Being used to two separate output volume dials in the Fractal FM3 I designed and built my own pedal expression dial
I use the main output dial for one lane that goes to the PA and the expression dial that I assign to a different lane that goes to anything I would like to feed on stage. In most cases my own monitor and in the near future maybe in ear monitors.
The potentiometer is a dual gang (stereo) 50K linear type. One pot controls the expression function. This is totally passive and the lugs are directly connected to the TRS lugs on the output jack.
The other pot controls the LED dial as a visual reference. On stage you will always see if your second lane is up or not. When the volume is completey closed, the red LED at the bottom will light up, showing you that the unit has power. Once you turn the dial and the first volume indicator LED lights up, the red LED turns off. Then the volume LEDs are your power indicator. The LEDs are powered by two mirco controllers… The pedal is 9V battery or 9V DC powered and the jack will accept any Boss type power supply (negative tip). The circuit has reverse polarity protection. It also has a battery on/off switch. If you use battery only, you can switch the power off so the battery does not drain. The DC jack is switching, so the battery will be disconnected when a plug is inserted.
To be clear - this is a passive expression control and it will always work. The power is used only for the indicator LEDs
This unit is a prototype. The Hammond case is rattle can finished and I polished the front a little too long. You can see the metal of the case is shining through on the third last LED. It will be up for sale in Germany soon.
Here is a short video: https://youtu.be/YE7-OUY_Rmk
I am currently working on a pedal VU-Meter to help level the volume of presets. I will post this here too.
A dedicated 230V properly filtered power supply with a 12V 3A output for the QC and three additional 9V outputs for pedals totalling 1,2A is also almost ready and I will post info on this gadget soon too.