The Cathode Ray Tube site
150 years of CRT evolution
The Dutch collection
150 years of CRT evolution
The Dutch collection
Ruhmkorff coils
Power source
Power source
Heinrich Daniel Ruhmkorff (1803-1877)
A German engineer working in Paris opened his own workshop in Paris in 1837 producing
scientific instruments. He gave his name to the high voltage coil around 1855 which was able
to generate tensions up to 200KV. It was a further development of earlier techniques.
The early instruments consist of a primary coil with a few thick high current windings and a
secondary coil with a high number of thin wire windings where the high voltage is formed by a
mechanical or mercury braker system. In the wooden base there is room for a capacitor made
of paper and metal foil. Ruhmkorff coils were used to activate the Crookes, Geissler and X-ray tubes.
Most of the coils come from the last quarter of the 19th and beginning of 20th Century, the
dimensions vary from small to huge ones, depending on the amount tension that was needed
which was expressed in centimeters.
A German engineer working in Paris opened his own workshop in Paris in 1837 producing
scientific instruments. He gave his name to the high voltage coil around 1855 which was able
to generate tensions up to 200KV. It was a further development of earlier techniques.
The early instruments consist of a primary coil with a few thick high current windings and a
secondary coil with a high number of thin wire windings where the high voltage is formed by a
mechanical or mercury braker system. In the wooden base there is room for a capacitor made
of paper and metal foil. Ruhmkorff coils were used to activate the Crookes, Geissler and X-ray tubes.
Most of the coils come from the last quarter of the 19th and beginning of 20th Century, the
dimensions vary from small to huge ones, depending on the amount tension that was needed
which was expressed in centimeters.
Heinrich Daniel Ruhmkorff
1803-1877
1803-1877
Early advertisement of Ruhmkorff coils and Geissler tubes.
This is a German Ruhmkorff small coil ca 1900. It measures 8x15cm.
French Radiguet Ruhmkorff coil
early 20th Century. 22x12cm
early 20th Century. 22x12cm
Close-up of the breaker system.
In the wooden bottom (box) of the old Ruhmkorff or spark
coil you will find a capacitor witch consists of paper
and metal foil. In one of my coils the paper sheets were
old book pages with photographs of pre WW I soldiers!
coil you will find a capacitor witch consists of paper
and metal foil. In one of my coils the paper sheets were
old book pages with photographs of pre WW I soldiers!
The early power source, the Grenet Cell
The Grenet Cell or pile invented by the German
Johann Christian Poggendorff (1796-1877)
It is a galvanic battery filled with an acid solution
potassium dichromate. The electrodes are made
of zinc and carbon and generates 1,96 Volts, in
practice many cells were coupled to make a
workable power source.
The voltage rapidly dropped when the cells were
used. The zinc element which is positioned in the
middle can be shifted upwards or lowered by the
middle connection on top.
Johann Christian Poggendorff (1796-1877)
It is a galvanic battery filled with an acid solution
potassium dichromate. The electrodes are made
of zinc and carbon and generates 1,96 Volts, in
practice many cells were coupled to make a
workable power source.
The voltage rapidly dropped when the cells were
used. The zinc element which is positioned in the
middle can be shifted upwards or lowered by the
middle connection on top.
Two small French Ruhmkorff coils early 20th century.
Sizes 15x9 and 7x12cm. These two coils are from the same manufacturer and were mainly used for activating small Geissler tubes and other physics experiments. Often sold as a complete kit including Geissler rotator for education.
Sizes 15x9 and 7x12cm. These two coils are from the same manufacturer and were mainly used for activating small Geissler tubes and other physics experiments. Often sold as a complete kit including Geissler rotator for education.
Traders
A Pericaud toy experiment box ca1920
Containing a Grenet cell with a bottle of potassium dichromate, Ruhmkorff coil, and a small Geissler tube.
Containing a Grenet cell with a bottle of potassium dichromate, Ruhmkorff coil, and a small Geissler tube.
A large Ruhmkorff coil ca1890
This coil measures 36cm coil length with a 63 x 30cm base plinth.It uses a mechnical breaker. Unsigned but most likely from the Ruhmkorff workshop.
This coil measures 36cm coil length with a 63 x 30cm base plinth.It uses a mechnical breaker. Unsigned but most likely from the Ruhmkorff workshop.
French Pericaud Ruhmkorrf coil
Pericaud from Paris made scientific toys like Ruhmkorff coils, rotators and Geissler tubes.
Pericaud from Paris made scientific toys like Ruhmkorff coils, rotators and Geissler tubes.
Collection of French toy instruments ca1900
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A small German coil made by Bing early 1900's
Max Kohl Ruhmkorff coil 1910-1930
This medium sized coil was produced by Max Kohl in many sizes and with different breaker systems from 1910-1930. In this case a 25cm coil length for about 12cm spark length with a mercury breaker. This is a coil in a rare mint and working condition.
This medium sized coil was produced by Max Kohl in many sizes and with different breaker systems from 1910-1930. In this case a 25cm coil length for about 12cm spark length with a mercury breaker. This is a coil in a rare mint and working condition.
Close-up of the mercury breaker system
Mercury or breakers were developed for X-ray use for a stronger spark. The larger x-ray coils were often used with separate mercury Foucault breakers or electromotor driven breakers.
Mercury or breakers were developed for X-ray use for a stronger spark. The larger x-ray coils were often used with separate mercury Foucault breakers or electromotor driven breakers.
Picture from the Max Kohl catalogue No50.
The Ruhmkorff coil is named after it's inventor Heinrich Daniel Ruhmkorff. It is basically a transformer with a breaker system which induces an EMF. A primary coil with a few thick copper windings surrounded by a secondary coil with many thin windings is capable to produce a very high voltage which was used in Physics research at schools and Universities.