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TRC-70
CIRCUIT DESCRIPTION
«
Clarifier
controlled.
The data is controlled in the CPU so that the curve
C302
= R388
CPU
CLARFIERS 4
vrR200
>"
PLANO
A
VW
a ww @ ~"
Fig. 10-1 Clarifier circuit
*«
Encoder
When the encoder is turned, a pulse having a 90-
degree phase shift is input to the CPU. The EN1 pulse
is applied to PC3 of pin 20 and INT1 of pin 26.
The
CPU detects the trailing edge of the waveform via PC3
and the leading edge by INT1 and begins interrupt op-
eration.
It checks PC1 of pin 18, judges the rotational
direction, counts 1, then performs up/down process-
ing of the frequency and channel data.
Since the encoder is a mechanical device, it pro-
duces chattering, but it is designed not to malfunction
by software means.
20
PCS
EN!
INTL
10302
Encoder
18
CPU
>
-ENa
PC!
Fig. 11 Encoder circuit
shown in Figure 10-2 is obtained.
Operation of the
circuit is improved by enlarging the zero area at the
center of the rotation angle.
The zero point of the clarifier is adjusted by setting
the knob to the mechanical center, then setting zero
with VR303.
Fine adjustment frequency
4
+f
l
_i.
L
1
lL
—
Center
Rotation angle
>
Effective operation range
ii-
<@
pa
> atl
Physical rotation range
Fig. 10-2
*
Receive signal switching
13
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