December 1957 Popular Electronics
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
Point-to-point wiring of electronics
assemblies is rarely seen these days. For that matter, the use of leaded components is
rarely seen these days. The advent of printed circuit boards was a real breakthrough
concept when they became commercially viable in the 1950s. As the comic at the bottom
of the page suggests, many people did not even know what a printed circuit board was.
The air traffic control radar unit that I worked on in the USAF had all point-to-point
wiring in a trailer-full of chassis. Terminal strips and bus strips, bifurcated terminals,
tube socket terminals, and studs from relays and switches were the connection points
that the leaded components and wiring stretched between. Compared to a PCB (especially
multi-layered through-hole), servicing those assemblies was a piece of cake!
Printed Circuits Come of Age
By Allen Lytel
PRINTED circuits have come of age. Today they are an integral part of almost all electronic
equipment. Look at the nearest device: if it has been made in the past year, the chances
are that in it you will find printed circuits or components.
Some of the newest uses for printed circuits are in the instrument cluster connections
in an auto dashboard (see photo above). Guided missiles have compact, reliable controls
which use printed circuits, and so do midget tape recorders, jet planes, hearing aids,
electronic organs, and hundreds of other devices.
The most common type is an insulating board* with a pattern of conducting wires (below
right). A photo or printing process transfers the design to the copper-clad base and
an etching process removes the excess copper, leaving the circuit. In other methods,
the conductors are built up on the insulated base. Next step is the placement of components,
handled mechanically. In one machine all heads are controlled simultaneously, and as
the board is positioned, all the capacitors and resistors are inserted in one operation.
In another machine, they are inserted one at a time as the board moves down the line.
After the components are inserted, all parts are dipsoldered in place in a single operation.
Printed Circuit Board (PCB)
Figures 3, 4, and 5
The use of printed circuits has led to the development of modules. These are complete
circuits such as audio amplifiers, cathode followers or pulse generators.
Modules are built on a single board as a unit, acting as a standard circuit which
can be used in different end products. Figure 1 on the next page shows an experimental
TV receiver built of 17 modules which hold 153 of the 195 components (resistors, capacitors,
etc.) exclusive of the tuner. Other modular construction is of the type in Fig. 2. These
are plug-in boards as used in many computers and industrial controls. Tube and tubeless
types with diodes are shown.
These modules can be made up of smaller units. For example, several resistors and
capacitors can make up a package -- a "super component" -- and can be used on a printed-circuit
board (Fig. 3). In another way of treating the same situation, the components are encapsulated
in phenolic material (Fig. 4).
The newest development is flat Tape Cable (Fig. 5) which eases the task of interconnecting
printed wiring (see October issue of POPULAR ELECTRONICS, p. 72).
"Those the printed circuits you hear about?"
"If this works, you'll make hearing aid history -"
Posted July 10, 2011
These Technically-Themed Comics Appeared in Vintage Electronics Magazines: