The Model T had 4 buzzer coils in a box on the firewall...
There was a roller inside a small can on the end of the camshaft..The can was connected to the spark lever on the steering column so it could be advanced and retarded....As the roller turned inside the can it connected each coil in turn to fire the spark plug...The coils were not activated until the roller contacted the metal piece on the inside surface of the can...
Last Model T truck I bought in 1951 cost me $2.50....Sold it for $5, a 100 % profit...
The coil box was wood and after 50 years or so there were spark tracks all over the inside of the box, looked like termites were in there...
Sometimes you could turn the key on when one of the coils was activated, and the engine would start all by itself....