Quote Originally Posted by mister_e View Post
o.k. ONCE again

which car model, brand, year?
Probably not going to mean much to you.

Make and Model: Vauxhall Corsa
Year: ? no idea - will ask him.

All I had to go on was:
My wife Jenny has a Vauxhall Corsa that had just a cable driven speedo. I've gotten hold of an insrtumanet cluster that has tacho and speedo, but the speedo isn't cable, it's electrical. The tach works fine, but the rotary encoder I've picked up (which is supposed to be the right one) is giving only half the number of pulses required by the speedo, i.e. the speedo is reading half the actual speed.
The question I have is....."Is there a simple way to double the number of pulses to the speedo...like a frequency doubling circuit" ??

I believe the unit I have works optically...disc with 10 light dark changes per rev. The easy answer would be to put a disc in the unit with twice the number of segments, but it's not able to be disassembled easily.