The Cathode Ray Tube site  
150 years of  CRT evolution
The Dutch collection
Ruhmkorff coils
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 tension coil around 1855 which was able 
 to generate tensions up to 200KV. It was a further development of techniques used before.
 The instrument consist of a small primary coil and a large secondary coil where the high 
 tension is formed by a mechanical breaker system. In the wooden base there is room for an 
 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. 

 The coils are real often beauties with nice lacquered mahogany base and brass connections or 
 Heinrich Daniel Ruhmkorff
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
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!
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.
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.
Like it? Sign the Guestbook!
A Pericaud toy experiment box ca1920
Containing a Grenet cell with a bottle of potassium dichromate, Ruhmkorff coil, and a small Geissler tube.
A large Ruhmkorff coil ca1890
French Pericaud Ruhmkorrf coil
Pericaud from Paris made scientific toys like Ruhmkorff coils, rotators and Geissler tubes.
Collection of French toy instruments ca1900
A small German coil made by Bing early 1900's