Modify VIIB vibrato to square wave?

[neiltheseal]

Hey everyone

I came across this video below thich sounds pretty cool. It's for a TC Electronic Tailspin but I'm pretty sure that is a clone of the Boss VB-2.

Does anyone know how I can achieve the mod in the attached video and apply this to the VIIB? Specifically I'm interested in the train mod. It sounds like the waveform has been adjusted but I might be wrong.

Viib Vibrato schematic is here

The bike mod to me sounds like increased depth and delay time but the train mod has me curious.

Thanks in advance.

 

[neiltheseal]

This guy seems to have done the same mod to his tailspin but I can't figure out how to apply that to the VIIB.

Not sure where I should put the potentiometer since there is no voltage regulator.

I've had the alligator clips out this afternoon but am not having much luck.