, but I think quarter of that (32 levels) is fine, as long as there is sufficient range.

    Thanks
     
  4. bertus

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    Apr 5, 2008
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  5. Bernard

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    I used a Ledex rotary solenoid early'70's, to dial a rotary dial telephone, but could'nt find it in my junk box, just wanted to get re-aquanted with it. Look in on kiel long Chat for electro-magnet drive, similar.
     
  6. Bernard

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    'found Ledex solenoid and mounted it on a "drum". Beats soft, and beats loud, have not tested for max rep. rate yet, looks good so far, around 20 beats/sec. Presently using capactive discharge, 200μF, soft; 2200μF loud.
    Ledex nos. 810-362-330, could find no inf. but someone has one in stock. About 35mm dia. 20mm thick , might be smaller than yours, but something to work with.; also 17Ω. Drum # 10 can.drum stick,100mm mounted to armature with 3 2-56 screws.
     
  7. Bernard

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    Problem: control sound level by varing pulse width. Connected up 555 to give 5ms-100ms & rep. of 30 pps- .5pps. 555 drives a C2810 , 700V, 12A transistor. verry little difference in sound from just enough pulse width to strike drum to keep stick in contact with drum. Next trial will vary ??, already tried varing current with variable series resistors, poor control.
     
  8. Bernard

    AAC Fanatic!

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    Last reply. Here is an outline for a binary controlled sound level, solenoid driver. Values to be adjusted to fit solenoid used. For large value caps. it may be necessary to use an active discharge to keep rep. rate up, ie another set of MOSFETS.
     
  9. mik3

    Senior Member

    Feb 4, 2008
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    Some students made drums by using compressed air pistons and they work fine. Think of it.
     
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