spectrum utility - OpenLibra

SK1
•
connected. When you are
satisfied that all is well, plug
your Spectrum power supply into
the amplifier and plug the
amplifier's 2.1mm power plug
into your Spectrum 9 V power
socket. Plug in your computer
(and TV) and LOAD your
favourite arcade game.
Now connect the EAR lead
from your Spectrum to the
amplifier's 3.5mm jack socket
and start annoying the rest of
your family. . .
Fig. 3 shows the circuit
diagram of the BEEP Amplifier
and fig. 4 shows the copper foil
layout for the printed circuit
board. Table 1 lists all the parts
required for the project.
BUYLINES
All components used in this project,
with the exception of the
PCB, can be purchased from
electronics suppliers whoadvertise
regularly in electronics
Lo
RV1
PINS 3,4,5,10,11,12
ARE CONNECTED TO 0V
ARDWARE PROJEC'
+9V
CIRCUIT DIAGRAM rrm
magazines. The PCB is available
from Newtech (Micro)
Developments Ltd. of 1,
Courtlands Road, Newton
Abbot, Devon, for £2 .50 t 30p
postage. Newtech can also supply
a full kit of parts for £9.95
which includes a drilled case in
which to mount the amplifier,
PCB, loudspeaker, volume control
and all components (including
a knob for the volume
control).
Table 1, Parts List.
ICI LM380
C1 0.1uf Ceramic disc
capacitor
C2 4 7 Ouf Electrolytic
capacitor 16 V
VR1 22K LOG potentiometer
LS1 8R 2" Loudspeaker
SK1 3.5mm jack socket
SK2 2.1 mm power socket
PL1 2.1 mm power plug
Miscellaneous:
PCB, Case, 2 nuts and bolts for
SK 2, Knob, lightweighi
connecting wire, solder.
O
C2
BEEP AMP PCB
PCB COPPER FOIL PATTERN
2 : 1 SCALE
LS1 «
ZX COMPUTING APRIL/MAY 1985 113