I worked for a company that made horns many years ago (Spartan Mfg), now out of business. At the time I had a Puch motorbike (sold by sears) from the mid-60's. I wanted a horn on it so I had the guys do an electronic signal on the magneto so I could design an AC horn for it (a dc horn won't work). Once I get the Simplex running, I'll try to do the same thing.
Mike Sal