New Hammond organ/Electromagnetically actuated piano hybrid instrument

AKA Magnetoharmonium.

The general idea behind instrument is to use current carrying strings (from brass likely) in magnetic field to acoustically generate sound, with signal being produced by modified digital Hammond Organ emulation (or in transistor, analog way, doesn’t matter at this moment) then routed to correct strings (via demuxer system) and amplified before each string.

Whole idea came to me long time ago, but now I need help with making it in real life. So, I’m starting with two prototypes, one based on zither and using electromagnets driving each string, the other one with one or two strings and using actual Lorentz force actuation - I already could find other instruments which use the electromagnet technique, like segulharpa or magnetic resonator piano - which is why I want to begin with this technique on larger scale, as some know-how is already available, while for Lorentz force version there is almost none.

So, I already designed this diagram of instrument prototype using modified zither, but I’d need a lot of help to start making it finally. Anyone’s interested or willing to?


this sounds similar to what you are building


Take a look at the korg painet-t mechanics.
Id be happy to assist in any way i can.

Edit: Hohner not Korg


Yeah, it has some similar ideas behind it, but also is vastly different in many areas.
But I saw that one already, though it wasn’t inspiration at all.

Thanks for reply and suggestion anyway.

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It’s sort of electric piano in reverse, where electric signal comes first, and string vibration later. Still, final version probably will have some things in common.

EDIT: main problem at this point is learning both analog and digital electronics (DACs and ADCs, amplifiers, demuxers, DSP, PCB design etc.), as well as getting better understanding of electromagnets and electrodynamics (which is one of my college courses anyway). So, if someone would like to help with understanding any of these topics, I’d be more than thankful.

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I know these things have been electrified and your project made me think of them.

-Fumu / Esopus


I think I saw that thing once…

Nice nickname btw

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I have an almost identical model!
Added a drone mute, a key weight as a capo and a sofar failed attempt at adding a wheel, hurdy-gurdy style. Changing/improving the fretting position and surface contact. It’s a long list but it’s on the list.


It’s a tribute to the Kosmo 2.0 of sorts… I joined the LMNC Discourse while my mind would develop a premise where the VCO had link ports hence could join to be a massive hive mind (powered by Arduino.) It makes absolute no sense because the link ports and the Arduino are electronically separated by the circuit. :rofl:

-Fumu / Esopus

OK, now I need help with those:

  • where to find cheap, good electromagnets in large quantities, or any other necessary parts, like amplifiers ig - this is mostly bcs our budgets are really tight and e.g strong electromegnets in large quantities can cost like hundreds of PLN or even hundreds of dollars
  • designing PCB for both prototypes (EM-driven and Lorentz force-driven)
  • learning DSP
  • learning how to properly design power and OTA amplifiers
  • calculations and simulations regarding electromagnetic, electronic, mechanical, thermal and other parameters, especially for LF actuation - me and my copartner found out open-source software for this, which are FreeCAD and ElmerFEM

Any help or reccomendations?

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So, any ideas on it @Farabide ?

Hi, my apologies, i am not always able to contribute.
For cheap electro magnets, i strongly suggest you experiment with making your own. Once you have the sound you want; turns, copper diameter, core and magnet and then, if need be, you have a spec to follow before shelling out for a factory made coil.
As for the pcb, start with a circuit diagram for each.
Me id then breadboard or scratch build on veroboard before i can verify the circuit. I use easyeda myself.
As for amps; id start with OTA but you could also use an audio transformer as a passive amplifier.
Again, my apologies, I hope this is a useful reply.


Thanks, will consider this.

Ok, so there is entire documentation for READY pcb for most of the electronics here, I based my design around it:

And someone send me this link, but it’s not meant for sharing for public

There has been a little bit of success yesterday in building Lorentz Force actuated version of the instrument:

Resistors used for impedance matching

Amperage through string when on and off.

I managed to make reasonable current go through strings after many attempts. Still, there wasn’t any sound due to low magnetic fields achieved (I only got terrible power supply at that moment, so I couldn’t power electromagnets properly). Also, the place was a bit noisy. Those are possible reasons I can think of.

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OK, I can finally write some update on it, after few months:

I figured out how to build functional prototype - I’m gonna use several key parts on pic rel - old guitar with brass or copper strings, neodymium magnet on top of strings, repurposed amplifier, ancient-ass WYSE Cx0 thin client with adequate software and Arduino enhanced toy keyboard as a MIDI controller. I already experimented for some time with the guitar and amp itself, without audible results though. I’d need to properly calculate and estimate present electrodynamic and acoustic parameters, which I’m gonna do as soon as I re-learn what I had in college.

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