Optical display of magnetic tape feed - has Johnson code counter to cycle lamp display to give moving light effect indicative of speed and direction of tape

摘要

A moving display of four light emitting diodes is used to indicate direction and speed of the tape in a magnetic tape recorder. Operation of the selector keys (1) provides a specific mode for a ring counter circuit (4) controlling the state of four indicators (8). The ring counter is a Johnson type code unit that consists of four stages of J-K flip flop that are successively filled and then emptied of '1's. When the tape is fed forward at normal reading speed, a clock (7) cycles the Johnson code counter at 4Hz. This produces a display effect of lights moving rightwards. Other operating modes are indicated by different speeds and the opposite direction.