The secondary winding is made up of thousands of turns of hair-fine wire, wrapped around a laminated steel core. As the magnetism generated by the current flowing through the primary winding collapses as the points open, it cuts across the secondary and induces voltage into each turn of wire. Several thousand volts are created, enough to jump the gap of the spark plugs. This process is repeated each time the points close, then open- - - - -one for each compression stroke of the engine. That's why the distributor must be timed correctly, so the spark happens just as each piston reaches the top of the compression stroke, with the right mixture of fuel and air in the combustion chamber.
The condenser acts as a shunt to minimize damage to the points created by the magnetic induction in the primary winding- - - -which momentarily spikes the primary voltage from 6 or 12 volts to a hundred or more.
Jerry
