Classic Techniques
Dynamos, like magnetos, are unfairly blamed for all kinds of electrical problems. The dynamo can be a very reliable device, but as time has gone by so owners have found novel ways of abusing and misusing these trusty devices.
The first dynamo was demonstrated by Faraday in 1832. It used fixed magnets to create the magnetic field and the voltage was varied by how quickly the generating coil rotated in the magnetic field. The first breakthrough in creating a practical dynamo for industrial application was replacing the fixed magnets with an electrical-magnetic (field) coil, powered by a separate small dynamo. Then came the discovery in the 1850s that a dynamo could self-generate. They noticed that with the dynamo disconnected and the field coil disconnected a small residual magnetic field in the dynamo still generated a small output voltage. Connecting the small output voltage to the field coil increased the field strength which increased the output voltage, which created a cascade effect (self-generate) until a balance was achieved.
By the start of the 20th century, when innovators were fitting electrics to motor vehicles, the dynamo was well understood. However most dynamos were driven by a constant-speed prime mover, like a steam engine, and the output could be manually connected and adjusted to match the load. The new challenge was a prime mover that was constantly changing speed and the load could change faster than could be manually adjusted.
The following is a practical guide to conducting checks and limited repairs before calling in the professionals. It’s a guide for the things to look for, it is not definitive and no doubt other dynamo dabblers will identify further issues.
NAMING OF PARTS
THE ARMATURE is the rotor that carries the coils of wire which generate the current. The coils of wire are joined together like a daisy chain, the end of one coil and the start of the next are joined at the commutator segments. The coils are buried in the laminated body of the armature and insulated from the body. The thin steel laminations of the body reduce electrical / mechanical losses and increase the output
creates the
