Fostex A-8 - Counter and Indicator Circuits

In this case, the "L" level from U9-19 is inverted to an "H* 1 level, applied to Q9
and Q10 to switch it on, thus feeding a base current to Q24 through R125 and D49
to switch it on, thus discharging C30.
Fig. 4-6
4.7 TAPE COUNTER DETECTING CIRCUIT AND MOTION SENSING CIRCUIT
Rotation of the left side reel table is detected by two photo-interrupters
and their outputs fed to the counter section. These outputs serve as the count
pulse and up/down signal.
The signals from the two photo-interrupters are converted, as shown in the
Signal Timing Chart of Fig. 4-7 and applied to the counter section as the count
pulse and up/down signal.
18