May 1967 Electronics World
Wax nostalgic about and learn from the history of early electronics. See articles
Electronics World, published May 1959
- December 1971. All copyrights hereby acknowledged.
know I keep saying this, but it keeps being true so I say it
again: The basics of electricity and electronics have not changed
in the last 50 or more years, so there articles from vintage
issues of electronics magazines are as applicable today as they
were back then. If you are just getting into the field of electronics,
valuable information can be found here to supplement your learning
process. In fact, I have seen examples in some of these articles
where I re-learned something long-ago forgotten, and some of
the stuff is rarely, if ever, seen in contemporary writings.
Regardless, making yourself aware of the work done by pioneers
in the industry is always valuable because it gives you a sense
of approaches taken that have led to success, and sometimes
failure on the way to eventual success.
Tips for Technicians
Capacitor stability at bargain prices
Any capacitor changes its microfarad value when temperature
varies. And some capacitors change more than others. In some
circuits, capacitance drift with temperature can cause real
Look at circuits where you have fractional microfarad values
of paper, film, ceramic or mica capacitors. During warm-up from
room temperature to 65° C ambient, a capacitor with a temperature
coefficient of, for example, 500 parts per million per degree
C will increase capacitance value by 2%. This change is enough
to cause troublesome drift in tuned circuits, where inductance
also increases with temperature. It can knock the accuracy of
a timing circuit off, or mess up the performance of a differentiator
network. For these applications, we have a new kind of capacitor
that beats anything we've seen in the stability race. It's the
new Mallory Polystyrene Capacitor. They're made of stretched
polystyrene film and high purity aluminum foil. The assembly
is fused into one piece, with the polystyrene forming a solid
case of clear plastic that you can look through and see the
foil. Their temperature coefficient is less than 150 parts per
million per degree C, which is about half that of polyester
film capacitors. And the coefficient is negative; capacitance
goes down when temperature goes up, compensating for the upward
drift of inductance elements in tuned circuits.
Want more? Mallory Polystyrene Capacitors have the lowest
dielectric loss ... only a small fraction of that of other film
capacitors. Their insulation resistance is way above that of
mica, film or paper capacitors. And the best part of the whole
deal is that they're really low in price!
new from Mallory, too, in stable electrolytic capacitors. It's
the molded-case MTA, which has temperature stability that beats
most metal case types. It has shown up so well on life test
that manufacturers are using it in instruments and computers.
And while it's priced down with cardboard-case tubulars, it
beats them every way on quality.
You can get these stable
Mallory capacitors, and everything else you need for service
or experimenting, from your nearby Mallory Distributor. Ask
him for a copy of our 1967 General Catalog, or write to Mallory
Distributor Products Company, a division of P. R. Mallory &
Co. Inc., Indianapolis, Indiana 46206.
TO ASK 'EM - "What else needs fixing?"