In the days when having a valve "wireless" meant periodically purchasing an expensive High Tension battery of maybe 90 or 120 Volts and regularly taking your 2 Volt lead acid accumulator to the local radio shop or garage for recharging, it was necessary for the owner to have a means of establishing if the poor performance of the radio was due to "flat" battery or something more serious. These examples are typical of many which were available in the 1920's and 1930's. All these instruments are of the moving iron type.
Battery testing Pocket Meter chrome case with cardboard box DC 0-12V 0-120V working foreign
Battery testing Pocket Meter chrome case in imitation leatherette covered wooden box DC 0-12V 0-120V working foreign
Voltmeter Pocket DC 0-25V 0-250V not working
This little meter given to me by Brian Webster who inherited it from
his father. It doesn't work, the meter coil is open circuit (the larger
of the two in the picture below). I am puzzled as to why it has a red
mark at 18/180 volts and that it is labelled as “voltmeter pocket”
which makes it sound rather military though there is no broad arrow.
During the war his father was employed as an aircraft fitter in the
Midlands and his guess is that he used it when working on Spitfires.
Interior showing the shaped moving iron vane attached to the aluminium pointer. The larger coil provides the magnetic field and the smaller is a dropper resistance used on the higher voltage range. I believe that this is a later instrument probably dating from the 1940's as plastic sleeving on the interior connections was not commonly used until WW2.
Robert Holmes has kindly supplied the following interesting information about the firm.
Triangle Products was based in Manchester
at various locations. They were concerned with making equipment for the
motor vehicle industry (including battery testers and other
My interest is that my father-in-law worked for some years at Crypton-Triangle at Hyde near Manchester where they made heavy duty arc welders and rolling roads for vehicle testing. He worked on turning and grinding the rollers for these. The works closed down about thirty years ago but I believe manufacture moved to Somerset? He often told the story of how the boss of the firm used to test the rolling roads with his Jaguar- on one trial the car was so powerful it climbed off the rollers and shot across the works yard. After that they always chained the car to a fixed point during testing!