Well I guess the title kind of gives it away but I need some help with my tachometer.
A little bit of background first I have built the vibrating pedals the wind simulator and even troubleshooted and older tach and got it working. For the record it turned out my very old 8000 RPM rev counter just needed to be hooked up directly to the Arduino board with that would be little circuit included so I ran 12 volts directly to it and then from the Arduino and 9 signal wire directly to the tack and bingo it work absolutely perfect. Now on to the new one
I recently purchase the motorcycle cluster and hopes that I could use the rev counter speedometer and possibly the temperature gauge. I am using the little circuit with the tip120 and it is fairly straightforward wiring so I don't think I could have messed it up however I was assured that these gauges work and have no reason to doubt that they do I cannot get the gauges working however in any way I have noticed if I disconnect the ground while everything else is connected up the tach jumps up a little bit. It is a simple 3-wiretach .
The cluster is from a Honda vtr1000.