JVC RC-550L User Manual

Technical Information
Hall IC (Integrated Circuit)
This recorder is adopted with the full automatic stop
mechanism. When the tape is finished in any mode: record,
playback, fast forward or rewind, the tape transporting
mechanism stops and the corresponding control buttons
return to their normal positions and the power is shut off.
The tape stop is detected by the Hall IC which is located in
the magnetic field of ring magnet: the magnet is connected
to the shaft of the tape counter and it is rotating while the
tape is running.
Ring
Magnet
Hall IC Fig. 1
HALL ELEMENT
The Hall IC consists of the Hall element and amplifier as
shown in Fig. 2.
The Hall element is one of magneto-electronic converter
and possesses the Hall effect.
Hail Element
Amplifier Output Stage
Fig. 2
5
>
The output voltage of IC is 3
proportional to the magnetic 3
field strength.
Flux Density B
Fig. 3
The Hall IC’ acts as an electronic switch which makes or
brakes a circuit according to the magnetic strength.
As the electronic switch does not have any contact, it
provides the longer serviceable life and the higher reliability
than mechanical switches e.g. reed switches.
HALL EFFECT
When a conductor or semi- =
conductor carrying a current F
is placed in a magnetic field
as shown in Fig. 4, the output
voltage is expressed by ,
H
Viz = Ry [le x B/t] Fig. 4
et
RC-550L/LB
where Ry is a parameter called the Hall coefficient,
Ic is the control current,
B is the magnetic field strength,
t is the thickness of the element.
CIRCUITRY OF TAPE STOP DETECTOR
Fig. 5
1. While the tape is running
1) The voltage wave mode as shown in Fig. 6 appears on
the output terminal of the Hall IC.
V V
4 "3
3 3
2 2
1 1
0 0
Fig. 6 Fig. 7
2) The wave (Fig. 6) is amplified by the transistor X105
and the bias voltage as shown in Fig. 7 is applied to the
X106.
The X106 becomes ON state, and the voltage across the
collector and emitter of X106 decreases to cut off the
X107.
3) The collector current of X107 does not flow so that the
solenoid does not function.
2. When the tape stops
1) The output of the IC maintains constant voltage (DC)
according to the magnetic field strength.
2) The DC voitage is choked by the capacitor C184.
3) The bias voltage does not change so that the X106
maintains the OFF state.
4) The voltage across the collector and emitter of X106
drives the X107 to become the ON state. and the
collector current flows.
The solenoid functions to stop the mechanism.
3. When the PAUSE switch is pressed
When the PAUSE switch is turned on, the bias voltage is
applied to the X106 and the X106 becomes the ON state.
The following responses are the same as ‘While the tape is
running’.
No. 1384

JVC RC-550L Specifications

General

Brand	JVC
Model	RC-550L
Category	Cassette Player
Language	English