Your a masochist. 8^) Most of the laws and principles were covered in the first semester of Electronics (DC Theory) I took many years ago. D'Arsonval movements were not the easy part of the course. The text we used was "Electrical Principles of Electronics" by Gillie.

I'm thinking an easier approach would be to find a Tachometer kit, it should provide a schematic. That would provide a good starting point to decipher the Pontiac tach. I did a search on that auction site and found this;

http://cgi.ebay.com/ebaymotors/VINT...000QQptZSnowmobileQ5fPartsQ5fAccessories

For what those tachs are selling for on ebay some effort to salvage that one is worth it. I have some doubts about what the water may have done to the little coils.

Larry

I don't own a vehicle that isn't old enough to drink.