Weighing nearly 24lbs (10.7Kg) it rests on two curved wooden supports at each end-these are rebated to prevent the coil from moving once in position. The hardwood oak base is free from woodworm and gouges and retains its original finish which obviously shows the age wear one would normally associate with over 100 years.This could easily be re-finished if a newer appearance is required. Overall dimensions of the base are 25 inches in length and 12 inches wide, with a total weight of 37 lbs (17Kg) including the coil. Inside the base are the ORIGINAL paper and mica primary spark suppression capacitor condensers. These have been tested and appear to have a nominal capacitance of approximately 1.5-2.0 uF.
Wire leads from these are connected to two of the end brass terminals-these are normally connected in parallel with the primary coil terminals, which are at the end of the primary core, as shown in the photographs. The main purpose of this condenser was to alleviate undue sparking at the primary interrupter contacts and increase the magnetic field rate of collapse, thereby improving the spark length from the secondary coil terminals. An unusual primary interrupter is utilised with this coil. Due to the very low resistance of the primary coil considerable current is drawn from the energising source, being usually in excess of 10-15 amperes at 12 volt. This particular coil was not fitted with the standard spring interrupter as the contacts would degrade rapidly with the the make and break operation, which causes high energy sparks at the contacts.
Instead a clever, manually operated sealed mercury (Hg) switch is mounted on a steel spring, coupled to a plastic lever. By simply using the lever to manually vibrate this spring the mercury in the sealed tube moves forwards and backwards over the contacts to rapidly energise and de-energise the primary coil.
The mercury stays intact and is capable of passing considerable DC current without the degradation that would occur with solid contacts, even rhodium or similar type. Due to the power requirements of this coil I have not tested it in a working state. The energy levels involved are highly dangerous and attempts to produce a working system should be done with great care! T his authentic coil would prove of great interest to the serious collector or museum.
The item "LARGE ANTIQUE INDUCTION/RUHMKORFF COIL-c. 1890's" is in sale since Thursday, January 31, 2019.This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "bown007" and is located in Middlesex. This item can be shipped worldwide.