MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

Help me wire a pot instead of an on/off/on switch
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Help me wire a pot instead of an on/off/on switch
rurs
I'm trying to make a little expander for a Mutable Things Ears, to enable adjustment of the envelope follower.
From the factory, there are jumpers for making rough settings, but pichenettes has mentioned using pots instead, without going into details.
I've tried with standard 3 leg pots, but no matter what way I wire them up, only about half the travel has any effect.
Is there anything obvious I'm missing, or maybe I need a different type of pot?
Any thoughts or hints?
steviet
What value pot are you using?
BugBrand
Checking the schems it looks like you'd want to physically replace the resistors that the switches are selecting.

For Attack - ignore R25/R26 and replace R29 with a 100k (Log probably)
For Decay - ignore R23/24 and replace R28 with something like a 500k or 1M (Log again)

I reckon at least - speculation!
rurs
steviet wrote:
What value pot are you using?


I've got 1M logs for attack and release, and 1M Lin for gate detection.

pichenettes wrote:


Something worth noting for the DIYers/modders: if you decide to build an expander for it, you are not forced to use switches - you can also wire a 470k or 1M pot in such a way that it'll go smoothly between the lowest and largest setting.


In general, where would you wire the wiper to, for example?
rurs
BugBrand wrote:
Checking the schems it looks like you'd want to physically replace the resistors that the switches are selecting.

For Attack - ignore R25/R26 and replace R29 with a 100k (Log probably)
For Decay - ignore R23/24 and replace R28 with something like a 500k or 1M (Log again)

I reckon at least - speculation!


I hope that won't be necessary!
guest
BugBrand is correct, you will have to remove those resistors. if you dont, they set the max values of decay/attack, as they are not switched, and are permanently wired into the circiut. even if you like the max values they set, they will limit the range a pot can control things. the reason is, they will be in parallel with the pot, and as you turn the pot and the resistance increases to get closer to the value of those resistors, the pot will have les and less effect. after the resistance of the pot increases to larger than the fixed resistor, then the pot no longer effects anything (or very minimally so).
rurs
guest wrote:
BugBrand is correct, you will have to remove those resistors. if you dont, they set the max values of decay/attack, as they are not switched, and are permanently wired into the circiut. even if you like the max values they set, they will limit the range a pot can control things. the reason is, they will be in parallel with the pot, and as you turn the pot and the resistance increases to get closer to the value of those resistors, the pot will have les and less effect. after the resistance of the pot increases to larger than the fixed resistor, then the pot no longer effects anything (or very minimally so).


Thanks for the explanation. They're all SM unfortunately, so I don't fancy getting stuck in with my current iron.
Suppose I'm happy with the max values these resistors set, is there an obvious way to wire a pot to the jumper headers to give some control over the values?
guest
put the pot between pins1,2 on the attack, and pins2,3 on the decay. if you use 1M on the decay, the last half of the pot wont do too much. if you use a 500k pot, the full range will have effect, but longest decay will be half as long as with the 1M pot.

you only need to get the resistors off, which might not be too hard. or, you could take an xacto knife and cut the trace next to the resistor.
rurs
So I've tried that, still not terribly satisfactory.
I'm struggling to visualise how it can actually work...Does this sound right so far: the equivalent of jumper off would be with the pot at max, ie nothing flowing between the pins.
To get the minimum/fastest/lowest value, the pot should be at minimum.
But then where does the mid value fit in...

Is that why you suggested only using 2 legs from the pot, the wiper and one other?
guest
you can use only 2 legs, or tie the 3rd leg to the wiper. both will behave identically. the minimum time is set by the resistor going to pin1 (accent) and pin3 (decay), and the max time is set by the fixed resistor. the pot will sweep between these two values. if you want a different behaviour, you will have to either cut a trace, or remove a part.
rurs
OK, I understand it now, and it does work. It only really made sense once I attached the gate detector, to pins 1+2.

Thanks for taking the time to walk me through it, and expand my knowledge.

For anyone else interested in this as a first project, here's what I used:

Pots, 3 of these: https://www.thonk.co.uk/shop/alpha-9mm-pots-vertical-t18/

Or switches, these: https://www.thonk.co.uk/shop/sub-mini-toggle-switches/

Knobs: https://www.thonk.co.uk/shop/micro-knobs/

Cable: https://hobbycomponents.com/cables/114-20cm-solderless-dupont-jumper-b readboard-wires-40-cable-pack.html

I found I could remove one of the plastic caps of the dupont cable, and then the exposed terminal would slide onto the lugs of the pots or switches, and could be held in place with a dab of solder. The other end then slides perfectly onto the jumper pins.

MUFF WIGGLER Forum Index -> Music Tech DIY  
Page 1 of 1
Powered by phpBB © phpBB Group