Preset Station Selection; 2. Preset Tuning System - Akai AA-1010 Service Manual

2. PRESET TUNING SYSTEM
l) Preset Station Selecrion
For preset íatio. selection, there is a mechanical
and an eleclrical merhod. These are memory
equipme.t and seiection equipment enabling
desÍed station s€lection beforehand and selecting
thes€ pre-set srations by simply d€pressing the
respective switches.
An ordinary car redio, etc. utilizes a mechanical
station selection system wherein mechanical
variation is by mea.s of a variable condenser or
posilioning ofa dust corc inside a coil.
Model AA,1010L utilizes an electrical srálion
selection system and employs the varacror tuner
explained in a previous item.
2) An example of a stllion selection system employ"
ing a varactor tuner is shown in Fig. 6. For skrion
selection, push switches are used for s€lecuon
of voltage supply to the varactor tun€r. However,
in the AA.10I0L, these station selection push
switches are puÍe electronic system sensi.touch
3) Sensi-touch Employed Preset Station Selection
System Operation
The circult shown in Fig. 7 is th€ conlrol voltage
genêratinS pres€l volume and sensi-touch circuir.
Fig. 8 sho'rrs the inside of circuit sensi-touch IC
FPCI009C which include the 4 channel circuitry.
Terminals 14 thÍou8h 17 are the input teminals;
. e r m i n a l s @ , @ , @ , - a
@ a r ê t h e s t a t i o n
selection output terminals; and terminals O
,
@ , @ , and O are rhe pilot outpul terminals.
When channêl I sensor electrode is louched,
voltage is snpplied to the IC as rhe input signal
through fmger (body) resistance at t€rminal @ .
Then, the impedance is lowered at IC station
selector output terminal @ and current flows
ai shown by the arrow marks in Fig. 9. Consequ-
enlly, because the supply voltage 10 the varactor
runer diode is changed by the dividing ratio of
Rb and Rc, station selection is possible by
m€ans of setting the pr€set volumes beforehand
accoÍdrng to the deriÍed broadcarl tÍequen.res.