Wednesday, February 5, 2014


Again, MEMS stands for Micro Electro Mechanical Systems , which is a known science. MEMMIS is an acronym that I came up with to describe MEMS applications for Musical Instruments. These systems can be amplified acoustic, electromagnetic,optical, pneumatic, liquid, electrostatic, or any combination of these systems, both passive, active, and or chemical. What is primary in a MEMS application is that there is an electro-mechanical element present at a microscopic level. So before we can dismiss MEMS as a resource for musical instrument technology, as well as possible high fidelity applications, we must first gain a strong understanding of it's possible practical uses. I am concerned primarily with the science of Organ Tone Generation. As in:
- Acoustic Pipe Organs
- Tone Wheel generators [(macro) electro-mechanical/electro-magnetic] ie. Hammond organ 35'-75'
- 'Keyed' or 'Free' Reed Tone Generators [(macro) electro-mechanical/electrostatic] ie. Everett & Wurlitzer
- Purely Electronic Tone generators [  vacuum tube, transistor, various synthetic A&D] ALL manufactures

So we can now add MEMMIS to this list. This is the logical 'next step' in the science of organ making. One nice thing about beginning the technology with the organ is that since the dawn of the very first primitive pipe organ, man has always discovered a technology unrelated to organs and then implemented this technology into a more refined and better sounding organ. Just think back to the first time you heard these words together- ALLEN COMPUTER ORGAN. I was at a thrift store seeking records to add to my collection when I came across this title-

Allen Digital Computer Organ System 120 & 201 (Demonstration Lp Record)

I brought this record home after paying probably 90 cents ( the usual going rate for used LP's at the thrift), put it on the turn table, and in my usual routine I flipped the record sleeve over to read about what I was listening to...and noticed a date of 1973! My immediate reaction to hearing the organ was that this 'computer organ' must be computer controlled, but certainly not the tone generators! Well, I was wrong. Upon closer research I found that Rockwell approached Allen for a unique collaboration to using their new digital microprocessor integrated circuits as early as 1969! Rockwell wanted Allen to succeed with the 'Computer Organ' because it would represent a new pinnacle in high tech reliable digital performance that could be witnessed every Sunday by engineers world wide. The Allen MOS-1 organs sounded more like real pipe organs than anything sold up to that point that was not real pipes.  The model 100 was introduced in 1971 and the 120 & 201 in 1973. So this was a very advanced science finding it's way into the organ field. We can be sure that it took years for the average player to really understand what a digital organ was. 'Digital' was not a household word until around 1995 except for digital clocks and watches. So to talk about a digital organ was gibberish to most ears. 
   So what has MEMS to do with music? What did digital MOS circuits have to do with music in 1971?
Lets expand our minds and visualize the possibilities.

Have a look at the following abstract here - http://iopscience.iop.org/0960-1317/17/7/007/refs

A micro electromagnetic generator for vibration energy harvesting

"Vibration energy harvesting is receiving a considerable amount of interest as a means for powering wireless sensor nodes. This paper presents a small (component volume 0.1 cm3, practical volume 0.15 cm3) electromagnetic generator utilizing discrete components and optimized for a low ambient vibration level based upon real application data. The generator uses four magnets arranged on an etched cantilever with a wound coil located within the moving magnetic field. Magnet size and coil properties were optimized, with the final device producing 46 µW in a resistive load of 4 kΩ from just 0.59 m s−2 acceleration levels at its resonant frequency of 52 Hz. A voltage of 428 mVrms was obtained from the generator with a 2300 turn coil which has proved sufficient for subsequent rectification and voltage step-up circuitry. The generator delivers 30% of the power supplied from the environment to useful electrical power in the load. This generator compares very favourably with other demonstrated examples in the literature, both in terms of normalized power density and efficiency."
So that's all for today, see if you can get a few parallels to the operation of the Hammond Tone Wheel Generator and a smaller electromagnetic vibration energy harvesting device.

Feel free to ask questions, make comments, and offer ideas and concepts regarding MEMMIS.

-Paul Jacobs

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