Synching a Vortex?

[gstopp at fibermux.com]

     I think you are on the right track...
     
     It is distinctly possible that the Vortex tap footswitch input is 
     looking for a short to ground as the trigger event, in which case you 
     could skip the relay idea and just use the transistor to ground the 
     input (like a Moog S-trigger). To turn on the transistor you could use 
     a voltage trigger from a MIDI clock-to-voltage pulse converter, or 
     like you say derive a pulse from an audio event such as a drum hit.
     
     Converting the audio pulse to a voltage trigger can be done with an 
     envelope follower plus a comparator. Actually for such a specific 
     application you can probably throw together a simple 
     diode/cap/resistor peak detector into an op-amp into the transistor 
     and be done with it. Probably you'll need a 10x preamp on the front 
     end. It might have to be tweaked to the specific drum sound that you 
     use, but since the Vortex is expecting a "sloppy" pulse like a human 
     foot on a switch, it probably doesn't care too much about pulse 
     duration.
     
     The way I'd figure this out is with a protoboard, an assortment of 
     components, and a scope. Hey I have a Vortex now, maybe I'll check 
     this out some time (next week at the soonest...).
     
     A couple weeks ago I built a MIDI-clock to voltage pulse divider 
     circuit on a single chip, but that's another story...
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: Synching a Vortex?
Author:  "Arnim X. Sauerbier" <arnims at usa.globelle.com> at ccrelayout
Date:    1/30/97 6:06 PM


Hi folks!
     
Not a synth question, but a musical DIY topic nonetheless:
     
I've got a Lexicon Vortex (worth the $149 sale price IMHO).  It lets the 
user set delay times by tapping a 'delay/tap' button twice.  The box has 
no MIDI interface, but I'd like to sync the delays to my MIDI sequences!
     
I was thinking of the following hack:  use one of the outputs of my drum 
machine as a click, then build some kind of circuit that closes the 
contact of the 'tap' switch whenever a voltage peak (from the drum 
machine) is detected.  
     
What would such a circuit look-like?  Perhaps a transistor that triggers 
a relay that closes the 'tap' button?
     
What would you do?  Any other solutions that wouldn't involve using-up an 
output on my Drumstation?  
     
Thanks!  Sorry for my glaring ignorance. 
------------------------
Arnim