Topic: Who knows the origin of the dual output coil in a waisted ignition system?

[Deltarider]

I happen to love simplicity. The more I have looked at our ignition sytem, the more I admire it. I've searched the internet but I have not found an answer yet. Who was the first who thought of it and what vehicle had it first? I have two candidates: carmaker Citroën and Harley-Davidson. Does any of you have the answer or can tip me where to look?

[69cb750]

Harley used a single coil with two leads in the 20's
Indian used a single coil with one lead and distributor.

[HondaMan]

It was said to have come from the first shipboard "petrol-fueled" (i.e. early gasolines) engine designs of early internal-combustion types that ran at speeds like 600 RPM. I found that reference in a very old, tattered book about old airplane designs, read it around 1972 or so when I had just opened my shop. It was written by a British author, about British accomplishments. Danged if I remember the title, though...

These coils actually run opposite phases as they discharge: for example, if it was a 1-4 coil, when the spark starts it jumps from the plug tip to the ground on one side, and the opposite polarity (and direction) on the other plug. It oscillates between 3 and 6 times in our bike's versions, per oscilloscope traces I made back when I wrote my first book on the 750. It oscillates many more times than that, but without enough energy to jump the plug gap. The condensors help damp out the leftover energy then to allow for quicker recharge for the next time around.

[scottly]

The issue with a dual output coil is that one terminal produces an reverse polarity spark; with our stock coils, cylinders 1 & 2 always have the proper polarity, while 3 and 4 always have reverse polarity. A reverse polarity spark requires 20 to 40% more voltage than normal polarity.
BTW, the term is wasted, as in to throw away, not waisted, as in a person's middle torso.

[Don R]

 Scottly, have you ever seen a Gerex spark on an oscilloscope? If a stock coil oscillates between wires, I wonder what the Gerex actually does? 

[rocket johnny]

look up charles kettering ,,  he did a lot of work on coils and did the first electric starter