i thought i'd copy this here in a separate thread, so more people might see it and it's easy to link back to. it seems to be a pretty perennial topic of discussion
it only uses one block, so it'll work on the FM3
put a synth block into your preset before the amp block. i like to have it in parallel with the main line. set mix to 100% and bypass mode to "mute fx in" in case you want to bypass it
you only need to use one voice, so set voice 1 to a triangle wave, set track to "off" and shift = 7 (also try 19 which sounds great on low notes). i have the block level on mine set to about -18db, but tweak that to taste.
View attachment 114711
attach a controller to voice 1 level. this can be an expression pedal (nice, for continuous control), or it can be a control switch. i have a control switch for mine (set up as an "FC per preset override) and i have set the "attack" parameter to about 600ms and the "release" parameter to 50ms. (this is in the parameter linking window). this is to make the effect fade in gradually. i like it on a momentary switch, rather than latching. adjust the attack value to taste.
View attachment 114712
now you need to attach the pitch controller to the "frequency" parameter for voice 1. leave everything at default, except
"start" = 30.3%
"mid" = 62%
"end" = 93.7%
this makes the frequency of the synth track the pitch follower (the pitch of any note you're playing)
View attachment 114713
you may need to tweak these values, as i've come across some units that seem to be calibrated very slightly differently
hope that helps. let me know if you have any questions
quick demo