Looking for ideas on how to convert sound to spring motion

colorado_hick

Well-known member
Hey folks,
I am working on a synth chassis that has a goat skull mounted on an upholstery spring (like a bobblehead). I am looking for it to have subtle nods that are correlated to what is happening in the music.
My first idea was to do some sort of beat detection and drive a stepper motor with connecting arms between the skull and the chassis but it is really rigid feeling. If I just give it a thunk right now the skull will bob for a minute just with the energy in the spring and I like that fluid motion.

I am wondering if there is something else less ridged that I could use to actuate spring motion? I have a basic understanding on how spring reverbs work, is it realistic to drive some sort of magnetic coil with my sounds and have it create motion? I rather stay within 5 volts, i do not know if I could create enough magnetic flux.
 
Perhaps it is possible to make the connection to the stepper with a second spring? And let it do microsteps?
 
Could you do something with a big base speaker?

I thought about that, but the way that the chassis is laid out I am not sure how it would work. I was thinking of maybe pulling the voice coil from a big speaker and then mounting some sort of magnet on the head for more of a magnetic drive, but I dont think I can get enough flux
PHP:
in the voice coil because the skull is 5 inches away. that would be a log pull for the magnet I would think.
 
Perhaps it is possible to make the connection to the stepper with a second spring? And let it do microsteps?

Or maybe a servo or two - again with a proper weight spring inline. It would not tend to deaden it. One could go left or right - A pair could pull one left the other right.
 
I once had a setup that was perhaps something similar. Instead of a step motor I used an ordinary DC motor. The controller could switch this on for just rather small time pulses.
The lever on the motor axis was so long, that the motor could move only for some angle, not full revolutions. In my setup gravitation braught back the movement of the motor.
 
A small solenoid that you just turn on for a small amount of time maybe limit it with some rubber to avoid the clicking sound.
Or if you have a old hard drive there is the read arm that is driven by a kind of voice coil.
 
I liked the idea of using a loud speaker and simply feeding it your audio. But, you don't really need the full loudspeaker. You can buy just the core transducer part without the cone. Much smaller and easier to work with. They're called surface transducers...

https://www.adafruit.com/product/1784

You could mount your spring directly to the transducer. Power it up and whatever audio is near the resonant frequency of your spring+skull system will cause it to shake.

Chip
 
What about a solenoid, you would need to activate it with a relay. I'm thinking something like a pinball flipper (or several), maybe it can yank on the spring with a piece of fishing line.
 
Here is a little video for context. This is after a light thunk, it is a great spring and will go for a while on its own.
[video]https://photos.app.goo.gl/gwMee9HnDmcTCkj66[/video]

After all of the suggestions I am leaning towards doing some sort of solenoid or stepper motor attached to something with some weight that is inside the skull cavity. I could move the weight around which would change how it balanced and translate to some movement. More of a hipster nod then a head banger but thats cool. It might be hard to connect it to the music but I could some how make it like a module that interacts with an oscillator. I fear the haptic and transducers will be to high frequency will not do the large-scale movement and I do not want any extra arms or lines between the skull and the chassis.
Thanks folks!
 
Back
Top