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Recording Equalizer Selector Circu it
The recording equalizer is switched to 4 separate
positions (METAL, CrOz, Fe-Cr, and STD). Tran-
Tapo solector
s r 3 0 r
E T A L
sistors Qror,Q+or, Qeos and Qeoz are tumed on
and off according to the position of the TAPE
switch Srlor, thereby switching the LC resonance
circuit in the recording equalizer, amplifier.
REC HEAD
^rrt t'X""'o"
R i l 5
c l t 9
I
o l o !
Fig.7-2 Tape selector circuit
7.3 LEVEL METER
The level meter circuit is shown in Fig. 7-3. It
consists basically of 3 ICs (ICaor, ICaoz and ICsor)
and 1 microcomputer.
Levels are displayed in
digitâl form using a fluorescent indicator tube.
1. The signal obtained from the output terminals of
the headphone amplifier is converted into a IC
voltage by means of a logarithmic compression
amplifier.
This DC voltage becomes the refer-
ence input for the comparator.
2. The comparative input to the comparator is a
DC voltage obtained by passing the indication
condition of the level meter through a digitaU
analog converter.
3. Accordingly, the comparator continually com-
pares the reference voltage with the indication
condition of the level meter, and sends signals
to the microcomputer so as to maintain the
comparative input (level meter indication condi-
tion) equal to the reference input.
The level meter is primarily a peak reading
meter, however it is possible to use it either as a
VU or PEAK HOLD meter by pressing switch
Ssor-r (VU) or Saor-z (PEAK HOLD).
7.4 ELECTRONIC COUNTER
The electronic counter consists of a micro-
computer (ICaoa) and a counter type fluorescent
indicator tube (Fig. ?-7). Sensing pulses emitted
from
the
mechanical assembly undergo rvave
shaping at Qaor to Qsosand then enter the micro-
computer (ICaoe ). The input pulses are added and
subtracted in the memory of the computer, and
the resultant numerical value is displayed at the
counter indicator tube.
XEAOPHONE
AMP
LEVEL
I|€lER
LOGARITHMIC
coMPRESSTOt{
AMP
s a o r - 2 : M E l É R
S€LECTOR
P . B . E O A M P
Fig. 7-3
Level meter circuit
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