Adding an expression pedal input to Soda Meiser!

[Kli Klis]

Hello everybody! (:

A friend of mine recently asked me to build him a Soda Meiser, which is practically ready - save one thing:

He asked me if i could add an expression pedal input to use for the Intensity knob. Having read the (not so many) articles about making such mods after googling, it seems that nothing actually suits me, since the pot is not connected to ground on any lug. Geofex doesn't give any insight on this situation; he just says

"There is a third possible hookup for a speed control in the pedal that uses all three pot terminals but the third terminal does not go to ground. That would be more difficult, and we'd have to use the "advanced" method of controlling the effect - an LED/LDR variable."

while experimentalists anonymous give a more specialized article on a modfx pedal, which i'm not sure will work the same way.

So. How hard is it? What do I have to do? Is there really no easy option on modding the pedal that way? Or is it just a misunderstanding on my part and I just need to use the tip for 2nd lug, and the rest either way? Also, since the pot is 100 log, should I mod an expression pedal for the guy, or it could work with the standard 10k exp pedals?

I'll link the vero and the schematic for reference. Thanks in advance!

Vero: http://i76.photobucket.com/albums/j6/IvIark_2006/Layouts/Vero/Effector13SodaMeiser.png
Schematic: http://i54.tinypic.com/fk2nie.gif

[wavley]

You might check Devi's now defunct forum, she has all sorts of mods for her stuff over there and the forum is archived.

[Kli Klis]

Thanks for the advice! Unfortunately, after double and triple checking all the topic pages, despite finding some great stuff, it didn't answer my question. So... Still waiting for an answer (:

[Barcode80]

Buy a PLASTIC switching jack. The lugs that the cable contacts need to be wired to the board in place of the intensity pot. The 3 lugs on the other side of the jack should be wired to the pot lugs. make sure they are wired the same (if lug 1 on the pot is going to sleeve, for example, the contact side of the sleeve connection needs to go to the board connection for lug 1). Voila.

[Kli Klis]

Firstly, thank you for your quick and thorough answer. Secondly - I understand that you mean these jacks: One, Two (though the second has 5 lugs, and i'm not sure if it is the right one). Now I have to find one of these in europe, just please validate that I've got it right...

Also, I have a question: How exactly are the 6 lugs of the plastic enclosure connected? Are they short-circuited when there is not a jack inserted, and stop connecting when there is? If they are, I have one of these, so I thought
1. Short-circuiting the side lugs of the pot to the lugs of the jack and straight to the board
2. Having the 2nd lug of the pot to the switch lug of the jack
3. Having the tip of the jack connected to the board

so in a nutshell, whenever a jack is inserted into the connector, the second lug of the pot is disconnected from the circuit, effectively isolating the pot from the circuit. Is my thinking correct? Or I still have to find the plastic jack casing?
Thanks again for the input!

[Barcode80]

The one you labeled "one" is the one you need. You need a plastic one to isolate the jack from grounding to the enclosure. The metal ones have the sleeve connected to the chassis when mounted. So if your control doesn't connect to ground on any lug, you don't want a metal one. Unless you use a plastic enclosure. The gist of it is no metal on metal.  

EDIT: and yes, your understanding of how the jack works is correct. the contacts on either side of the jack are connected when no plug is inserted. Once you insert the plug, the connection is broken, and the board connections run out to your expression pedal pot.

[Kli Klis]

Thank you oh-so-much  

I totally forgot about the jack contacting the ground -.-
OK, I found the jack in Banzai (dear future people: Here, here, and there) and all is well!

One last question, mostly educational: How is a typical expression pedal going to behave? Since from what I've read they mostly go around 10K lin, while the pot is 100K log. It is of course better to mod an exp. specifically for this (and i'm probably going to), but do you think an industrial default pedal will be satisfactory in any way?

[DavenPaget]

BTW , tayda stocks them at 0.46$ 

[Kli Klis]

Hum... and is it reliable? I... whaaaa? $1.80 shipping? o.O

erm... thanks?

[Barcode80]

Thank you oh-so-much  

I totally forgot about the jack contacting the ground -.-
OK, I found the jack in Banzai (dear future people: Here, here, and there) and all is well!

One last question, mostly educational: How is a typical expression pedal going to behave? Since from what I've read they mostly go around 10K lin, while the pot is 100K log. It is of course better to mod an exp. specifically for this (and i'm probably going to), but do you think an industrial default pedal will be satisfactory in any way?

If you are using a 10K expression pedal, it will limit your available control to the first 1/10 of the original pot's rotation. However, most wahs use a 100k pot, so if you can find one to salvage, you can do it that way.

[Barcode80]

Hum... and is it reliable? I... whaaaa? $1.80 shipping? o.O

erm... thanks?

You aren't going to find anywhere that charges any less for shipping. There is a finite minimum shipping cost, no matter how small the order. Best to order with a few other items.

[Kli Klis]

No! I know! It wasn't an expression of "it's too much" it was an expression of being flabbergasted with how unrealistically CHEAP the shipping is! o.O

[DavenPaget]

Tayda is truly cheap ! But some things there , to be said , should be avoided like sex with an Ethiopian Travestite .
I'm talking about their PT2399 , it's cheap but i heard 1 in 10 only works properly for our use , seems like we need some tuning 

[Kli Klis]

BTW , tayda stocks them at 0.46$ 

For the record. After searching for about half an hour, I still haven't found them. They only have UNswitched jacks. If you do have a link, please be kind enough to post it...

[slacker]

I guess he means these http://www.taydaelectronics.com/servlet/the-1954/6.35mm-1-fdsh-4%22-Stereo-Insulated/Detail it says unswitched but the picture is of switched, who knows what you actually get.

[DavenPaget]

I guess he means these http://www.taydaelectronics.com/servlet/the-1954/6.35mm-1-fdsh-4%22-Stereo-Insulated/Detail it says unswitched but the picture is of switched, who knows what you actually get.

I don't know whether is it switched or unswitched ( anyway , i have no idea )
And yes i was referring to that .

[Barcode80]

http://www.mammothelectronics.com/4SJK103S-p/610-1005.htm

[teej212]

intensity on the SM is an input gain pot- no need to add an exp pedal, just add a volume pedal infront of it.