Low cost rev counter that works.

[jacw]

Having just bought and fitted a low cost 52mm rev counter off Ebay  https://www.ebay.co.uk/itm/334082240200  which works I thought others might be interested.
At the back of the rev counter is a switch for 2,4 & 8 cylinders. Having fitted it the needle fluctuated a bit so a quick google found a useful little video  https://www.youtube.com/watch?v=-6j3glUtecY   which shows how to fix the problem. 
Back to Ebay to buy
https://www.ebay.co.uk/itm/203327665249?var=503711022049 for £2.45 for ten 10K Ohm 0.5 W fixed resistors.
Fitted the resistor as per the video and now a perfectly smooth needle.
My ignition set up is 123 electronic with twin coil. I think I read that Rusty has the same set up.
Hope this helps and by the way I am not technical.
jacw

[Minijohn]

That's really interesting - I'd like a tacho in my car.

My car has the factory electronic ignition and I've no idea where to connect the tacho - anyone have any idea?