This is a teardown of a “Micronta” Digital Multimeter which was manufactured by Sinclair Radionics Ltd for Radio Shack (Tandy Corporation) in 1978. Sinclair launched the meter in 1977 and also supplied this meter directly under its own brand name with the model number PDM35 (derived from “Portable Digital Multimeter 3.5 digits). The Sinclair models had a white case whereas the Radio Shack model had a black case as shown here.
