Adding expression jack for Tremolo speed



Moderators: PumpkinPieces, Gunner Recall, metalmariachi

Forum rules
The DIY forum is for personal projects (things that are not for sale, not in production), info sharing, peer to peer assistance. No backdoor spamming (DIY posts that are actually advertisements for your business). No clones of in-production pedals. If you have concerns or questions, feel free to PM admin. Thanks so much!

Adding expression jack for Tremolo speed

Postby Faldoe » Wed Jul 19, 2017 1:43 pm

I have a Demeter Tremulator clone that I built. Speed pot is 500K Lin.

How would I wire an expression jack so that when the exp pedal isn't plugged it, the speed control works as normal?

I can't just wire the expression jack parallel with the stock pot, right? Cause if I do the the exp pedal won't do anything to alter the values cause the stock pot will still be connected

Are there plus switching jacks that also have a make/break connection lug?

I was thinking of wiring the stock pot's wiper to the jack so when the exp pedal is connected, the stock pot wiper is disconnected​ and when the exp pedal is unplugged the stock pot wiper is reconnected.

Make sense?
Faldoe

User avatar
FAMOUS
FAMOUS
 
Posts: 1809
Joined: Tue Jul 29, 2014 10:15 pm

Re: Adding expression jack for Tremolo speed

Postby crochambeau » Wed Jul 19, 2017 2:15 pm

Faldoe wrote:Are there plus switching jacks that also have a make/break connection lug?


Yes. It so happens I've been looking into installing an expression jack that will take priority over the panel mount frequency control on the RMA Monobius (how's that for back door spamming? Sorry!). The criteria for this working is that one leg of the potentiometer being replaced MUST connect to ground, as the shaft connection of the jack is not switched, and is generally mechanically fastened to the chassis.

Switchcraft 114BX is a TRS female 1/4" jack that has normalling (switch closed until plug is inserted) contacts on both the tip and ring. You simply wire your "high" and wiper legs of the pot through the switched contacts so the pot is taken out of circuit when an external pot is plugged in.

If you have a circuit node at "low" instead of ground I've seen plastic case switching jacks that will interrupt the shaft as well, but I have no part number handy.
crochambeau

User avatar
FAMOUS
FAMOUS
 
Posts: 1097
Joined: Mon Jul 20, 2015 12:49 pm
Location: Cascadia

Re: Adding expression jack for Tremolo speed

Postby Dr Satan » Fri Jul 21, 2017 1:39 pm

https://www.tubedepot.com/products/505-1-4-jack This and what Crochambeau said. If your EXP pedal doesn't have a switch to reverse the outer lugs of the pot, you may want to mod it too as it is common for LFO speed controls to have a reverse log taper.
Dr Satan

User avatar
committed
committed
 
Posts: 181
Joined: Thu Aug 25, 2011 4:11 pm
Location: South of the ATL

Re: Adding expression jack for Tremolo speed

Postby ianmarks » Sun Jul 23, 2017 12:27 pm

Here is a drawing for reference. Jsut be sure to check the datasheet for whatever jack you buy so you know what lugs switch when plugged or unplugged.

http://www.sonelec-musique.com/images/e ... xterne.gif
ianmarks

involved
involved
 
Posts: 70
Joined: Thu Mar 22, 2012 5:34 pm


Return to DIY Effects



Who is online

Users browsing this forum: No registered users and 1 guest


Sponsored Ad. (Please no inflated/repetitive clicking. Thanks!)

Advertisements help support ILF


ilovefuzz.com is not responsible for user-submitted content. Users participate at their own discretion and risk.