P O W E R S U P P L Y S E C T I O N - JRC NDR-91 Instruction Manual

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and the line output when set to tÏNtrI.
The MHz knob is used for setting the l0 MHz and I MHz digits bf tne receiving
frequency. The MHz digit information is sent out in BCD code from this switch and this
output is set to l0 MHz and I MHz digits of the up/down counter. The lTÙNEl knob is
provided for setting the receiving frequency in 100 Hz steps. This knob is connected to the
circuit so called rotary encoder or pulse generator which generates 50 pulses for one full "
rotation. Pulse doubler circuit makes this 50 pulses double electrically, so that 100 pulses
are generated for one full turn. These pulses are connected to the 100 Hz digit of the
up/down counter. Therefore, for the f-ull turn of this knob, 100 (pulses) x 100 Hz, so that
full rotation can vary up to l0 kHz.
rumOWNl
switch is provided for fast forward for the receiving frequency. By setting
this switch to fq,
the up/down counter operates as the up counter. And the multivibrator
output is connected to the 100 Hz digit of the counter, thus the receiving frequency is
increased. By setting this switch to I DOWN l, the counter operates as the down counter and
the receiving frequency is decreased. The frequency increasing or decreasing speed by the
|ÙFDOWNI switch is set to appro x. 125 kHzlsecond.
The lLôôKl switch is provided for locking the set receiving frequency so as not to be
changed by careless misoperation. When this switch is set to ON (pushed condition), the
pulse output from the fTUtUelknob and multi-vibrator output generated by the IUPDOWNI
switch are prohibited to be applied to the counter. Therefore, the ITUNE I knob and
rumôWNl switch will not operate.
The FjMMEEI
knob is provided for controlling the brightness of LED by changing
the power voltage applied to LED on the front panel (frequency indicator, mode and
band width indicators).
5 . 4 P O W E R S U P P L Y S E C T I O N
The power supply section converts the external AC power or DC power to +17V, +l5V
and +5V DC required in each circuit and +5V for dimmer.
+l7V is used in the analogue circuit and +5V in the logic circuit. +15V is a special power
for audio power arnp (AF AMP.) IC. +5V for dimmer, which is controlled by the lDlMfvtEnl
knob on the fiont panel, changes within the range from approx. 0 to +5V.
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