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.
I 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.
Here is a May 1967 Tips
for Technicians, a February 1969
Tips for Technicians,
and a May 1969 Tips for
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 problems.
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!
There's something 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.
DON'T FORGET TO ASK 'EM - "What else needs fixing?"
Posted March 4, 2012