An off-the-wall idea for control

[Mark Hammer]

My wife has a "vintage" sewing machine from her mother, that uses a foot treadle rather than electric motor.  The belt was broken so I had to get her a new one.  The foot treadle operates a cam which turns a flywheel as it also turns the sewer and moves the needle up and down.  Because of the flywheel, the machine continues for a bit even after you stop pumping the treadle with your foot.  It's an interesting lag that is not unlike what happens with bagpipes or harmoniums, both of which "store" air pressure to distribute on demand.

But it occurred to me: what if the foot treadle operated a generator?  So you produce a control voltage as you pump a foot treadle.  But because it's a bicycle-type generator, it takes a bit of work and foot pumping to create an ever greater voltage, and the voltage takes a bit to drain off.  Why bother with all that effort?  Because producing a gradual rise and fall is probably a lot harder to do with direct control (i.e., via expression pedal) than you might think.  A treadle like the sewing machine allows one to translate one very slow foot press into multiple foot movements.

Nuts or what?  Sounds like the sort of thing Jack White would get the thirdman folks to make for him.

[PRR]

Just FYI: a foot-machine later updated with an add-on motor *may* generate your voltage with no hacking. Depends how much residual magnetism is held in the motor, if it will work as a generator. Since it is natively a 110V machine, getting 9V may be real easy.

[Fancy Lime]

I have been pondering the mechanical sewing machine mechanism for a tremolo in the past. Having a number of holes in a cylinder that is attached to the flywheel would give a number of pulses if an LED shone through the holes onto an LDR. Intersting rhythmical patterns would be possible. By have multiple different tracks of holes side by side, one could select different patterns by moving the LED-LDR pair laterally.

The generator control voltage idea sounds great for controlling slow moving modulation of a flanger or suchlike.

Andy

[Digital Larry]

There's a plastic swing at the local park that I used to swing my kids in (before they were 6 feet tall).  The back of this swing has a smooth concave surface and I noticed that if you talk while the swing goes past your face, the reflection generates a quite noticeable flanging effect.  So, if you could get this pedal to make the swing go, you'd have one heck of a pedalboard there!  Just make sure you don't tell the kids they have to go home before the gig is over, or there will be much crying.

DL

[Kevin Mitchell]

This talk about generating power from old motors brings back some memories.
Mostly about my first time hiking the tallest mountain in the northeast US. It was a long day and go figure, I didn't have a flashlight in my bag for the dark descent. My buddy had an emergency survival flashlight but it ran out of juice real quick. Every 20 steps we had to pause and take turns cranking the gear to get a bit of charge to safely continue.
That was a lesson we only had to learn once 

So! I think the most simple thing to try is connecting that pedal to an optocoupler and see how it swells. If it doesn't provide enough juice you can always amplify it (probably needs smoothing anyways). You can modify it further from there as a control source for filters.

One cool sound effect I have in mind with this is similar to blowing up a balloon, where every foot press increases the voltage. Would be cool for an incrementing volume.

[GibsonGM]

Washington?  Good times there, and more on Katahdin  

[Rob Strand]

I'm not 100% sure on the configuration but what occurred to me is adding a generator will mechanically load down the flywheel.  Using loadless sensing like optical or all sensors would avoid that.   Of course some circuitry would be required.  It's not that simple either if you want detect fine movements then the rotation sensor would need sufficiently fine resolution.  An encoder is perhaps going too far, and a pot, well that means we've gone back to a wah pedal!

[Mark Hammer]

Whatever the mechanism - and I'm not married to any particular one - the basic idea is that the foot-operated device increment to a summed control voltage with multiple foot presses, such that the resulting control voltage slowly rise and decay, although one can always adjust the bleedoff time of any held voltage.

The objective is to provide a different feel to things like filter sweeps or LFO modulation, than would be provided by other methods of real-time user control.  Coupled with expression-pedal inputs on pedals, I think it could be interesting.

[Kevin Mitchell]

Washington?  Good times there, and more on Katahdin

Yup!
I've routed out a plan for the AT, going from NC to ME (Katahdin). Would really like to do it while I can and have been thinking about it a lot lately. It's only like... 2190 miles. I at least would like to make it back home in western MA 

Sorry to derail!

[GibsonGM]

I always wanted to do that! Hope you are able to!  I live up along the AT in Maine.  I can see where the poor old lady got lost from my driveway.  Great area! Grew up in eastern MA, and almost moved over your way but opted to go north

[iainpunk]

i have wanted to build a Leslie speaker for guitar using this sewing machine method of speed control and motive force. would make it possible to control the speed on the fly, like a WAH pedal. i dont have the space to store such a unit at my current residence, and would probably not use it as i don't particularly like the sound of leslie on guitar, but it be a cool project.

cheers

[amptramp]

Have the flywheel turn a ten-turn precision pot and you should have the effect you need.  But this would have to have end stops so you don't overdrive the pot to mechanical destruction.  It will matter which direction the flywheel turns.  I could see you on stage with your guitar, seated at the sewing machine trying to get the setting juuuuust right without overshooting.

[Mark Hammer]

One very good reason why I prefer the generator/CV idea.  Even if one could bring a 10-turn pot to a gentle nondestructive stop, there is still the matter of returning it back to wherever it started out.  The generator/CV notion allows for production of a control voltage that can be maintained OR allowed to decay at some rate, once you stop pedalling.  No different than pedalling a bike to pick up speed, and gliding along for a bit once you stop pedalling, with that gliding period contingent on the flatness/incline of where you happen to be, and how hard you initially pedalled.

[Eddododo]

May be interesting to put a simple photointerrupter sensor with an actuator flag on the wheel, you could use it for a very 'organic' ramp up / ramp down leslie style control for modulation