Specifications

CONSTRUCTION
VR3 and VR4. But the mid-
range frequency compo-
nents get attenuated due
to capacitor C41 (0.047µF).
In the hi-fi mode (Q1
output of IC7 high), pole-P
of the switch is in contact
with terminal 1. In this po-
sition, normal gain is
achieved for entire audio
frequency range (since ca-
pacitor C41 is disconnected
from the feedback path).
When pole-P of switch
SW is in position 2 (Q2 out-
put of IC7 high), the at-
tenuation of mid-range fre-
quency components is re-
established and also the
gain of the amplifier for
very low frequencies in-
creases (since an additional
feedback resistance of 100k
(R25) is introduced in the
feedback loop). This is the
low-frequency boost mode.
When pole-P is in con-
R25,R32,R29,
R34 R41,R42 - 2.2-kilo-ohm
R43,R44 - 1-ohm
R45-R50 - 33-kilo-ohm
R61 - 680-ohm
R62 - 330-ohm,0.5W
VR1-VR3,VR6 - 47-kilo-ohm linear
potmeter
VR4,VR5 - 100-kilo-ohm linear
potmeter
VR7 - 220-kilo-ohm linear
potmeter
VR8,VR9 - 47-kilo-ohm log potmeter
Capacitors:
C1,C5,C17,C27-C30,
C32,C47,C59,C60- 0.1µF ceramic disc
C2,C4,C24 - 100µF, 25V electrolytic
C3,C11,C26 - 22nF ceramic disc
C6,C16,C22,C23
C34,C36,C22,
C23,C52,C53 - 1nF ceramic disc
C7,C15,C35,C37
C49,C50,C10,
C12,C51,C54 - 10µF, 25V electrolytic
C8,C13,C55,
C56,C57 - 47µF, 25V
C9,C14 - 15nF polyester
C18 - 100pF ceramic disc
C19 - 22pF ceramic disc
C20 - 10pF ceramic disc
C21 - 68pF ceramic disc
C25 - 1µF, 25V electrolytic
C31,C33,C46,C48- 2.2µF, 25V electrolytic
Semiconductors:
IC1 - LA3161 stereo preamplifier
IC2,IC3,IC5,IC6 - CD4066B quad bilateral
analogue switch
IC7,IC4 - HEF4017B decade counter
IC8 - LF353 JFET input dual
op-amp
IC9 - TA7230 stereo power
amplifier
IC10 - KA2281 stereo level
indicator
T1 - 2SC1815 npn transistor
T2 - CL100 npn transistor
T3 - BF494 npn transistor
D1,D12,D13,
D24 D25,D9 - 1N4001 rectifier diode
D2,D3,D4,D5 - Bilateral coloured LEDs
D6-D8,D14-D23 - Coloured LED
D10,D11 - 1N5408 rectifier diode
D26,D27 - 9.1V zener
Resistors (all ¼W, ±5% metal carbon film,
unless stated otherwise)
R1,R6,R10 - 100-ohm
R2,R7 - 7.5-kilo-ohm
R3,R8,R22,R23,
R28,R37,R39,R40- 100-kilo-ohm
R4,R9,R11,
R26,R35 - 10-kilo-ohm
R5 - 150-ohm
R12,R13 - 1.2-kilo-ohm
R14-R21,R51-R60- 1-kilo-ohm
R24,R27,R33,R30
R31,R36,R38 - 4.7-kilo-ohm
C38,C41,C43,C45- 0.047µF polyester
C39,C42 - 2.2nF polyester
C40,C44 - 6.2nF polyester
C58,C61 - 470µF, 25V electrolytic
C62 - 2200µF electrolytic
C63-C66 - 4.7µF, 25V electrolytic
C67,C69 - 1000µF, 25V electrolytic
C68,C70 - 4700µF, 25V electrolytic
VC1 - 8-25pF trimmer
Miscellaneous:
L1 - 5T, 22 SWG, 5mm dia air
core
L2 - 250T, 18 SWG over a
ferrite rod
X1 - 230V AC primary to 12-0-
12V, 2A sec. transformer
S1,S2 - Push-to-on tactile switch
- Tape drive mechanism
complete with 200-ohm
R/P stereo head, leaf
switch, and 12V DC, 2400
rpm motor
- Telescopic antenna
LS1,LS2 - 4-ohm, 8W, 9cm diameter
woofers with piezoelectric
tweeter
- Readymade FM/AM radio
reciever kit
- Cabinet
- Shielded cable
- Heat sink and other
hardware items
PARTS LIST
Fig. 6: Preamplifier, audio level indicator, and power supply (Section III)
32