thanks for that, I tried a Chinese cheapo and it worked like that but only gave a sample of the revs every 4 seconds.
ive bought a german mmb tacho and am in the middle of wiring it up after numerous emails to vape (who bought out powerdynamo) - waste of time.
I emailed powerdynamo and they came up with the right info. just about to wire it up now.
I just wanted to know what revs i'm doing so I can fool around with pipes ports etc.
edit got it working. finally
doesn't look too out of place..