On Tue, 17 Apr 2018 13:14:42 +0100
Adrian Caspersz wrote:

On 17/04/18 10:55, Graeme wrote:

Back to the Morris.Â* I have an ammeter, 30-0-30, and the dynamo is
rated 13.5v, 22 amps.Â* Still +ve earth.Â* What I don't have is
suitable brown cable, and there seems to be a lot of conflicting
advice.

Go for some kind non-invasive DC hall effect sensor, and log the
readings digitally?

That was my first thought, but he wants to use the period meter so
you'd have to modify that so you could drive it with e.g. an Arduino.