[sdiy] Magnetic String Actuation

[ulfur hansson]

you can also run current (signal) through the string itself - and place magnets close to thw string - be careful not to zap yourself though by accidentally touching the strings, also make sure the string gauge is heavy enough to handle the current :)

sent from outer space

> On 13 Sep 2022, at 09:06, René Schmitz <synth at schmitzbits.de> wrote:
> 
> On 13.09.2022 08:26, Spiros Makris via Synth-diy wrote:
>> Alright! Then it sounds like I'm on the right track since I got the cheapest electromagnets (2.5kg) I could find on aliexpress! I'm kinda itching to give this a go so I'll pay a visit to my local robotics shop and get another cheap one and give it a go sooner.
>> 
>> Harry that's useful, I'll try the middle of the string length for my next experiment. While you are right, I do think my tuning was good enough to warrant some sympathetic action. It's true that the sustainer configuration will probably produce vibration more easily, since it cuts out any problems with tuning.
> 
> I'm thinking, you should try to drive it at half the frequency of the natural frequency of the string, as with a simple plain electromagnet, and an non-magnetized string, the force is attractive regardless of the polarity of the current.
> 
> So you get two peaks of force per cycle when you drive it with a sine wave.
> 
> This is a <electroboom> full bridge rectifier </electroboom> action, which doubles the frequency.
> 
> 
>> My goal is to create a sympathetic string bank and excite it with sound from synthesizers or other electric instruments (ie guitars, lutes etc). This effect is most common on instruments like the sitar, but all stringed instruments have some sympathetic effect going between the strings while you play them
>>  I expect that by adding the right amount of positive feedback I can get a sort of sustain control, and self-oscillation when cranked up. My assumption here is that the actuator, string, amplifier and pickup essentially form an oscillator, with the string acting as a high Q resonator, akin to an LC tank.
> 
> 
> An Ebow has a magnetic bias in the form of a pre-magnetized core (both in the pickup and the transducer),
> 
> so that they can use the same frequency that they pick up. You might want to add a DC current to your magnet to simulate this, and be able to use feedback. Or stick a permanent magnet on your core.
> 
> 
> Best,
> 
>  René
> 
> 
> --
> synth at schmitzbits.de
> http://schmitzbits.de
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org