"Megometer" DC Voltmeter and Insulation Tester

 

serial number 1037

 

"Megometer" This is a combined DC Voltmeter and Insulation Tester housed in a wooden case. Dating from the 1930's or possibly even earlier, the meter and generator are housed in a wooden dovetail joint box, with a hinged protective lid which opens to reveal the meter.faulty

  

Connection panel and instruction labels (the two screws appear to move the generator up and down within the horshoe magnet to adjust the generated voltage)

  

These two views show the generator and the voltmeter series resistors (wound on porcelain formers).

The generator produced 450 volts as measured by an AVO but fell to zero when any load was applied. The meter was completely unserviceable and both wire wound resistors were open circuit.The meter was replaced with a !mA movement and the generator rotor shown below was removed and it was found that the soldered connection to the end of the winding had corroded and was making a poor connection. The wire is very fine and randomly wound and impregnated with varnish so it was difficult to locate the end. I made a soldered connection to two or three adjacent turns on the outside layer and reassembled the generator. It worked well but only produced just in excess of 300 volts.


Rotor with new connections.

 

For hand driven generators, Meggers and other insulation testers click here