Hi Russell,

The tachometer is on a home-made engine and it DOES have spark ignition. The points are quite close to the hall sensor. I do have plans to get rid of the points and condensor and replace them with a slightly more modern setup that also uses a hall sensor.

The code I'm using only updates the LCD every second, so although this doesn't prevent the value from jumping all over the place, it does mean the value is always readable. What exactly do you mean by 'filtering' the RPM values?

Warren