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Expression Pedal

Started by Jamiroking, July 28, 2010, 02:16:32 PM

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Jamiroking

Alright, so after my 3 builds, there's only one spot left on my board and its reserved for an expression pedal. However, I have 2 pedals (maybe 3 if I can get it to work) that I want to use it for. I had decided to build one that can control them all since they all use 10kohm pedals. Unfortunately, I just found out that my Line 6 DL4 requires a TS expression connection and the Boss PS-5 and DD-20 use TRS.

Originally I thought they were all TS so I was going to add SPST for each jack so I could choose to which ones would be controlled.

1)Was this idea even feasible to begin with?

2) Is there a way to still do this with the TRS pedals?

3) Seeing that the Small bear wah enclosure is close to $50 I'm assuming this would just be better to mod an existing wah/volume/expression pedal

I'm thoroughly confused but this forum has yet to let me down!

pigyboy

For new wah enclosures keep in contact with Mike from http://www.pedalenclosures.com/
He is to have a new wah wah box up for sale soon.  You can buy a cheap wah with all the guts for about $50 too so you may consider that option. I am a bit 'tard when it comes to expression pedals though my wife wants me to make her one for her KT Tunstall looping master control nasa pedalboard. Let me know how you get on with this and what schematic you use. Good Luck.

pedalenclosures

Hi Guys,
  The wah enclosure will be a while.  I have another casting project in the works that I want to get into the world first...   Plus, I still have some research to do on the best way to go about the wah enclosure, lots to do, lots to do!

mike

Jamiroking

Dang. Well I decided to tackle the wiring problems first before even worrying about the enclosure

so I found this schem of the Roland EV-5 which controls the Boss pedals



From searching around I found that TIP= Signal / RING= 3.3V power / SHIELD(sleeve)=Ground

Now I know I definitely shouldn't just wire the 2 boss pedals together since wouldn't that make the RING input to the Pot 6.6V? Does anyone know which one is the actual return to the pedal that affects the expression, the TIP or the SLEEVE? Whichever one it is, do you think it would be possible to just let one of the pedals handle the other two pins and double up the pin that provides the output?

This is my first foray into schematics so it's tough wrapping my head around just what's going on

Thanks

Jamiroking

Well I made a few discoveries. Unfortunately, one of them is that I'm an idiot. The ctrl pedal jack on the DD-20 delay is actually just for a tap tempo which means I only need to control two pedals, one (Boss) requiring a TRS voltage controlling exp pedal and the other (line6) requiring a TS impedance controlled pedal which almost certainly means 2 pots since the voltage from the boss would probably zap the line6 if I hooked them up together.  But for those who still want to control two TRS pedals with one expression pedal heres my idea.


The ring powers the pedal but if we hook up both rings, all you're going to get is a bunch of smoke and some seriously messed up pedals so you would choose one jack to make the default (the one you would use if you decide to only plug in one pedal) on this default jack you'd wire the ring to the first pin on the pot. I just tested the PS5 and the voltage is still sent even if the pedal is not engaged so it will power the circuit even if you're only using Pedal 2. You also hook up pedal 1's sleeve from the ground.

As for the signal return through the tip, according to what I read online. I believe that the voltage will stay the same even though it's being split between two lines. LEt me know if I'm wrong on this. I had the idea of then using SPST switches to decide if you want the pedal controlled or not. it could be an A/B switch but I just know that I would eventually want to control both at the same time. If I'm right, this could be extended to however many pedals you wanted to control. But I definitely could be wrong

Jamiroking

no one?

Guess I lost my help when I got off PCBs