Vortex Sound Research

I'm looking for a trigger I can put on the batter head of a kick drum which will clock an arpeggiator. The keyboard (juno60) is non midi. I went to a local music store and hooked up a trigger (roland rt30k) to the arp cv in on a moog grandmother (directly with patch cable). Oddly, the arp advanced every second time I hit the cone on the trigger. I was told the trigger sends velocity info and it normally goes into a module via trs cable so I'm guessing that accounts for the issue. Can anyone suggest that simplest, cheapest way to trigger cv gear with acoustic drums?