Strobotac 631-A

• alternative name: GenRad

The General Radio Strobotac is a small portable stroboscope calibrated to read directly in revolutions per minute. Although designed primarily for speed measurement, it can also be used for the stroboscopic observation of rapidly -moving mechanisms. Illumination is furnished by a neon lamp mounted in a reflector which focuses the light at a distance of approximately eight inches from the instrument. The flashing speed is adjusted by means of an illuminated dial which is calibrated between 600 and 14,400 rpm. By using multiple synchronisms, speeds up to 72,000 rpm can be measured. Between 900 and 14,400 rpm, the accuracy of the scale is 2 ‰. The Strobotac operates from a 115-volt, 60-cycle, a-c line and provision is made for standardizing the scale in terms of the a-c line frequency. If desired, the flashing speed can be controlled by an external contactor or by the a-c line frequency.

For routine plant maintenance work and speed measurement, as well as for laboratory investigation on small areas, the Strobotac will be found entirely satisfactory. It is ideally suited for rapidly adjusting the speeds of a number of machines intended to operate at the same speed, as, for instance, textile spindles. Because of its small size and light weight, it can be used to observe the operation of mechanisms which cannot be reached by larger instruments. All controls are grouped on the right-hand side of the instrument and are easily accessible when the Strobotac is held in the left hand. The entire assembly weighs only 12 pounds.

Source: General Radio Co. - Catalog J (September 1936) - Page 3

Here you find 238 models, 212 with images and 128 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from General Radio Company; Cambridge (MA)