If I were to, hypothetically speaking*, attempt to build a guitar pedal inside an 8mm film canister, with inside height of 9/16-in. (14.29 mm), would there be any reasonable options for a footswitch?
(https://i.imgur.com/vv1FZGhl.jpg)
*I only rarely finish anything I start, as I've proven many times.
A push button switch + JFET switching would help. The switch in the old 1990's "Lady Bug" enclosure pedals was a very small push button. SMD might help also. However using one of those complicates the mechanics. You would have to add something to form the foot part of footswitch.
The pots and 6.5mm jack will be pushing it also.
From a reliability perspective, I'm not fond if these types,
(https://www.eedesignit.com/wp-content/uploads/2016/12/ultramecimageee.jpg)
You would need a spring coupling to prevent damage to the switch.
JPR electronics in the UK sell a 'vandal resistant' switch that would be on/off only (no bypass without you adding something clever) but if you added three hex nuts to its shaft to make the bulk of the switch project out of the case, the lower half would fit in the film cannister. The curved buton version of the switch might be OK for feet?
https://www.jprelec.co.uk/categories/components/switches-and-sensors/vandal-resistant-switches/vandal-resistant-16mm-switch--ip65-sealed/product/vandal-resistant-16mm-switch--ip65-sealed/800-537~800-537 (https://www.jprelec.co.uk/categories/components/switches-and-sensors/vandal-resistant-switches/vandal-resistant-16mm-switch--ip65-sealed/product/vandal-resistant-16mm-switch--ip65-sealed/800-537~800-537)
https://www.jprelec.co.uk/pdffiles/800-537-538.pdf (https://www.jprelec.co.uk/pdffiles/800-537-538.pdf)
1) A hollow container like that will be noisy. Bandmates will be able to hear the switch being pressed.
2) I suppose if the base of the switch is butted up against the bottom of the canister, you may have few issues, but it is likely to be flimsy and easily give.
3) Normally, one wants footswitches as close to the outer edge of the enclosure as possible, to facilitate ease of foot access.
My advice would be to find another enclosure.
The normal 3PDT footswitch for true bypass does not seem to be all that possible here. You need an SPST switch and the kind of circuitry the Boss pedals use for switching. There is a much greater variety of SPST normally off switches than 3PDT alternate action ones so you will be able to select different styles including the low-profile ones you need.
I did propose designs for bypass switching using SPST switching and a different design of switching circuitry in this thread:
https://www.diystompboxes.com/smfforum/index.php?topic=120006.msg1122270#msg1122270
Wouldn't that flex enough that a tactile switch connected to electronic switching and mounted inside close to the face, or touching the face, would be triggered by pressing that face of the tin. The whole face is a pancake actuator. (Geofex)
dave
How important is it that the tin be unmodified? You could easily slip a cylindrical spacer around the edge (but inside the tin) that would raise the top just a smidge and get normal parts into it that way. And the existing lips of the tin would cover the cylindrical spacer. Could be made out of a strip of sheet metal curled into a ring shape. Maybe pop-riveted to the bottom half's edge just to keep it in place.
I was thinking along the same lines as Dave before I scrolled down that far. Is the tin really strong enough to withstand "excited guitarist"? You might need to pack it with enough strategic hard stuff (to limit movement) that there's much less room for all the pedal-related stuff you want to house in it.
But never mind that. I wanna see this happen. ;D
Thanks for the input, everyone!
Something about this film can makes me want to see it decorated with an arc of 8-10 potentiometers. :icon_twisted:
Maybe someday I'll figure out exactly what to do with it.
I'd love to keep it the same thickness rather than expanding it to accommodate standard stomp switches, but I'm not completely against adding a riser underneath to create extra "hidden" depth.
Also, I agree with Mark that the shape and thickness of this thing would likely preclude stealthy activation of a conventional stomp switch. I think a soft switch with supporting switching electronics would be the best way to go. I actually have a soft touch DPST off-(on), on-(off) footswitch that would fit, but the threaded bushing would stick up by a comically large amount.
Plenty of thinking to do still.
I wonder if there could be a way to create a reliable piezo element tap sensor to activate a pedal circuit....
Have you thought about 1/4" jacks yet? I can't see the edge very well, but may be quite tricky to mount jacks there, maybe too thin, and there's not enough depth for vertical.
FWIW, the "low profile" 3PDTs that Small Bear and others sell will not work, they need >16mm clearance.
Was initially thinking Lumberg jacks could work with some sort of gaskets to fill in the irregular shape. But, that is as far as got before I set aside that question and shifted my thoughts to the footswitch. If I had to modify the can for a footswitch, I figured the same modification could address fitting the jacks.
I'm liking the idea of making a piezo knock sensor.
Perhaps something based on this:
(https://elonics.org/sites/default/files/inline-images/piezo-knock-sensor-using-555-timer-schematic.png)
https://elonics.org/piezo-electric-knock-switch-using-555-ic
I'll probably conduct some experiments as soon as I find something to harvest a piezo element from.
Quote from: EBK on September 13, 2019, 09:39:21 AM
I'm liking the idea of making a piezo knock sensor.
Perhaps something based on this:
(https://elonics.org/sites/default/files/inline-images/piezo-knock-sensor-using-555-timer-schematic.png)
https://elonics.org/piezo-electric-knock-switch-using-555-ic
I'll probably conduct some experiments as soon as I find something to harvest a piezo element from.
Careful, if it's sensitive enough to switch with the tap of a foot, it'll be sensitive enough to switch at the sound of a kick or snare behind you :icon_lol: