how can i use ONE expression pedal to control SEVERAL different effects....

[pinkjimiphoton]

one at a time? i'd like to shed some weight off my live board and ditch the univibe and crybaby etc for lighter gear.. i've been building a lot of stuff designed to accept an exp pedal for real time control, and it would be really cool if there was a way to make a box or something that accepts a normal control pedal, say an ev5 or quiklok universal exp pedal <usually 10k-ish pot> and then has a bunch of outs to switch it to so you could say, use one pedal as a wah, or as a univibe speed controller, or a flanger, or volume, or delay time or whatever. just one at a time.

i realize i could likely do this with simple analog switching, but i figure you guys may have a better plan.

maybe some kinda cmos switching? this is way above my humble paygrade, so all ideas and suggestions encouraged and welcomed.

heck, maybe even something programmable if its not too hard... arduino or something?

i mean... i'm just now getting into silicon transistors after starting on tubes and moving to germanium... lol

thanks guys. i figure if we can sort this out, it may be a worthy project!!

[ElectricDruid]

The way *I'd* do it would be to have everything on the board with CV inputs, and then you'd just be able to route the expression pedal CV output to whichever pedal you wanted.

But I'm a synth nut too, so this may not appeal. Also the CV-controlled crybaby is a thing, but not a simple thing.

That said, there's a lot to be said for pedals with CV inputs. Pick a CV standard and build stuff that fits it. I use 0-5V, since that's convenient for a lot of cheap processors and also for eurorack synth gear so you can patch your modular into your pedals, or vice versa, for all types of craziness.

HTH,
Tom

[pinkjimiphoton]

why, thank ye sir tom of wiltshire!

yeah, could do that, but i think we've well-established my lazyness factor. i'm willing to go for hours on something new, but re-work something old? my chromosomes rebel violently lol, the crippling fear that the 20 lbs of crap stuffed in a 1590b will never work again if i try and fit it all back in.

what i was thinking was more like, ya gotta simple switching thing done somehow.
maybe a box with 4 or 5 stompswitches on it, a corresponding # of outputs and one input for the expression pedal. that way, the simple normaled switching jacks i used on these things to break the connections to a pot <like i did on my flangelicious for the speed knob> will work fine.
i'm thinking it would need to be buffered at least on the input side, maybe the output sides as well.  to be able to switch it tho from the one input to the outputs and keep them isolated seems like it would need momentary non latching stompswitches, and do the switching with maybe fets or a chip or something?

this is just kinda way above my paygrade as a fuzzmonger, so advice on what/where to look to do this would be gratefully appreciated!

[garcho]

*EDITED*

sorry, just reread the part about switching.

CMOS switching can do whatever you want it to. You could have one momentary footswitch cycle through the different outputs sequentially.

[garcho]

^ dunno but maybe that could give you some ideas. i threw that thing together super quickly for a gig, huge room for improvements but it worked. might be a thread here but it was a long time ago now, i would do a few things differently (and breadboard first) but maybe it'll give you a place to start. 4 inputs, 1 output, selected sequentially with a foot switch (as well as having a manual override so you can select more than one channel for outputting).

[marmora]

Not DIY, but I remembered seeing this:

https://missionengineering.com/shop-2/products/expression/multi-use-exp/expressionator/

[moosapotamus]

Replacing one exp pedal with another box is still going to take up space on your board. If you want to scale down but add the functionality you're talking about, how about going lo-tech and mount a multi-gang pot in a single crybaby shell? You could go with a 4-gang pot, each one wired to it's own output jack, with toggles to enable/disable each output. Wouldn't be a stretch to add LEDs to indicate which CV outs were active. Or, you could use a single rotary switch to select the output, if you didn't want to have more than one active at the same time (but, activating multiple CV outs at the same time sounds like a lot more fun!).

~ Charlie

[anotherjim]

Thing is...
When the exp isn't selected to an effect, but that effect still needs to be active with the last exp setting -  how will it remember?
If CV, it will need a sample & hold, but then it also needs a control "gate" to tell it when to obey the pedal value or the last held CV value.
Really, you're looking at some kind of serial bus interface. The automotive industry CANBus in 2-wire form would be simplest. Basically, everything on the bus is listening to the transmission from the controller and only obey commands with their name in it.  In the fx you have a receiver with a digital pot or a pwm control of a vactrol.

[pinkjimiphoton]

well, in general its fairly rare for me to need two things simultaneously to be controlled with the exp pedal.  when i say use it as a wah, i won't be using it as a univibe, if ya get my drift.
control voltage would be the way to go obviously for stuff thats new, but retrofitting older things?
not so much.
seems to me the big issue would be using analog switching. would need a "make before break" matrix where activating ONE switch would deactivate any others, like old fashioned radio buttons. but that's not a viable choice either, as nobody makes those in a form that would be useful anymore.
thats what leads me back to electronic switching.

i do NOT want just one switch to do everything. to me, that's not gonna help... nor would a multi pot deal, as it would affect each unit all the time, and the odds are the taper wouldn't work for all so well, something i hadn't considered til now.
being a cripple, bending over to do toggle switches is not feasible. its gotta be footswitches. one for each effect, but when ya press one, it needs to automatically disconnect whatever came before it, that was engaged.

the obvious thing that comes to mind to me is to use fet based switching like a boss pedal, then soft touch momentary switches would work and you could "turn on" whichever output ya wanted. even i can grok that part pretty much... but then the problem becomes, how do you isolate each unit? how do you use 4 circuits to control the one circuit itself to switch the output?

thats where i'm thinking may have to go with arduino or something.

yeah, its adding another pedal to the board, but odds are that one pedal will take up less space and weigh much less than a crybaby and a univibe with controller and a flanger and a wah...  just the three treadles adds 10lbs of weight to the board. 1590b's are a lot lighter, and you can fit a lot into them.

so i was thinking it would have to start with some jfets to switch the one input from the expression pedal to one of 4 outputs. but this is where it gets really hazy to me, as its unlikely i'd ever develop the knowledge or skills to sort this out on my own.

of course, the other issue is that doing the way i have things set up now, with an analog interruption of a pot by inserting a switching jack between the circuit and the pot, is that i would also have to have each switch short the tip and ring connections back to lugs 2 and 3 of the pot... that are interrupted by the physical intrusion of the 1/4" jack.

there has to be a slick but easy way to do this. one concern obviously is noise pollution from clocks bleeding between the units that have them.

i guess i gotta read a lot of shit and try and wrap my head around it somehow.  it seems i could kinda do it with 4 4pdt switches, analog. but i just have a feeling its not gonna work out so well. maybe i'm wrong.

shit, if i COULD go control voltage, thats easy. i used to just put a 9volt battery across a plug, plug it into a volume pedal input and take the output to the control voltage jack. easy breezy.
but in this case, it's not always control voltage being manipulated, its audio. which sends me right back to the beginning again.

appreciate the ideas guys. garcho  i'm gonna take a hard look at your schematic, its actually opposite i think of what i'm trying to do, as i need one input to 4 outputs not the reverse. i agree, cmos switching seems the way to do this...  but what would be a good chip? or would i need a different chip for each "channel"?

thank you all!!

[pinkjimiphoton]

Not DIY, but I remembered seeing this:

https://missionengineering.com/shop-2/products/expression/multi-use-exp/expressionator/

thanks marmora,
thats about what i need, i think. but me? spend 200 bux? not gonna happen. i can buy a lot of parts for 200!! lol

[MrStab]

does anyone else ever think of ideal, magical, space-age solutions to problems then whittle them down by what is and isn't possible, and what you are and aren't capable of? i haven't yet gotten round to to the whittling-down part on this idea:

small high frequency pulse generators on each pedal input and several listening circuits on the expression pedal. 555 timers, trimpots, scope, band-pass filters, flip-flops, unicorns.

[pinkjimiphoton]

.......................... what?
lol
dude thats so far above my australopithecine understandings its confounding

that said.. pretty sure unicorns don't exist.

that said, that expressionator will do about 90% of what i want it to do. its 200 freekin bux, but...

i did get the cat to send me a pic of it, i inquired if it was possible to order one without the switches installed, but its all mass produced i guess.

thinking i could rehouse it, and add three stompswitches to it to be able to select which outputs are active. with that thing, you can actually control three units simultaneously, and it remembers taper and everything. its really slick!




i'd use it primarily for wah and to control the speed of my flangelicious <props to tom w. for that piece of kit>, and MAYBE my ludwig phase II, which i'd LOVE to use live. if i ditch the freekin crybaby off my board, i can easily fit it on and ditch the freekin' univibe, too. may be a win-win.

but 200 is money i don't have handy right now. so...

i've been thinking about a few different approaches, and i'm still convinced its gonna take some digital magic. i see a lot of other people have tried here, some have succeeded

i probably won't. i'm a fuzz guy not an electron physicist

[garcho]

You want 4 footswitches, each one turns that specific effect on and simultaneously turns the others off, right? So, footswitch A tells, say, a 4066 to open channel A, by closing an ON circuit, kind of like a relay but electronically. that same voltage can be put through an inverter, like a 40106, so the other channels receive OFF voltage. You might eat up some pcb real estate going this route but once you get your head wrapped around ON/OFF you can do whatever you want. You need to debounce switches but that's easy, worry about that later. And you'll maybe finagle the LEDs and deal with popping or some random issues like that, but you're familiar with all that already from non-CMOS digital circuitry. The thing to do would be to spend some time with CMOS chips and a breadboard and get your head wrapped around digital ON/OFF signals, and during that process you'll find the right combination to do whatever you want and come up with a million other ideas. Have you ever noodled with noisemaker CMOS "synths"? They're a great way to familiarize yourself with what basic digital ICs can do and make weird sounds in the process. Like this, a great if terse intro to CMOS:

https://milkcrate.com.au/_other/sea-moss/

if you like that stuff, the wonderful musician and audio artist Nicolas Collins has a great book called "Handmade Electronic Music"

[pinkjimiphoton]

wow, thanks for buying me two vowels and a consonant.

i am gonna rre-read this a few times til it sinks in. it looks like it  could do what i need, or close to it.

the allure of the expressionator tho is when ya switch from one effect to the next, it leaves the first pedal "digitally" at the same setting it was left at, and does both cv output or analog audio exp.

pretty cool tho. i will sort it out eventually, thanks for the help!! i will google up the datasheets for those chips in particular and see if i can wrap my mind around them. also will check the cmos page again, thanks for the tips garcho!

[anotherjim]

There is a non-microprocessor digital approach, and you could use miniature signal relays instead of CMOS switches. Up/ down momentary footswitches step a counter chip. The outputs of the chip are decoded to show the number of the selection on 7 segment display(s).
The fx have switched TRS jacks for the exp that leave the normal onboard control active when no exp plugged in. The controlling exp "box" has a set of control pots that take over from the one in the fx when plugged into it via a TRS jack. There is one for each separate fx to be controlled in addition to the exp pedal pot. When the up/down counter selects an FX, the relays switch the pedal pot into action for that selected effect.

[Ripthorn]

I actually have a design in the works to do exactly this. I had the thought a couple months ago when putting together my new board.  Basically, at the heart of it, is a microcontroller and an analog crosspoint chip, which will allow me to create presets that I can then select for whatever I need to do. The crosspoints are NOT cheap, but are super flexible. I've got a schematic all together, but I haven't prototyped it yet (waiting on some parts to come), but I do plan to post a full build doc with schematic and MCU code when I am done. I will also be using it (a second one) as a programmable patch bay. The crosspoints are bidirectional, so you can make any jack an input or output.

[pinkjimiphoton]

you sir,
are my hero.

please keep me in mind when ya release the project! and i'd be more than willing to help finance some boards or chips if necessary! this is sooooo far above my fuzzmonger paygrade, i'm very grateful you offered to share.

was looking at the expressionator, but its kinda hard to justify the 200 bux on something that's "close" but no cigar!

thanks man!

peace
pjp

[Mark Hammer]

Late to the party, Jimi.

Missing from all of this discussion is mention of what the expression-pedal standards are that are used in the pedals you wish to control.  For instance, some, like the Line 6 pedals and some others, just use a 0-10k variable resistance to ground.  Some expect you to supply an external control-voltage.  Some feed a standard voltage out to the expression pedal and the pot in the pedal simply divides it down.  Does the divided-down product come in on the tip or the ring connection?  Is the range of the control-voltage 0-3.3V, 0-5V, 0-9V, something else?  I have one of those Source Audio Hot Hand units, and it provides 3 possible "control" outputs: two 0-3.3V outputs, and a 0-10K resistance, so you can plug it into different things.

From where I stand, you first have to define what sorts of "control" you plan to use, and the type and diversity of expression-control will dictate the potential solution.

[pinkjimiphoton]

well, in my case, i need it to replace a hardwired pot in three effects, maybe 4.

one for the speed of the causality 4 phaser, i use a normalled trs switching jack inserted to interupt before the onboard pot.

one for the flangelicious phaser, doing the same thing.

and one for the ludwig. the same pedal i use with the ludwig also works well with the other two, and i designed a remote wah to work with an expression pedal, too... most of the actual "wah" range of a wah is only around 10k of the pot so it works great if ya use a bigger inductor and a smaller cap.

so, like, 3-4 things i'd like to be able to switch it between. i imagine its gonna take more than just analog stuff to do it.

the expressionator actually uses an arduino in it i guess to keep the levels constant if ya switch the pedal's function. its a pretty hip circuit.

so i don't need to really mess with cv, i mean i AM by doing it the way i am, i guess, but its fairly rudimentary, which works good for my simple hippy brain

i'd probably bite at the expressionator, but to me, it should have had the channel selector switches be stompswitches so you can program it standing up, with my back, i want EVERYTHING foot controllable i can. bending over sucks!!!

anyways, the expressionator lets you do a whole lot, but not being able to access the programming function without pushing switches with fingers that imho would be better served as stompswitches is kinda a deal killer. i don't wanna spend 2 beans on something i know i may break molesting.

cuz you KNOW 30 seconds after arrival i'd be hacking on it

so anyways mark, thats my vision. i'd love to build a box where i could switch one standard 10k expression pedal like the quiklok universal one i'm using now for everything from one pedal to another. there's problems with doing it the way i have already set the things up... as soon as ya switch the pedal, there's no pot on the normalled jacks anymore, the circuit's broken.
so yeah, could use stomp switches and have it go from exp to a preset trimmer, too, i suppose, but it would be a fairly complicated switching matrix i think and i am a fairly simple dude!

[garcho]

CV is used with certain ICs, OTAs, etc., but it's not really gonna give you a rheostat, let a lone a potentiometer. Microcontrollers can control digital pots but those are usually resistor ladders. 8 bits gives you 256 "rungs" on the ladder. I doubt you'd hear that on a phaser/flanger, but you might here that on a wah. Like on my 17 year old car stereo; a one notch turn of the volume control and the music goes from not loud enough to louder than i want. Plenty of effects with digi pots that work just fine, but something to consider, anyway.
As you mentioned, the main issue is if the pots are bypassed by a physical cable jack, then short of removing the hunk of metal closing the switch, how can you "tell" that pedal to ignore it and go back to using the pot instead of the expression pedal? I don't think you can. I know your pedals are crammed full of a rat's nest of yummy little electro snacks already, but you would have to add electronic switching at each pedal, then maybe use a stereo cable or something so you can send the ON/OFF messages to the switch from the expression pedal. Otherwise, the pots on the pedal will be permanently bypassed. That's your conundrum, yeah?