April 1967 Popular
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.
April 1967 Popular Electronics
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By Lou Garner, Semiconductor Editor
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amplifier has been replaced by an IC measuring only 0.112" x 0.085"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.
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.
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
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.
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.
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.
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
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.
Radio-frequency 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.
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.
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.
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.
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.
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
Transitips. 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.
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 Fool's Day.
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
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.
The protected 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