Automatic location of blank section on magnetic tape - has level switching circuit which reacts to difference in amplifier output between blank and recorded tape

摘要

A search control circuit enables a section of recorded tape to be transported at high speed. When a blank section is located the speed is reduced to the normal recording speed. The output of the playback pick-up (1) is coupled to an amplifier (2) with a coupled search selection switch (3). A charge switching stage (4, 6, 31) is coupled to a charge-discharge stage (7, 9) operating into a Schmitt trigger (11, 12). An control stage (16, 17) allows the speed changing solenoid (18) to be activated. During search control operation, the amplifier output is processed to hold the output transistor (16) in the low state. When a blank tape section is encountered the trigger stage switches the output to activate the speed changing solenoid.