Education/demonstration model - Composite - 1970-1980 - Polish galvanometer, 1974.

A rarely encountered, large universal demonstration galvanometer – an impressive instructional aid intended for a school or university physics laboratory. The device most likely originates from Poland and was made in the PRL period as a small-scale or workshop product, probably by a specialized workshop producing teaching equipment. It is well crafted, yet its unusual construction and the absence of a factory nameplate indicate it was not mass-produced. On the top element of the wooden frame, a paper label with the exact date “14-5-1974” has survived, allowing the item to be dated to the 1970s. The device is mounted on a solid wooden base and enclosed in a frame with transparent glass covers, enabling students to observe not only the swing of the large pointer but also the operation of the internal mechanism, coils, magnet, springs, electrical connections, and adjustment system. It is, in essence, an enlarged, exposed interior of a classic analog meter, designed so the principle of its operation could be observed by the whole class at the same time. When current is supplied to the movable coil placed in a magnetic field, a torque is produced that turns the coil together with the long pointer. Delicate springs oppose the motion, so the pointer stops at a point where the electromagnetic force is balanced by the spring force. The direction of deflection allows identification of the current’s polarity, while the magnitude of deflection corresponds to its intensity. The device was excellent for impressive demonstrations of electromagnetic induction – for example, while the magnet was inserted into and withdrawn from the coil, the pointer deflected in opposite directions, showing the change in the direction of induced current. The galvanometer could also serve as a balance indicator in Wheatstone bridge experiments. A suitable removable dial with a scale and a module containing a shunt or rheostat was inserted into the upper part of the device, allowing the same mechanism to be used as a galvanometer, ammeter, or voltmeter across different measuring ranges; with an appropriate rectifying arrangement, it was also possible to conduct alternating current demonstrations. The offered specimen does not include a removable dial with a scale, wires, or instructions – it is sold only as shown in the photos. The dimensions are 29 × 29 × 12.5 cm. The condition matches the photos, with natural signs of aging and former use: visible wear and scratches on the wood, dirt, local dulling of the transparent shields, and oxidation traces on metal components. The device has not been tested, as I do not have the necessary equipment or interchangeable measuring modules. I do not know if it works correctly, therefore it is offered as an untested item of unknown technical condition, primarily for collection, a technology museum, a historical physics laboratory, an exhibit, or possible professional restoration.

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