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Old 09-24-2012, 07:47 PM
Jeff Jeff is offline
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Default Fun with the MD24 and percussion instruments

I've posted about the upcoming Halloween performance before.

Another part of the MIDI robot band are the Percussion instruments.
All driven by the MD24 decoder. Two MD24's are used in this application, and both have been programmed with the 1.4b fixed note length software. The MD24 driving the bass drum shown below operates using a shorter pulse timing than the others, and so has a separate MD24, since the fixed timing affects all outputs.
The note output from the MD24 is fed directly to an optically isolated, solid state relay (triac). The triac switches the 120vac line voltage to a surplus laundry solenoid, linked by a chain to the drum mallet.

The second MD24 has been configured with a longer fixed note pulse length, and commands five different percussion instruments.
The outputs of the MD24 are driving TIP122 Darlington transistors, using the circuit drawing available for download here on the forum.
Each transistor switches 12vdc provided by a power supply, to five different automotive door lock motors.
In the high hat, two motors are arranged in parallel to provide additional force.
The others are a Crash Cymbal, Snare (two separate motors), and a floor tom.

There was latency in each instrument because of the mechanism involved.
It was overcome by simply advancing the note timing in the application I used.

I posted a youtube video of the instruments performing an intermission track, as MIDI sequence data overlay onto a MP3 file.
Please pardon the poor sound quality. It was hastily recorded with a cell phone.
http://youtu.be/N8fs86rdQ-4

Jeff













Last edited by Jeff; 09-24-2012 at 07:55 PM. Reason: dang typos
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Old 10-08-2012, 06:16 PM
Jeff Jeff is offline
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Saturday was spent doing hardware and sound checks on the various percussion instruments and the twin 7ft tall Tesla Coils.

Here's a link to a daytime video of "This is Halloween":

http://youtu.be/Nz1sxjP_XB0


And a night time video of those same instruments, and the Tesla Coils performing "Secrets":

http://youtu.be/SLAAlHcpYNw

We'll be using professional recording equipment/people on Halloween night.
Sorry about the shaky videos and overdriven microphones.

Regards, Jeff
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Old 10-11-2012, 06:37 PM
J.D. J.D. is offline
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That is slick!

Did you design all the linkages for the drum sticks? They're impressively powerful compared to other robot drummers we've seen. I'd love to hear any tips you came up with.

What about ghostly figures standing behind the instruments projected on fog?
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Old 10-12-2012, 02:13 PM
Jeff Jeff is offline
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Quote:
Originally Posted by J.D. View Post
That is slick!

Did you design all the linkages for the drum sticks? They're impressively powerful compared to other robot drummers we've seen. I'd love to hear any tips you came up with.

What about ghostly figures standing behind the instruments projected on fog?
Thanks!
I'm fortunate to have a machine shop. The first post has a link to the motors/solenoid used.
I tried to keep it simple with stock extrusions; both the support and the stick gripper are available from the big box home stores. The pivot points include brass sleeve bearings to eliminate any slop or squeaking. I split one of the crash cymbal sticks early on. The replacement was quick and easy with just one thumb screw holding it.

Great idea on the figures!
We have been playing with a 2000 lumen LCD projector, throwing at a 60 degree incidence angle to a wall of 6ft H x 20ft W clear shrink wrap fronting the line of instruments. Same as the Haunted Mansion ballroom trick. It looks ~OK, but needs more work. Distant street lights expose the trick when a moderate breeze comes up.
The fog machine would be nice. The wind issue keeps it from building very well.

Regards, Jeff
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Old 10-17-2012, 06:25 PM
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John John is offline
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Jeff, thank you for the updates! I hope you'll post the videos from Halloween as well.
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Old 10-27-2012, 02:07 PM
captofchaos captofchaos is offline
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Default Industrial Scale MIDI Percussion

I also have been thinking way too much about adding some percussion to my ensemble. Ive been toying around with using pneumatic hammers and a 30 yard roll of dumpster. Any thoughts.
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Old 03-05-2013, 05:17 PM
Jeff Jeff is offline
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Just an update to demonstrate the MD24 by controlling sixteen various percussion instruments. Simply using the solenoid driver circuit diagram John has posted here in the forum. A 12vdc 30 amp power supply provides the energy needed by everything.
Rather than solenoids, the drums and cymbals use 12v automotive door lock motors. The DC motor drives a nylon rack mechanism, linked to the drumsticks. These can be purchased online through many vendors.

This MD24 has been configured as "fixed-pulse-length note output" and assigned to the standard MIDI drum channel map. The percussion track has been advanced 80ms to compensate for mechanical latency.
Two kick drums. Snare. Low, Medium, High Toms. Crash, Splash, Ride, Chinese, & Bell Cymbals. Tambourine. Maracas. Cigar box. Cowbell.

I've included an equipment test video taken on Saturday prior to a public performance of Tesla Coil music that evening.

http://youtu.be/gL7qMiRBRNs

Other videos on this youtube channel include evening Tesla Coil performances backed by the percussion and robot vibraphone.

I hope you enjoy them.

Regards, Jeff




Last edited by Jeff; 03-14-2013 at 04:37 PM. Reason: link revised
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