April 1967 Popular Electronics
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1967 when this article article appeared in Popular Electronics, the
use of integrated circuits in consumer electronics was still relatively
new. RCA, GE, Westinghouse, and Philco had just released their first
TVs and radios with IC front ends, and Heathkit even had a build-it-yourself
model. The military was using them (ICs) in proximity fuse designs.
The new technology was really cooking. ESD issues were discovered and
needed to be dealt with as gate sizes shrunk and the vulnerability to
arcing became a problem. A photo is shown where NASA developed a method
for mitigating the potential damage by looping a spring-loaded wire
around the leads of MOS-based ICs during handling. A bit of nerd humor
is also presented to commemorate the April edition.
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By Lou Garner, Semiconductor Editor
A new manufacturing process at Eburn Industrial Research Corp. (Hingham,
Mass.) allows IC designers to pack 100 times as much circuitry into
the same area occupied by a conventional transistor.
The use of integrated circuits in consumer products is increasing at
an accelerated pace. Last year several major manufacturers started to
include IC devices in their TV sets (RCA) and table-model radio receivers
(GE and Philco). Heath followed suit shortly thereafter with a TV receiver
kit featuring an IC. H.H. Scott a major hi-fi equipment producer, is
now using IC's in the i.f. stages of its better line of FM receivers
and tuners. And the latest entrant in the field is Westinghouse Electric
Corp., with an IC portable phonograph. The new phonograph uses a conventional
record changer, but the familiar amplifier has been replaced by an IC
measuring only 0.112" x 0.085" and equivalent, performance-wise, to
39 components, consisting of transistors diodes, and resistors.
But the IC news is not limited to the domestic front. Two major
Japanese manufacturers, Sony Corp. and Matsushita Electronics Corp.,
are producing radio receivers using IC's, and another firm, Victor Co.
of Japan Ltd., is selling a 25-inch color TV set with a hybrid IC in
its sound channel.
The Military, too, is going for IC's in a
big way, not only in communications and computer applications but, more
recently, in the production of IC proximity fuses. A World War II development,
the proximity fuse is a miniature transceiver used in artillery shells
and bombs. In operation the device senses its approach to a target by
measuring the Doppler shift between shell and target. At a preset distance,
its detector circuit, activated by a reflected radio signal, detonates
the warhead charge.
Another recent development in the field
permits smaller firms to design custom IC's for their own products without
the high investment cost of a complete manufacturing facility. A sort
of "do-it-yourself" IC kit the new item is an open-cased monolithic
silicon chip measuring only 0.086" x 0.124" but containing 60 components.
The user interconnects the various elements as needed to assemble his
own custom circuit. Produced by Westinghouse Electric Corp., the IC
kit has been dubbed the "Insta-Circuit" and is available in both flat-pack
and TO-5 configurations. Suitable for manufacturers schools and laboratories,
the Insta-Circuit is definitely not a hobbyist item, since the special
microscope-equipped wire bonder required to make the final circuit connections
costs almost as much as a small car. The circuit chips themselves sell
for less than $40 each in unit quantities and less than $30 each in
quantities of 50 to 400.
Fig. 1. Two-transistor AM broadcast-band receiver circuit submitted
by reader Doug Zimmer features a Darlington pair amplifier (Q1 and
Q2), and a power switch that lets you select either a chemical battery,
B1, or a sun-powered battery (PC1).
Fig. 2. One of the many practical FET circuits described in a recent
folder from Siliconix, Inc., each stage of this phase shifter permits
continuous adjustment of phase shifts from 0°·to 180°.
Reader's Circuit. Agreed that simple AM broadcast-band receiver circuits
are literally "a dime a dozen," the circuit in Fig. 1, which was submitted
by reader Doug Zimmer (14332 35th N.E., Seattle, Wash.), combines a
number of interesting features that make it suitable for demonstration
or test purposes.
Doug has employed a standard tapped antenna
coil, with the tap serving as a means of matching the antenna. In addition,
he has used a Darlington pair amplifier (Q1 and Q2) and a dual d.c.
supply, permitting the selection of either a chemical battery (B1) or
a sun-powered battery (PC1) as the power source.
signals picked up by the antenna are selected by tuned circuit L1-C1
and detected by diode D1. Switch S1 provides optimum match for both
long and short antennas, insuring the best compromise between selectivity
and sensitivity. The detected audio signal is amplified by Q1 and Q2
and applied to an earphone plugged into output jack J1. Capacitor C2
serves to bypass the r.f. signal.
Switches S1 and S2 are
s.p.d.t. toggle, slide, or rotary types. Coil L1 is a tapped loopstick
antenna coil (Superex VLT-240 or similar) and C1 is a standard 365-pF
variable capacitor. A tubular paper capacitor or ceramic unit can be
used for C2; working voltage is not critical. Diode D1 is a general-purpose
type similar to a 1N34A and Q1 and Q2 are low-power pnp types (typically,
CK722, 2N107, or SK3003). An open-circuit phone jack is used for J1.
Either a penlight cell or standard flashlight cell will
be suitable for B1; PC1 is an International Rectifier type SIM silicon
solar cell. Doug recommends moderate impedance (500- to 5000-ohm) magnetic
earphones. And you can use either a printed circuit or point-to-point
wiring when building this receiver. Manufacturer's Circuit.
An interesting experimental phase shifter circuit is shown in Fig 2.
One of the 20-plus practical circuits described in a four-page folder
recently published by Siliconix, Inc. (1140 W. Evelyn Ave., Sunnyvale,
Calif.), the phase shifter permits a continuous adjustment of the relative
phase difference between its input and output signals. It can be used
for test purposes or to demonstrate the concept of phase shift. It is
particularly valuable for demonstrating the changes in standard Lissajous
figures as a signal's phase angle is varied.
Fig. 3. This is a simple device used by NASA to protect MOS transistors
from being accidentally damaged by the application of an electrostatic
potential across the leads while the transistor is being handled
or assembled in a circuit. A loop of flexible nickel wire is attached
to a music wire spring that is slipped over the transistor's case
and released, shorting together all of the leads.
The phase shifter consists of two cascaded split-load amplifier stages
with appropriate signal-combining phase-shifting networks between the
drain and source output points. Each stage provides from 0°·to 180°
phase shift. Resistor R1 serves as Q1's gate return resistor and as
the input load. Resistors R2 and R5 act as drain loads while R3 and
R6 serve as individual source loads. Combinations C1-R4 and C2-R7 form,
respectively, the first-and second-stage signal-combining network, with
the degree of phase shift determined by their adjustable resistive elements
(R4 and R7). Operating power is furnished by a 12-volt battery, B1,
controlled by s.p.s.t. switch S1.
Standard components are used
in the instrument. Transistors Q1 and Q2 are FET 2N2609's. All resistors
are half-watters; R4 and R7 are ganged potentiometers. Capacitors C1
and C2 are high-quality ceramic or plastic film types. Switch S1 can
be a toggle, slide, or rotary switch, as preferred. A variety of 12-volt
battery power packs can be used for B1 including two 6-volt portable
A types in series, or eight series-connected penlight or flashlight
cells. You can also power the phase shifter with a line-operated d.c.
power supply if you wish.
Observe good wiring practices when
assembling the device, and keep all signal leads short and direct. The
"Phase Shifter" can be wired on a suitable etched circuit board or on
a perforated phenolic board, and housed in a small metal utility box.
A sine-wave audio signal generator can be used as the prime signal source
for checking phase shifts.
OVERSIZE POWER TRANSISTOR
On April 1, the Lou Garner Enterprises announced the development
of the BMB transistor. Rated at a maximum free air dissipation of
about 10,000 watts, the new transistor is shown in the accompanying
photograph - note how the elements dwarf the nut and crescent wrench.
Beta values have not been calculated, but the alpha is reported
to be close to 1.0001 under typical operating conditions. Distribution
and quantity prices have not yet been firmly established for this
breakthrough.WITHDRAWN FROM MARKET
Due to production and patent problems, the Lou Garner Enterprises
on April 2 regretfully announced the withdrawal of the super-power
transistor. Interest in this new development was confined to April
Although possessing extremely - high input
impedance, insulated-gate field-effect transistors (IGT's, IGFET's,
MOST's, or MOSFET's) can be damaged quite easily by stray electrostatic
charges. To protect these devices against such damage during storage
and shipment, semiconductor manufacturers use techniques like wrapping
the transistors in foil, twisting or soldering the lead tips together,
or shorting the leads by means of a metal eyelet. However, none of these
techniques provides adequate protection when the transistor is prepared
for installation in a circuit since the leads must then be separated.
A recently published NASA "Tech Brief" describes a simple and
inexpensive device (Fig. 3) for preventing accidental damage when MOSFET's
are actually installed in a circuit. If you do work with these transistors,
you may want to use a similar device. It is made from short pieces of
0.033-inch diameter music wire and 0.007 -inch diameter nickel wire.
First, bend the music wire to form a spring with small end loops.
Then, form the nickel wire into a single loop and attach its outer ends
to the spring loops by twisting and soldering. The spring is compressed
during this operation so that the nickel wire is held under tension.
Squeeze the spring, expanding the nickel wire loop, and slip
the loop over the transistor leads until it touches the case. Then release
the spring, tightening the nickel wire loop and shorting the transistor
leads together. You can now remove the manufacturer's protection feature
(slip off the eyelet, untwist the leads, etc.). Finally, an insulated
Transpad is slipped over the transistor's leads and pushed up against
the taut wire loop to serve as a retaining disc.
transistor can now be inserted in its socket and mounted on a circuit
board, or soldered in position. Once the transistor is installed, the
protective device can be removed either by compressing the spring (opening
the nickel wire loop) or clipping the fine nickel wire. And another
thing: use a soldering iron - not a gun - when wiring MOSFET's, and
be sure to ground the tip of the iron to the substrate lead before soldering
the gate lead in place.
Until next month ...