DIY Expression Pedal

S

stratcat

Inspired
:cool: :cool: :cool:

Just something I cobbled together... I'll post more information if anyone's interested too.

I built this to use in addition to my Boss FV500 which I use as a volume pedal, but don't like for wah usage... and I wanted a seperate wah pedal anyway.

I've also built it to have some improvements over store brought expression pedals:
  • It has a switch - i.e. "toe down" position switch like a normal wah pedal to switch the effect on. :)
  • Plus an LED 'on' indicator :)
  • This means it needs two outputs :| (switch output + expression pedal output), but I'll use a single 5 conductor cable with 2 plugs on each end to carry both signals back to the AxeFx :)
  • Pot is a linear taper 10k pot which gives a nice even sweep for the Axe :D
  • I've put a polarity switch on the back to switch the expression cable polarity so it can work with different devices (e.g. the AxeFx requires this a different way around to the MidiMate) :D :D

Piccie #1. Parts received in from Small Bear Electronics. A few other locally brought bits not shown. Also not shown was the rubber insert for the top bit - I had some treadplate which I wanted to use (see below).
parts.jpg


Piccie #2 & 2a. Guts of the pedal. Perhaps a bit messy, but not much to it.
guts.jpg


Piccie #3. (Almost) Finished product. Pin needs to be pushed in and I have a little plate for the back that's yet to go on, otherwise ready to go.
new.jpg


The best bit - none of this is rocket science!

It's basic electronics - the pedal needs 2 switches, 2 output jacks, 1 pot, 1 LED, 1 resistor, battery clip and battery, some soldering. Aside from that it needs a bit of body filler (if you don't use the side holes), sanding and some spray painting. The treadplate on top I had left over from another job so cut some to size to fit the pedal (I decided I could do better than the rubber insert they provided).

If you can make/fix a guitar cable you can make this (this is the about the limit of my electronics experience, although I did have a Radio Shack 150-in-1 kit when I was a kid :) ).

It's been a satisfying project, I'm really happy with the result, and it's been purpose built to work with the AxeFx and other midi devices whilst taking care of some of the issues I've had with store bought pedals. I'll probably make another one (when the exchange rate with the $US gets a bit better).

:cool:

Chris
 
The footswitch is just a standard latching switch - this has its own output which goes to one of the 1/4" pedal inputs on the AxeFx. The other output is for the expression pedal and goes to the other of the 1/4" pedal inputs on the Axe.

On the Axe I then have these assigned to : Pedal 1 - Wah Bypass, Pedal 2 - External 2->Wah frequency.

That's it - there are no other clever electronics involved (although in my case, using an LED and a resistor counts for clever electronics...). The AxeFx does all the hard work from there.

To operate as a midi controller it would need to go into the pedal input(s) on a controller like the Midimate which you could then set up to send a CC message via midi everytime you hit the switch or operated the pedal.

Any midi controller that has external pedal capability should be able to do this. The Midimate only has one pedal input though so isn't very good for this purpose (and in my case is tied up with the FV500 as a volume pedal) - LiquidFoot, GCP etc would handle both (and more) signals so a better choice.

btw - The other switch on the back switches the polarity on the and ring signals on the expression output.

:cool:

Chris
 
Nicely executed project you've got there. Did something similar with an old Cry Baby wah a few years ago.
Only thing I haven't done is adding a status led. The Cry Baby's spst-switch wasn't up for it.
Haven't gotten around to exchanging that for a dpdt-switch. Might have to give it a go, now that I've seen yours.
 
Bumping an old thread...

Stratcat - Is there any way you could draw up a quick wiring diagram for the dpdt switch?
 
I am just not a DIY guy but this is so freakin' cool I might have to suck it up, good job man!

What was the total cost for parts (US)?

Thanks!
 
I'm not going to fully admit what mine cost... :oops:

Cost of pedal shell, electronics - approx US$57

Cost of overseas shipping for a wah pedal shell, plus cost of auto body filler, paints, water decal paper - approx US$50 total, maybe more

Knowing that I built it myself - priceless :lol:

Whether or not all the extra stuffing around was worth it just to get the outputs on the "top" of the pedal - the jury's still out on this.

Braincells killed off during application of auto body filler - 2,759,136

Does opening the kitchen window constitute a 'well-ventilated area' - no

Swear words used during application of water decals - 39

Car trips to Bunnings (Home Depot) for sandpaper and paint and auto body filler - 2

Cost of BBQ'd sausages in bread purchased at Bunnings - $7.50


:cool:

Chris


ps - switch diagram still coming. Bit slower than usual on these things this week.
 
bump.........


is the switch just a standard dpdt switch to hook up with the mfc 101 as ive converted a broken crybaby and would like to add a switch back in for this
 
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