Energy Hall’s Machinery 9

This device is the oldest dynamo in the Museum of Technology’s collection, as it dates back to 1867.

Dynamos convert mechanical rotation into electrical energy. You may recognize them by their other name, a generator. Their output was generally low, but the Siemens model was one of the first to be used in industry. The H-arm dynamo is an example of an electromagnetic dynamo. Prior to this type of model, permanent magnets had been used in dynamos to generate a magnetic field. When the device was cranked and the metal arms were rotated in combination with the other components in the dynamo, it would produce an electric current that would magnetize the iron H-arm. This technique made the dynamo self-magnetizing and when the rotating ceased, the device was also self-releasing. Today’s technology giant Siemens takes its name from the inventor of this device, entrepeneur Werner von Siemens (1816 – 1892), who founded Siemens & Halske, a company specializing in telegraphs and electrical equipment.