please help me understand this device, you have to select a destination, I’m guessing something else that modulates like an LFO? but I don’t understand why you have to select an instrument. is it - everytime the instrument passes on the pattern, then that’s the trigger?
I read the renoise wiki help on it but I still don’t understand 
Basically, the Key Tracking Device allows you to convert note information into a trigger for other things. You could link it to a filter, for example, which is very common in synths where you want to gradually filter the sound in some way as you progress through the octaves. But you can really do whatever you want, just be creative. Play around with the different parameters to fine-tune the range of the device. Maybe you have some distortion on a bassline, but when playing notes above a certain pitch you want to reduce or disable the distortion, etc.
Here’s an example that I posted in another thread recently:
http://illformed.org/temp/note_synced_lfo.xrns
In this example I am simply retriggering the LFO whenever a note is played. I have set the key track device’s min and max sliders to 0, so that it will reset the LFO at position 0 every time. If I were to set minimum to 0 and maximum to a higher value, lower notes would retrigger the LFO at a position closer to 0, while higher notes would retrigger it at a higher position.
Another possitiblity is that you could vary the LFO speed based on the note, which is quite handy for creating dubstep style bass: (Crappy example from a silly drunken night tracking weeks ago, but you get the idea)
http://illformed.org/temp/keytrackbass.xrns
Pretty fun device which I use alllll the time with my LFOs 
damn that’s awesome thanks alot for that dblue !! wicked sounds too
I just updated the bass thing to simplify it a bit. Re-download if you wish. Definitely more of a proof of concept than a useful sound, haha.