Icom IC-211 Instruction Manual page 40

IMHz DIGIT DISPLAY TRUTH TABLE
PHOTO-CHOPPER CIRCUIT
ОЗ and D4 are infrared LED diodes and О8 and О9 are the photo transistors. D3 sends
a continuous light source to О8 and D4 sends it to Q9. Between the diodes and the
transistors is a windowed chopper disk which is connected directly to the shaft of the
tuning knob. The diodes and photo transistors are set up so that a phase difference of
90 degrees results when the disk revolves.
The signals from Q8 and 09 аге fed to IC11 on the driver unit. Pin 11 of IC11 is con-
nected to the data input pin (Pin 9) of flip-flop IC9. The output from Pin 3 is divided,
and fed to Pins 8 and 9 of IC10. One is fed directly and the other is fed through a delay
circuit. 1010 is an exclusive OR gate IC, and both pulses of the positive edge and the
negative edge аге added to Pin 11 of 1С9 and О output is added to ІС9'5 reset terminal
through the delay circuit so IC9 operates as a monostable multivibrator. Q is fed to
Pin 1 of 1C10, the scan signal from the ACC socket (if used) is fed to Pin 2, and the
output signal is sent to the LSI in the PLL unit as the Clock (CK) signal. Pin 13 of IC9
is connected to Pin 3 and the delay circuits of RA9 and C6 are connected with the data
input Pin 5.
PHOTO-CHOPPER CIRCUIT SCHEMATIC DIAGRAM
SCAN
IC11 TENE ED |
ED: В
LOCK РА
UDC
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