Construction of a Simple Dynamo

Construction of a Simple Dynamo


Construction of a Simple Dynamo


Abstract of Construction of a Simple Dynamo

Dynamo is the name given to D.C generators. In the past, alternating current generators are not common. Voltages are generated using dynamo where the voltage generated are later converts to A.C. The dynamo I constructed had a permanent magnet. This magnet in the form of circular disc which revolves around turns of coil that is wound on a u-shaped former. When the disc is rotated the magnetic field North / South pole cuts lines of force and e.m.f is generated.



Chapter One of Construction of a Simple Dynamo



The word Dynamo from “(from the Greek word dynamics: meaning power) was originally another name for an electrical generator and still has some regional usage as a replacement for the word generator. After the discovery of the AC generator and that alternating current can be used as a power supply. The word dynamo became associated exclusively with the communicated direct current electric generator while on AC electrical generator using either ship rings or rotor magnet would become known as an alternator.

A dynamo is an electrical generator that produces direct current with the use of a commutator. Dynamos were the first electrical generators capable of delivering power for industry and the foundation upon which many other later electric power conversion devices were based including the electric motor, the alternating current alternator and the rotary converter. Today the simple alternator dominates large scale power generation for efficiency, reliability and cost reasons.

A dynamo has the disadvantages of a mechanical commutator besides; converting alternating current to direct current using power rectification devices (vacuum tube or more recently solid state.) is effective and usually economical.

The faraday disk was the first electric generator. the horseshoe shape magnet (A) created a magnetic field through the disk (D) when the disk centers toward the rim. The current flowed out through the sliding  spring contact m, through the external circuit and back into the centre of the disk through the axle. The operating principle of electromagnetic generators was later called Faraday’s law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. He also built the first electromagnetic generator, called the Faraday- disk, a type of homopolar generator, using a copper disk rotating between the poles of a horseshoe magnetic. It produced a small DV voltage. This was not a dynamo in the current sense, because it did not use a commutator. This design was inefficient, due to self counseling counter flows of current in regions that were not under the influence of the magnetic field. While current was induced directly underneath the magnet, the current would circulate backwards in regions that were outside the influence of the magnetic field. This counter flow limited the power output to the pickup wires and induced waste heating the copper disk later, homopolar generators would solve the problem by using an array of magnets arranged around the disk perimeter to maintain a steady field effect in one current flow direction.

Another disadvantage was the output voltage was very low, due to the single current path through the magnetic flux. Faraday and others found that higher, more useful voltages could be produced by winding multiple turns of wire into coil. Wire windings can conveniently produce any voltage desired by changing the number of turns? So they have commutator to produce direct current. Independently of Faraday, (The Hungarian) Anyas Jedlik started experimenting in (1827) with the electromagnetic rotating devices which he called electromagnetic self-rotors. In the prototype of the single pole electric starter, both the stationary and the revolving parts were electromagnetic.

About 1856 he formulated the concept of the dynamo about six years before Siemens and Wheatstone but did not patent it as he thought he was not the first to realize this. His dynamo used, instead of permanent magnets, two electromagnets placed opposite to each other to induce the magnetic field around the rotor, it was also the discovery of the principle of dynamo self excitation.


Before the connection between magnetism and electricity was discovered, electrostatic generators were used. They operated on electrostatic principles such generator generated very high voltage and low current. They operated by using moving electrically charged belts. The charge was generated using either of two mechanisms. Electrostatic induction and the turboelectric effect. Because of their inefficiency and the difficulty of insulating machines that produced very high voltages, electrostatic generators had low power ratings and were never used for generation of commercially significant quantities of electric power.

Currently, the negative impact of fossil fuel to our environment and the increasing rate of global warming and green house gases has made our environment unsafe and these is need to look for an alternative source of energy from natural source that can be environmentally friendly and yet still solve the energy need to our population. Also the epileptic power supply in developing countries has necessitated for another power source that will be constant and readily available.


The principle of operation and the technical know-how of simple dynamo helped a lot in the application an construction of wind turbine and the larger hydro-electric that has contributed immensely to the generation of very huge electrical power source to the national grid source.  The objective of this project was to design and construct a simple dynamo using as far as possible locally available materials which would provide cheap means of generating energy to power source of our electronics. The objectives of the project therefore are to design and construct a simple dynamo from electromagnetic induction mechanism.


The work will help solve the energy need of our society as it will generate alternative energy source. Specifically, many people benefit from this work as it provide simple, mobile and alternative sources of power to cyclist, part of camps at any given time or place.

Finally, this work has help to enlighten the society on how to utilize locally available electronics in construction of dynamos for the production of light.


This work will try to design and construct a simple dynamo using simple electronic components readily available in our local markets.