Contents

 Introduction

 Etymology

 Description

 Commutation

 Excitation

 3History

 Induction with permanent magnets

 The first dynamos

 Dynamo self excitation

 Practical designs

 Rotary converters

 Historical uses

 Electric power generation

 Transport

 Conclusion

 Reference

1
Introduction

Dynamo

"Dynamo Electric Machine" (end view, partly section, U.S. Patent 284,110)

A dynamo is an electrical generator that creates direct current using

a commentator. 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 simpler alternator dominates large scale power generation,

for efficiency, reliability and cost reasons. A dynamo has the
disadvantages of a mechanical commentator. Also, converting
alternating to direct current using rectifiers (such as vacuum tubes or
more recently via solid state technology) is effective and usually
economical.
2
The word dynamo (from the Greek word dynamis (δύναμις), meaning
force or power) was originally another name for an electrical generator,
and still has some regional usage as a replacement for the word
generator. The word "dynamo" was coined in 1831 by Michael Faraday,
who utilized his invention toward making many discoveries
in electricity (Faraday discovered electrical induction) and magnetism. 

The original "dynamo principle" of Werner von Siemens referred only to

the direct current generators which use exclusively the self-
excitation (self-induction) principle to generate DC power. The earlier
DC generators which used permanent magnets were not considered
"dynamo electric machines". The invention of the dynamo principle
(self-induction) was a huge technological leap over the old traditional
permanent magnet based DC generators. The discovery of the dynamo
principle made industrial scale electric power generation technically and
economically feasible. After the invention of the alternator and
that alternating current can be used as a power supply, the
word dynamo became associated exclusively with the commutated direct
current electric generator, while an AC electrical generator using
either slip rings or rotor magnets would become known as an alternator.

A small electrical generator built into the hub of a bicycle wheel to

power lights is called a hub dynamo, although these are invariably AC
devices, and are actually magnetos.

3
Description

The electric dynamo uses rotating coils of wire and magnetic fields to
convert mechanical rotation into a pulsing direct
electric current through Faraday's law of induction and Lenz's law. A
dynamo machine consists of a stationary structure, called the stator,
which provides a constant magnetic field, and a set of rotating windings
called the armature which turn within that field. Due to Faraday's law of
induction the motion of the wire within the magnetic field creates
an electromotive force which pushes on the electrons in the metal,
creating an electric current in the wire. On small machines the constant
magnetic field may be provided by one or more permanent magnets;
larger machines have the constant magnetic field provided by one or
more electromagnets, which are usually called field coils.

4
Commutation

The commutator is needed to produce direct current. When a loop of

wire rotates in a magnetic field, the magnetic flux through it, and thus
the potential induced in it, reverses with each half turn, generating
an alternating current. However, in the early days of electric
experimentation, alternating current generally had no known use. The
few uses for electricity, such as electroplating, used direct current
provided by messy liquid batteries. Dynamos were invented as a
replacement for batteries. The commutator is essentially a rotary switch.
It consists of a set of contacts mounted on the machine's shaft, combined
with graphite-block stationary contacts, called "brushes", because the
earliest such fixed contacts were metal brushes. The commutator
reverses the connection of the windings to the external circuit when the
potential reverses, so instead of alternating current, a pulsing direct
current is produced.

5
Excitation

The earliest dynamos used permanent magnets to create the magnetic

field. These were referred to as "magneto-electric machines"
or magnetos.[4] However, researchers found that stronger magnetic fields,
and so more power, could be produced by using electromagnets (field
coils) on the stator. These were called "dynamo-electric machines" or
dynamos. The field coils of the stator were originally separately
excited by a separate, smaller, dynamo or magneto. An important
development by Wilde and Siemens was the discovery (by 1866) that a
dynamo could also bootstrap itself to be self-excited, using current
generated by the dynamo itself. This allowed the growth of a much more
powerful field, thus far greater output power.

Self-excited direct current dynamos commonly have a combination of

series and parallel (shunt) field windings which are directly supplied
power by the rotor through the commutator in a regenerative manner.
They are started and operated in a manner similar to modern portable
alternating current electric generators, which are not used with other
generators on an electric grid.

There is a weak residual magnetic field that persists in the metal frame
of the device when it is not operating, which has been imprinted onto the
metal by the field windings. The dynamo begins rotating while not
connected to an external load. The residual magnetic field induces a very

6
small electrical current into the rotor windings as they begin to rotate.
Without an external load attached, this small current is then fully
supplied to the field windings, which in combination with the residual
field, cause the rotor to produce more current. In this manner the self-
exciting dynamo builds up its internal magnetic fields until it reaches its
normal operating voltage. When it is able to produce sufficient current to
sustain both its internal fields and an external load, it is ready to be used.

A self-excited dynamo with insufficient residual magnetic field in the

metal frame will not be able to produce any current in the rotor,
regardless of what speed the rotor spins. This situation can also occur in
modern self-excited portable generators, and is resolved for both types
of generators in a similar manner, by applying a brief direct current
battery charge to the output terminals of the stopped generator. The
battery energizes the windings just enough to imprint the residual field,
to enable building up the current. This is referred to as flashing the field.

Both types of self-excited generator, which have been attached to a large

external load while it was stationary, will not be able to build up voltage
even if the residual field is present. The load acts as an energy sink and
continuously drains away the small rotor current produced by the
residual field, preventing magnetic field buildup in the field coil.

7
History

The Faraday disk was the first electric generator. The horseshoe-shaped

magnet (A) created a magnetic field through the disk (D). When the disk
was turned, this induced an electric current radially outward from the
center toward the rim. The current flowed out through the sliding spring
contact m (connected to B') through the external circuit, and back
through B to the center of the disk through the axle.

The operating principle of electromagnetic generators was discovered in

the years 1831–1832 by Michael Faraday. The principle, 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 disc rotating between the

8
poles of a horseshoe magnet. It produced a small DC voltage. This was
not a dynamo in the current sense, because it did not use a commutator.

This design was inefficient, due to self-cancelling counterflows

of current in regions of the disk 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 counterflow limited the
power output to the pickup wires, and induced waste heating of the
copper disc. Later homopolar generators would solve this problem by
using an array of magnets arranged around the disc perimeter to
maintain a steady field effect in one current-flow direction.

Another disadvantage was that 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 a coil. Wire windings can conveniently
produce any voltage desired by changing the number of turns, so they
have been a feature of all subsequent generator designs, requiring the
invention of the commutator to produce direct current.

9
The first dynamos

Hippolyte Pixii's dynamo. The commutator is located on the shaft below the spinning magnet.

The first dynamo based on Faraday's principles was built in 1832

by Hippolyte Pixii, a French instrument maker. It used a permanent
magnet which was rotated by a crank. The spinning magnet was
positioned so that its north and south poles passed by a piece of iron
wrapped with insulated wire.

Pixii found that the spinning magnet produced a pulse of current in the
wire each time a pole passed the coil. However, the north and south
poles of the magnet induced currents in opposite directions. To convert
the alternating current to DC, Pixii invented a commutator, a split metal
cylinder on the shaft, with two springy metal contacts that pressed
against it.

10
This early design had a problem: the electric current it produced
consisted of a series of "spikes" or pulses of current separated by none at
all, resulting in a low average power output. As with electric motors of
the period, the designers did not fully realize the seriously detrimental
effects of large air gaps in the magnetic circuit.

Antonio Pacinotti, an Italian physics professor, solved this problem

around 1860 by replacing the spinning two-pole axial coil with a multi-
pole toroidal one, which he created by wrapping an iron ring with a
continuous winding, connected to the commutator at many equally
spaced points around the ring; the commutator being divided into many
segments. This meant that some part of the coil was continually passing
by the magnets, smoothing out the current.

The Woolrich Electrical Generator of 1844, now in Thinktank,

Birmingham Science Museum, is the earliest electrical generator used in
an industrial process. It was used by the firm of Elkingtons for
commercial electroplating.
11
 The Woolrich Electrical Generator in Thinktank, Birmingham

Dynamo self excitation

Independently of Faraday, the Hungarian Anyos 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.[11][12] It was also the discovery of the
principle of dynamo self-excitation,[13] which replaced permanent
magnet designs.
12
Practical designs

This large belt-driven high-current dynamo from around 1917 produced

310 amperes at 7 volts DC. The huge complicated commutator (left) was
needed to handle the large current. Dynamos are no longer used due to
the size and complexity of commutators needed for high power
applications.

The dynamo was the first electrical generator capable of delivering

power for industry. The modern dynamo, fit for use in industrial
applications, was invented independently by Sir Charles
Wheatstone, Werner von Siemens and Samuel Alfred Varley. Varley
took out a patent on 24 December 1866, while Siemens and Wheatstone
both announced their discoveries on 17 January 1867, the latter
delivering a paper on his discovery to the Royal Society.

13
The "dynamo-electric machine" employed self-powering
electromagnetic field coils rather than permanent magnets to create the
stator field. Wheatstone's design was similar to Siemens', with the
difference that in the Siemens design the stator electromagnets were in
series with the rotor, but in Wheatstone's design they were in
parallel. The use of electromagnets rather than permanent magnets
greatly increased the power output of a dynamo and enabled high power
generation for the first time. This invention led directly to the first major
industrial uses of electricity. For example, in the 1870s Siemens used
electromagnetic dynamos to power electric arc furnaces for the
production of metals and other materials.

The dynamo machine that was developed consisted of a stationary

structure, which provides the magnetic field, and a set of rotating
windings which turn within that field. On larger machines the constant
magnetic field is provided by one or more electromagnets, which are
usually called field coils.

14
 Small Gramme dynamo, around 1878.

Zénobe Gramme reinvented Pacinotti's design in 1871 when designing

the first commercial power plants operated in Paris. An advantage of
Gramme's design was a better path for the magnetic flux, by filling the
space occupied by the magnetic field with heavy iron cores and
minimizing the air gaps between the stationary and rotating parts.
The Gramme dynamo was one of the first machines to generate
commercial quantities of power for industry.  Further improvements
were made on the Gramme ring, but the basic concept of a spinning
endless loop of wire remains at the heart of all modern dynamos.

Charles F. Brush assembled his first dynamo in the summer of 1876

using a horse-drawn treadmill to power it. Brush's design modified
the Gramme dynamo by shaping the ring armature like a disc rather than
a cylinder shape. The field electromagnets were also positioned on the
sides of the armature disc rather than around the circumference.[18][19]
15
Rotary converters

After dynamos and motors were found to allow easy conversion back
and forth between mechanical or electrical power, they were combined
in devices called rotary converters, rotating machines whose purpose
was not to provide mechanical power to loads but to convert one type of
electric current into another, for example DC into AC. They were multi-
field single-rotor devices with two or more sets of rotating contacts
(either commutators or sliprings, as required), one to provide power to
one set of armature windings to turn the device, and one or more
attached to other windings to produce the output current.

The rotary converter can directly convert, internally, any type of electric
power into any other. This includes converting between direct current
(DC) and alternating current (AC), three phase and single phase power,
25 Hz AC and 60 Hz AC, or many different output voltages at the same
time. The size and mass of the rotor was made large so that the rotor
would act as a flywheel to help smooth out any sudden surges or
dropouts in the applied power.

The technology of rotary converters was replaced in the early 20th

century by mercury-vapor rectifiers, which were smaller, did not
produce vibration and noise, and required less maintenance. The same
conversion tasks are now performed by solid state power semiconductor
devices.

16
Historical uses

Electric power generation

Dynamos, usually driven by steam engines, were widely used in power

stations to generate electricity for industrial and domestic purposes.
They have since been replaced by alternators.

Large industrial dynamos with series and parallel (shunt) windings can
be difficult to use together in a power plant, unless either the rotor or
field wiring or the mechanical drive systems are coupled together in
certain special combinations. It seems theoretically possible to run
dynamos in parallel to create induction and self sustaining system for
electrical power. 

Transport

Dynamos were used in motor vehicles to generate electricity for battery

charging. An early type was the third-brush dynamo. They have, again,
been replaced by alternators.

17
Media appearances

Frayne has appeared and performed on multiple TV shows, including Friday Night

with Jonathan Ross, Snoop Dogg's Fatherhood, the MTV EMAs and more. He has

also featured in advertisements for the likes of Adidas, Samsung and Pepsi, and has

appeared on the catwalk for Naomi Campbell's Fashion for Relief.

Frayne's media appearances have regularly involved magic stunts with celebrities.

In May 2009, Dynamo levitated comedian Matt Lucas four feet off the ground in

front of a crowd at the Emirates Stadium in London.

Frayne collaborated with Pepsi Max in 2013, where he levitated next to a London

Bus driving through Central London. The stunt attracted media coverage from

across the globe, including Good Morning America and Sky News. Later in the

year, Frayne worked with Mercedes-Benz to create a video called Dynamo vs

Coulthard, featuring Formula One driver David Coulthard. In 2014, Frayne

worked with Hunter and became an integral part of their London Fashion Week

show. Frayne appeared to levitate and then made models, including Suki

Waterhouse, vanish in front of the crowd which included Stella

McCartney and Anna Wintour.

2015 saw Frayne work with Fiat to launch the Fiat 500X. Frayne made the car

appear in a beam of light in front of a live audience at the Copper Box Arena in

18
London for the car's pre-launch event. The live performance was a result of three

years of work and preparation by Dynamo. In March 2017, Dynamo worked

with Betfair to help the FC Barcelona team bond with a series of unconventional

training techniques. Dynamo first appeared at the club's training ground, before

working on visualisation exercises with the likes of Luis Suárez, Jordi

Alba, Gerard Piqué, Sergio Busquets and Sergi Roberto. Frayne has made multiple

charitable media appearances for Comic Relief, Sport Relief and Children in Need.

In 2010, he appeared on BBC One's coverage of Sport Relief, where he appeared

to turn lottery tickets into cash in front of singer Robbie Williams and

presenter Davina McCall. He then later performed a levitation in front of

comedian James Corden and a live studio audience.

Dynamo has appeared on networks and shows including ESPN, the BBC's Never

Mind the Buzzcocks and Young Apprentice and more. In 2013, Frayne was flown

out to Hollywood to film with pop band One Direction, as part of 1D Day. He also

opened the semi-final of Strictly Come Dancing with a magic and dance routine.

In February 2018, Dynamo appeared in an episode of Amazon Prime’s The Grand

Tour,[61] and in November of the same year, he made an appearance for Prince

Charles' 70th birthday, where he performed on ITV's We Are Most Amused and

Amazed.

19
Live tours

In 2014, Frayne announced his first live tour, Seeing Is Believing.[64] Frayne's

ambitions for the show were high, commenting to the press that “[he was] hoping

that like [he] did for magic on TV, [he could] reinvent the live magic show and

produce something fans have never seen before.”

Dynamo was initially booked to play a 10-date run of shows in the UK, [64] but

following high demand for tickets, the run was extended to three years and 145

dates, where he sold over 750,000 tickets and filled arenas across the UK,

Australia, South Africa and New Zealand.

As part of the tour, Dynamo became the first magician to headline The O2,

London. He performed at the London venue three times, with the final show being

screened live on TV.

Books

Frayne has written several literary accounts which revolve around his upbringing,

his personal story, magic and his relationship with the artform. In 2013, Frayne

released his debut book Nothing Is Impossible: My Story, which became a Sunday

Times Bestseller and was described as “a terrific read” by TV personality Jonathan

Ross.

20
In 2017, Frayne released Dynamo: The Book of Secrets, a fully illustrated

beginner's guide to modern magic with tips, tricks and some of his best kept secrets

for new, aspiring magicians to learn. The Book of Secrets reached number 1

position in The Guardian's Paperback Non-Fiction chart.

Charity

Frayne has worked with several charities throughout his career as a magician. As

well as his work with the BBC's Children in Need, Comic Relief and Sport Relief,

where he has appeared on screen performing magic. In 2016 Dynamo worked on a

film for Theirworld titled Safe Schools: Children can no longer wait, Directed

by Sebastian Thiel. In 2017 he was announced as Theirworld ambassador.  Since

then, Frayne has worked with the organisation to help promote the education

of Syrian refugee children. As part of his work with the charity, Frayne has

travelled around the world and to the United Nations to meet world leaders and

discuss opportunities to help Syrian refugees.

Personal life

Frayne was born in Bradford, England, to an English mother and a father of

Pakistani Pathan ancestry. Frayne is the eldest of four children, and his father was

in prison for most of his childhood, where he grew up on the Delph Hill estate in

Wyke, one of the most deprived areas in the UK at the time. Frayne suffered from

21
bullying at school, and as a result, his grandfather taught him his first magic trick

to make it seem like he was much heavier than he was in reality, so that other

children couldn't pick him up.

Frayne was diagnosed with Crohn's disease when he was a teenager, and had half

of his stomach removed when he was 17 years old. In 2018, he posted a video to

Twitter discussing his struggles with the disease following a bout of food

poisoning, which led to him suffering from severe arthritis, weight gain and rashes.

In 2012, Frayne married his partner, whom he met at a music festival. The couple

now live in Hampstead, London.

Honours and recognition

Dynamo was promoted to Associate of the Magic Circle for Performance by the

magicians’ society The Magic Circle in 2012, the same year that Dynamo:

Magician Impossible won the award for Best Entertainment Programme at the

Broadcast Awards. The show also won Show of the Year at the Virgin Media

Awards and received nominations for Best Entertainment Programme at

the BAFTA TV Awards and the 17th National Television Awards.

Frayne was awarded an honorary degree from Bradford University in 2013, for his

commitment to Bradford, improving opportunities for young people and his charity

22
work. 2013 also saw Frayne receive the Grolla d’Oro award at the Masters of

Magic Convention in Turin.

In 2015, Dynamo was named AMA Magician of the Year award at The Academy

of Magical Arts 48th Annual Awards Show. He was also given a Fellowship to the

Academy by its Board of Trustees. Dynamo was also awarded The Magic Circle's

Maskelyne Award in 2016, which is awarded for services to British magic.

Following series 2 of Dynamo: Magician Impossible, the show again won the

Broadcast Award for Best Entertainment Programme in 2013. Dynamo also won

the accolade of TV Show of the Year at the Virgin Media Awards and was

nominated for Best Entertainment Programme at the BAFTA TV Awards in the

same year.

In 2014, Dynamo: Magician Impossible was nominated for Best Entertainment

Programme at the both the BAFTA TV Awards and the Televisual Bulldog

Awards.

Dynamo was included in Forbes' list of The World's Highest-Paid Magicians in

both 2016 and 2017.

23
Conclusion

The original "dynamo principle" of Werner von Siemens referred only to

the direct current generators which use exclusively the self-

excitation (self-induction) principle to generate DC power. The earlier

DC generators which used permanent magnets were not considered

"dynamo electric machines". The invention of the dynamo principle

(self-induction) was a huge technological leap over the old traditional

permanent magnet based DC generators. The discovery of the dynamo

principle made industrial scale electric power generation technically and

economically feasible. After the invention of the alternator and

that alternating current can be used as a power supply, the

word dynamo became associated exclusively with the commutated direct

current electric generator, while an AC electrical generator using

either slip rings or rotor magnets would become known as an alternator.

24
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 a b Wightman, Catriona (3 February 2012). "Broadcast Awards 2012:

Winners in full". Digital Spy. Retrieved 16 April 2019.

 Christian (31 January 2013). "Broadcast Awards 2013 winners list". Digital

Spy. Retrieved 16 April 2019.

 "Dynamo Magician Live UK Tour Dates". BIG Live Acts. Retrieved 16

April 2019.

 "Magician Dynamo to bring Seeing is Believing tour to New Zealand". 11

April 2018. ISSN 1170-0777. Retrieved 16 April 2019.

 "Dynamo Magician Live UK Tour Dates". BIG Live Acts. Retrieved 16

April 2019.

 "StackPath". www.frontiertouring.com. Retrieved 16 April 2019.

 "Dynamo to bring Seeing is Believing tour to South Africa".

www.bizcommunity.com. Retrieved 16 April 2019.

 "Dynamo: Magician Impossible: It's all about sharing the wonder". ISSN

1170-0777. Retrieved 16 April 2019.

25