This is only a preview of the November 1996 issue of Silicon Chip. You can view 23 of the 96 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Items relevant to "Build An 8-Channel Stereo Mixer; Pt.1":
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PRODUCT SHOWCASE
Hung Chang 20MHz
dual trace oscilloscope
trols are three pushbutton switches to
select Channel 1, Channel 2 or both
channels added together (ADD). By
pushing the INVERT button for channel 2, the ADD button will provide a
display which represents the difference between the two channel inputs.
This is not quite the same as having a
scope with differential inputs but it’s
a handy facility.
Above these controls and to the right
of the screen are the Power switch,
Intensity, Focus and Scale Illumination (for the screen graticule) controls.
Also in this section of the panel is a
screwdriver preset for trace rotation.
This can be used to ensure that the
traces are exactly parallel to the horizontal lines on the screen graticule.
As well, there is a Calibration terminal
providing a 0.5V peak-peak square
wave reference signal. This is used
for setting the compensation of the
scope probes (ie, for optimum square
wave display).
Timebase & triggering
This attractive oscilloscope has a 20MHz
bandwidth, dual trace operation and a
maximum vertical input sensitivity of 1mV/
div. Its timebase extends up to 0.1µs/div.
While many electronic hobbyists
might yearn for a 200MHz digital
storage oscilloscope with screen save
to disc capabili
ties, a great deal of
measurement work can be done with
a much lower priced instrument such
as this Model 6502 from Hung Chang
in Korea. It is quite compact, with
dimensions of 140mm high, 335mm
wide and 420mm deep.
The front panel manages to feature
all the usual controls while appearing to be very clean and uncluttered.
Even so, there are no less then 11
knob controls, 11 pushbuttons and
four 3-position toggle switches. The
active screen area is 10cm x 8cm and
the screen phosphor is blue.
To the right of the screen are the
vertical attenuators. These have nine
settings ranging from 5mV/cm to 5V/
cm in a 1:2:5 sequence. By pushing
the x5 MAG switch, the sensitivity can
be increased to a maximum of 1mV/
cm while knobs concentric with the
attenuator switches give continuous
variation of sensitivity.
To the right of each attenuator is a
3-position toggle switch allowing AC
or DC coupling and Gnd while above
each attenuator is the trace position
control for the respective channel. The
vertical input BNC sockets are beneath
the input attenuators with an earth
terminal between them.
Between the vertical position con-
At the far right of the panel is the
Time/Division switch giving 20 sweep
from 0.1µs/cm to 0.2s/cm in the usual
1:2:5 steps. Below this and to the left
are two 4-position toggle switches.
The first is for Trigger Mode allowing
selection of Auto, Norm, TV/V and
TV/H triggering, while the second
switch is trigger Source.
The positions provided here are
Internal, Ch2, Line and External. Note
that if the oscilloscope is being used in
the single channel mode, either Ch1 or
Ch2, then sync is provided by selecting
the Int source. To the right of these
switches is the Trigger Level control.
Above and to the right of the time
base switch is a timebase Variable
control and two pushbutton switches
for trigger slope (either + or -) and XY
mode. When pushed in this causes the
Ch1 and Ch2 inputs to be displayed as
an XY Lissajous plot.
Trace magnification
Two more pushbutton switches
provide timebase magnification (MAG
x5) and ALT-MAG.
November 1996 79
The first is self explanatory while
the second is not. When pushed it
displays an additional trace with
the timebase being five times normal
speed. If the scope is already in Dual
mode and ALT-MAG is depressed, then
four traces will be shown. This is quite
an unusual feature and can be handy
in a number of situations.
One control missing is that for selecting Alternate or Chopped mode
for dual trace operation. Instead, these
functions are selected automatically as
the Timebase speed is altered.
Trigger sensitivity for the Model
6502 on internal sync is quoted as
three divisions for DC to 20MHz bandwidth. Our sample easily exceeded
this spec. Reliable sync was obtained
up to 2MHz with a displayed signal of
less than one division and at 20MHz
with a two division signal. This is
good.
Another interesting point about
this scope is its very high maximum
sensitivity of 1mV/cm although this is
not useable in some situations where
the vertical input amplifiers become
unstable and oscillate. This is mentioned in the instruction manual and
can be cured by good grounding of the
KITS-R-US
RF Products
FMTX1 Kit $49
Single transistor 2.5 Watt Tx free
running 12v-24V DC. FM band
88-108MHz. 500mV RMS audio
sensitivity.
FMTX2A Kit $49
A digital stereo coder using discrete components. XTAL locked
subcarrier. Compatible with all
our transmitters.
FMTX2B Kit $49
3 stage XTAL locked 100MHz
FM band 30mW output. Aust
pre-emphasis. Quality specs.
Optional 50mW upgrade $5.
FMTX5 Kit $98
Both a FMTX2A & FMTX2B on 1
PCB. Pwt & audio routed.
FME500 Kit $499
Broadcast specs. PLL 0.5 to 1
watt output narrowcast TX kit.
Frequency set with Dip Switch.
220 Linear Amp Kit $499
2-15 watt output linear amp for
FM band 50mW input. Simple
design uses hybrid.
SG1 Kit $399
Broadcast quality FM stereo
coder. Uses op amps with selectable pre-emphasis.
Other linear amps and kits available for broadcasters.
80 Silicon Chip
signal source as well as placing a 220Ω
resistor in series with the scope probe.
Sweep linearity of the instrument
was good and the trace sweep times
within specification of ±3%. The displayed trace was very fine, with even
focus across the full screen area.
In short, the Hung Chang model
6502 oscilloscope is a good performer,
especially at its low price. Recommended retail price is $799 including
sales tax. Dual sensitivity 80MHz
probes are available for $39.95 each,
tax paid.
Our review instrument came from
Altronics, 174 Roe Street, Perth 6000.
Phone 1 800 999 007.
Price reduction on
Fluke graphical DMM
Fluke’s 860 series Graphical Multi
Meters have proved very popular
since their release in 1995. Combining
advanced multimeter capabilities with
waveform display, in-circuit component testing, trend plotting and logic
activity detection in one easy to use
handheld instrument, they represent
good value.
The Fluke 865, the mid-spec model
PO Box 314 Blackwood SA 5051
Ph 0414 323099 Fax 088 270 3175
AWA FM721 FM-TX board $19
Modify them as a 1 watt op
Narrowcast Tx. Lots of good RF
bits on PCB.
AWA FM721 FM-RX board $10
The complementary receiver
for the above Tx. Full circuits
provided for RX or TX. Xtals have
been disabled.
MAX Kit for PCs $169
Talk to the real world from a PC.
7 relays, ADC, DAC 8 TTL inputs
& stepper driver with sample
basic programs.
ETI 1623 kit for PCs $69
24 lines as inputs or outputs DSPTH-PCB and all parts. Easy to
build, low cost.
ETI DIGI-200 Watt Amp Kit $39
200W/2 125W/4 70W/8 from ±33
volt supply. 27,000 built since
1987. Easy to build.
ROLA Digital Audio Software
Call for full information about
our range of digital cart players
& multitrack recorders.
ALL POSTAGE $6.80 Per Order
FREE Steam Boat
For every order over $100
receive FREE a PUTT-PUTT steam
boat kit. Available separately for
$19.95, this is one of the greatest
educational toys ever sold.
in the family of three, is currently
being offered for a limited time at the
reduced price of $749.00 excluding
sales tax. The 865 features a basic
DC accuracy of .04%, selectable display modes, including Meter Mode,
Waveform Display, TrendGraph Mode,
In-Circuit Component and Logic Test
Mode. It is supplied with test leads
and battery eliminator and housed in
a shock-absorbing protective holster.
For more information, contact Obiat
Pty Ltd, 129 Queen St, Beaconsfield,
NSW 2014. Phone (02) 9698 4111; fax
(02) 9699 9170.
Mini-Circuits Designer’s Guide
To encourage
radio amateurs
to build and develop their own
communications
equipment, Mini-Circuits USA
are offering, free
of charge, their
RF/IF Designer’s
Guide. Mini-Circuits manufacture
an extensive range
of mini-modules,
such as RF amplifiers, freq uency
m ix er s, po wer
splitters, filters, detectors, attenuators, etc.
Circuits are available in various case style
packages to suit applications from surface mount
to external equipment mounts. Typical mixer
frequencies range from 10kHz to 4.3GHz, making
them ideal for LF to SHF work.
If you would like a free copy of RF/IF Designer’s
Guide, contact Mini-Circuits’ Australian representatives and stockists, Clarke & Severn Electronics,
PO Box 1, Hornsby, NSW 2077 or call (02) 9482
1944.
PCB POWER
TRANSFORMERS
Programmable
multimeters
Meter International has added
the MIC-3130 to the 3000 series of
programmable multimeters. These
allow the setting of low and high
levels of current, voltage or resistance. When a measurement falls
within the set values, a warning
tone is sounded. This can free an
operator from referring to the display when looking for a particular
measurement.
The Automatic Data Hold allows
the operator to concentrate on
probe placement, updating the display every three seconds on valid
inputs. A “beep” indicates the
reading is locked in. This feature
significantly reduces measurement
difficulty in confined areas and
increases safety when measuring
dangerous voltages.
A special feature of the MIC3130 is the option of connecting K
or J-type thermocouples, with the
display showing either °C or °F.
The MIC-3130 can also measure
capacitance from 1pF to 4µF over
four ranges. A frequency counter
to 4MHz is also included.
The unit comes in a rugged case
with pushbutton range selection.
The display has large 4000 count
1VA to 25VA
Manufactured in Australia
Harbuch Electronics Pty Ltd
9/40 Leighton Pl. HORNSBY 2077
Ph (02) 476-5854 Fx (02) 476-3231
digits with range annunciators.
A bargraph is incorporated into
the large 4000-count display. A
standard feature is the fast display
mode, which updates the display
every 50ms instead of the normal
300ms period.
For further information, contact
Computronics Corporation Ltd, 31
Kensington Street, East Perth, WA
6004. Phone (09) 221 2121; fax (09)
325 6686.
®
Design low frequency loudspeaker enclosures
fast and accurately with BassBox® software.
Uses both Thiele-Small and Electro-Mechanical
parameters with equal ease. Includes X. Over
2.03 passive crossover design program.
$299.00
RS-232 chips meet
ESD requirements
Analog Devices Inc has introduced
a family of +5V, RS-232 transceivers
which meets the European EMC
(Electromagnetic Compa
tibility) requirements. The ADM2xxE product
line is the industry’s first family of
robust, RS-232 and V.28 interface
tran
sceivers which provide ±15kV
of ESD (ElectroStatic Discharge) and
±2kV of EFT (electrical fast transient)
protection.
Designed for modems, printers,
laptop and notebook computers, the
devices offer low EMI (electromagnetic
interference) emissions in accordance
with EN55022 and provide compliance with the IEC-1000-4-x immunity
standards. These standards must be
met for all electrical or electronic
equipment carrying the “CE” (Comm
BassBox
Plus $6.00 postage.
Pay by cheque, Bankcard, Mastercard, Visacard.
EARTHQUAKE AUDIO
PH: (02) 9948 3771 FAX: (02) 9948 8040
PO BOX 226 BALGOWLAH NSW 2093
unaute Europeene) mark sold into the
European market after January 1, 1996.
Operating from a +5V supply,
all five devices come with latch-up
protection and immunity to high RF
(radio frequency) fields to allow for
operation in unshielded enclosures
and electrically-harsh environments.
The product line offers a variety of
driver/receiver combinations and all
devices are available in SOIC, SSOP
and TSSOP packaging
The ADM2xxE family offers a
pin-compatible upgrade for existing,
industry-standard +5V, RS-232 transceivers. Additional features include a
low power consumption of 17mW, a
guaranteed high data transmission rate
of 230 kbits/second, a 1µW shutdown
mode and operation over a temperature range of -40°C to +85°C.
For further information, contact
Hartec, 205A Middleborough Road,
Box Hill, Vic 3128. Phone 1 800 335
SC
623.
November 1996 81
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