Original Item: A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit. A voltmeter in a circuit diagram is represented by the letter V in a circle.

These were widely used by the Imperial Japanese Navy during WWII, as there were numerous electrical circuits and devices on ships that needed routine maintenance and repair. This example looks to possibly be civilian issue, then used for use in WWII. There are numerous kanji markings on the front and on the side of the wooden housing, which we unfortunately are unable to read.  It reads up to 300 Volts, and is marked TEW in a rectangle on the front. It has attachment points for leads on the top, however the knurled nuts are missing. It has a push button on the front that we assume takes a measurement. It measures approximately 7" x 7" 4", including the feet and top button.

Definitely a high quality item, ready to display, or possibly use!

Voltmeters are made in a wide range of styles. Instruments permanently mounted in a panel are used to monitor generators or other fixed apparatus. Portable instruments, usually equipped to also measure current and resistance in the form of a multimeter, are standard test instruments used in electrical and electronics work. Any measurement that can be converted to a voltage can be displayed on a meter that is suitably calibrated; for example, pressure, temperature, flow or level in a chemical process plant.

Most Navy technical manuals provide voltage charts that list correct voltages at all primary test points in a piece of equipment. Voltage measurements, when compared with these charts, provide a valuable aid in locating troubles quickly and easily. However, if the sensitivity of the test equipment differs from that of the test equipment used in preparing the chart, the voltage measurements may not reflect true circuit conditions. You must keep in mind that a voltmeter with low sensitivity used on a low range may disturb circuits under test or provide a false indication. Most technical manuals will tell you what type and model of test equipment was used to prepare the voltage charts. As a rule of thumb, the input impedance of the voltmeter should exceed the impedance of the circuit by a ratio of at least 10 to 1. Technicians have spent uncounted hours of wasted time because they have selected improper test equipment.

A voltage meter was a crucial piece of equipment aboard a Japanese ship or submarine during WWII. This example is in nearly in unissued condition. Naval Submarine gauges are not easily found, being much rarer then the Aircraft gauges.