1. Use Ernie Ball Guitar Pedal
The MOTM-850 manual that I have states:
"If you have a passive volume pedal (like the Ernie Ball), these will NOT work".
This is bunk. I have been using an Ernie Ball pedal with both Roland and Yamaha keyboards for 20 years. The same pedal works just fine with the MOTM-850. The trick is to use an insert cable.
The phone plug that goes into the MOTM-850 PEDAL input has three conductors: tip, ring, and sleeve. Create a lead that connects the tip and sleeve of the PEDAL output to a two conductor phone plug (call this lead AMP). Create a second lead that connects the ring and sleeve of the PEDAL output to another two conductor plug (call this lead INST). Connect the first lead to the AMP jack on the pedal. Connect the second lead to the INST jack on the pedal.
The output from my pedal is a bit hot. Even without the JMP3 jumper I get about 6.5 volts out with the pedal all the way down. This is not a problem since it is well within the input voltage limit of any module in my system. I can always tone down the voltage with the RANGE control on the MOTM-850 if I need to.
My Ernie Ball pedal is smooth like butter, I can't imagine using anything else with my synth. It has a pot on the side that modifies the resistance contour as the pedal is swept. This is very handy for tweaking the pedal response from log to linear to anti-log.
Sound samples using an Ernie Ball guitar pedal with the MOTM-850 pedal interface can heard on the TLN-132, TLN-428, and TLN-442 module pages.
The truth is out there: you can use your guitar pedals with the MOTM-850.