Buzz Coils: What to do if the Buzz stops here.
Buzz coils were used extensively on small engines for ignition of days gone by and by Henry Ford on the famous model T. They employed a battery and a timer switch to fire the spark plug when the switch is closed. They unlike most ignition systems produce a spark as long as the timer switch is closed. Most ignition systems produce a single spark when the points open. The Model T Ford used a buzz coil on each cylinder and a low tension timer to energize the buzz coils in some sequence hopefully resembling the firing order within a few degrees. Here is some information to help get the spark back if your buzz coil decides to buzz off.
They employ a set of primary and secondary windings in a step up configuration like a magneto or other ignition coil. The necessary changing field in the iron core is produced by passing current through the primary windings from a battery through a set of contacts on top of the iron core. When power is applied, current flows through the primary windings creating magnetic force on the top of the iron core that pulls the contacts apart interrupting the current flow causing the magnetic field in the iron core to collapse inducing a high voltage in the secondary windings. When the magnetic field is off, the contacts come back together completing the circuit and the process repeats at a rapid rate causing the familiar buzzing. A condenser (capacitor for electrical engineering majors) is connected across the contact points to reduce sparking and intensify the spark.
Problem areas for buzz coils are like many other ignition components. The first to address with a no go is the contact points. Over time they can become pitted and corroded and need to be dressed smooth and set to the proper clearance and tension. The tension determines the amount of primary current to pull them apart. Insufficient tension may cause insufficient primary current to make a spark. Excessive tension will cause battery drain and premature points wear. A bad condenser will cause a weak spark and excessive sparking at the points.
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