Looper DIY

[glen2410]

SO I have a 3dpt switch lying around, That got me thinking.
I have a not-so-easy to switch pedal board where in the top row of pedals are hard to stomp on without hitting some other pedals knobs.
I'd like to build a remote switch that can select the pedals in succession. For example, On the first stomp pedal1 is activated,on second stomp pedal 1 and pedal2 is activated and on 3rd stomp pedal 1,2 and 3 are activated. The next stomp resets to only pedal 1 being active and the cycle continues. Only one 3dpt switch does the switching in the sequence.
Is this possible? Any guidance and schematic is appreciated.

[Elijah-Baley]

All this with ONE and ONLY footswitch?
I think there's no way for do this easily.

Probably you need something of programming or sort like that, processor, memory unit.
Interesting project, but over my skills.

[samhay]

It's 3PDT - tripple-pole, double-throw.
See: https://learn.sparkfun.com/tutorials/switch-basics/poles-and-throws-open-and-closed

As it is a XPDT, you can have 2 throws, i.e. 2 options. You want 3 options, which is do-able with an XP3T switch, but these don't exist AFAIK in stomp form.
This is the sort of problem that most people would solve with either multiple XPDT switches or a single momentary switch, some logic (prehaps done with a microcontroller) and relays or solid-state switches.

[glen2410]

Yes its a 3pdt switch,it was a typo
Anyways if i were to use momentary switches,how would I go about my idea?

[GibsonGM]

Yes its a 3pdt switch,it was a typo
Anyways if i were to use momentary switches,how would I go about my idea?

Electronic switches, my friend. They come on a chip. This can get quite complicated; I've seen very few DIY projects that incorporate them to any large degree.  Probably also need to look into shift registers and flip-flops, both of which are interesting building blocks to learn about anyway as part of a well-rounded electronics diet...

Having revealed how ominously complicated this kind of switching is, it CAN be done DIY, but you'll have to do your homework...search the internet, terms like "Digital switching project" and so on.  Someone here MAY have tried this, but few, I think.  It would take quite a bit of effort to make something practical, useful, and small enough for mobile use...

Let us know what you dig up!!   

[samhay]

If I were to do this as described by the OP, I would use a momentary switch driving 3 DPDT relays via an 8 pin PIC - probably PIC12Fxxx.
However, if I were to go to the bother of doing something like this, I would make it a little more versatile and have various pre-sets and perhaps 2 foot switches - on/off and bank up/down.

The other option is to make a passive box with 3 send/return loops - each with a 2/3PDT on/off - [edit: in series, not parallel].

[duck_arse]

well I'd do the mickey-mouse route. use a single push button switch with a one-shot (maybe a hex-inverter) feeding a 4017 or similar counter (maybe a transistor ring-of-three) with diodes steering the relay drivers (or gates on relay 1 and 2).

but don't quote me on that.

[Transmogrifox]

well I'd do the mickey-mouse route. use a single push button switch with a one-shot (maybe a hex-inverter) feeding a 4017 or similar counter (maybe a transistor ring-of-three) with diodes steering the relay drivers (or gates on relay 1 and 2).

A counter and relay drivers come to mind for me also.  How you decode the counter outputs to get the specific functions you want on the relays takes a little logic design, but it's all there for the taking. 

There is a possibility to include a bank of DIP switches so that you can modify what set of switches go in/out on each sequence.  Obviously the most simple design will be the hard-wired 1-trick pony.

but don't quote me on that.

I couldn't resist.  It seemed like some good ideas are in there

[chicago_mike]

If you want to go the pic route, you can use a PIC12/16 and get some shift registers.    Nepotism alert! My brother works at Microchip so I get freebies often.   

[glen2410]

I dont have a lot of experience with mc and counters and stuff. Anychance I can get a rough schematic so that i know what exactly I should research?

[duck_arse]

if you can wait a day, I can cobble some circuit idea with counters and stuff into a diagram, but if 'mc' is for microcontrollers, I'm pass on that.

[glen2410]

if you can wait a day, I can cobble some circuit idea with counters and stuff into a diagram, but if 'mc' is for microcontrollers, I'm pass on that.

Definately can wait a day. Lemme know what you come up with. Appreciate it

[PRR]

> I'd do the mickey-mouse route.

More Mickey Mouse:

The job wants a THREE-Throw switch. These are readily available as 4P3T for a dollar.

But these are rotary switches.

First thought is to mount the switch shaft horizontal and jam a wah-like treadle on it. Toe down, config 1, flat, config 2, heel down config 3.

Probably want to rig the treadle on its own sturdy axle and couple the switch with a short rubber hose.

But that requires a large ankle-angle (probably +/-30 degrees).

And lacks the roll-over action (from 3 to 1) which was requested.

So then we look at a motorcycle shifter. Toe-press works a ratchet which turns an internal drum/cam one notch. While the motocycle mechanism does not allow a 4-1 roll-over and does allow (heel-press) a 4-3-2-1 backward action, we could make it ratchet 1-2-3-1-2-3.... The rotary switch has an internal stop between 3 and 1. But they use the same pressing for 2T 3T 4T and 6T switches. So you can probably bust-off some tab so the switch rotates continuously.

Yes, a motocycle Mickey-Mouse will be larger than a bell-button and a mini brain to count the 1 2 3. But it does not involve abstract concepts like Programming. Hold a switch and a treadle, carve a ratchet-wheel and finger out of a tin can or large knob, start mounting on a slab of plywood (or an actual bread-board).

The other thought: there are finger-press several-way switches for 3-Way lamps. But these are usually 4-way (including Off); and usually 1-Pole (no complicated re-connection). And they are not stomp-worthy. (And the turn-knob type is far more common than the press-type.)

[duck_arse]

here is my relay counting circuit. ....and here it is for the colour averse.



it counts once with each press "step 1", the apparent sequence being 0, K1, K1+K2, K1+K2+K3, 0, unless/until reset (to 0) by pressing "reset 0".

both pushbutton switches are debounced by Schmitt inverter circuits (which the interwebs garantee will work). the counter Q4 output and the reset pulse are fed via a diode OR gate (D6, D7, R5) to the counter reset pin. a high pulse on either anode sets Q0 high, turning ON the K1 coil. (this will save some current, as there will only be max 2 relays on at any time.) because of this, the normally open K1 contacts need to be wired as the normally closed K1 contacts, and vice versie (K1 ONLY).

K2 is fed by the diode OR gate (D4, D5, R6) connected to Q2 and Q3, and tuns on when either of those outputs is high. K3 is the dullest of the lot, it just switches on when Q3 goes high, and the next counter increment will reset to 0 relays, or the bypassed state.

the 3 leds are driven by the C, D, and E inverters to indicate the count number, 1-3, and only one is on at a time. choose your own colours and current limit value. IC1 can be replaced with a 4584 (or a 74HC14 with a 5V supply), IC1F is spare and parked, it could be used for a power-on reset.

it is for the builder to work out the relay contact wiring, it's beyond me at this point. no supply decouple is shown. the circuit will work (and if it doesn't, I don't know why not) with 5V, 9V or 12V relays, but you must match the coil voltage to the supply voltage, and the driver mosfets to the relay currents. I have not buit or tested any of this circuit.

[glen2410]

^^ This is brilliant! Now I have something to work with. Really appreciate the help.

[duck_arse]

let us know which parts catch fire, OK?