The term 'dynamos' refers to three different types of machines. The first is a 'DOER, ' which is a type of machine that performs a specific task. The second is a 'FIREBALL, ' which is a type of GENERATOR that produces electricity by burning fuel. Finally, the third type is a 'GENERATOR, ' which is a device that converts mechanical energy into electrical energy. All three of these machines are powered by dynamos, which are electric motors that convert mechanical energy into electrical energy.