1A DC Interchangeable Dial for Demonstration Meter Metal Labware_Metal Bases & Rods this decade box selects cascaded

this decade box selects cascaded values for RC-time-constant

Double-concave glass lens at 3-inch diameter and 200mm diverging focal length

Aluminum-cased plotting compass with a glass face and a dial marked with principal points

Hand-cranked Van de Graaff generator with a 9

Plastic interchangeable dial with sealed shunt or multiplier housing

1A DC Interchangeable Dial for Demonstration Meter Metal Labware_Metal Bases & Rods this decade box selects cascadedOne amp AC scale on a 315x115mm laminated panel with sealed shunt, dropping into the demonstration meter as a 0 1A AC ammeter for transformer and household current measurements.