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October 1964 Radio-Electronics
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
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Zener diodes were first
introduced to the commercial marketplace in the early 1950s. They were named after
Clarence Zener, who discovered the Zener effect in 1934, which is the basis for
the operation of these diodes. As with many semiconductor components, Zeners were
still a relative newcomer to the electronics realm in 1964 when this full-page promo
appeared in Radio-Electronics magazine. The Mallory Type ZA molded-case
zener diode offered excellent voltage regulating characteristics at a practical
price point, making it suitable for service work, experimentation, and commercial
circuitry. With its comparable electrical properties and reliability record to military-grade
units, the Type ZA diode could be used for highly accurate power supply outputs,
as well as in clipper or damper circuits by biasing the diode negative. The lower
price of the Type ZA diode, which was about half that of hermetically sealed diodes,
made it an attractive option for a wide range of applications.
Mallory - Tips for Technicians: New Kind of Zener
Diode
 Typical shunt overvoltage protection
circuit using zener diodes. Output is controlled between V1 and V2.
 A zener diode, as you're probably aware,
is a special kind of semiconductor which has excellent voltage regulating characteristics.
It's the solid-state successor to the gas discharge tube. It acts like a rectifier
diode, blocking current in the reverse direction, until the "zener voltage" is reached
- then it starts to conduct with a capital C. The zener diode can carry appreciable
current continuously. So this makes it a fine regulating device. You can use it
in power supplies where you need highly accurate output. Or you can use it in clipper
or damper circuits, by biasing the diode negative.
The big news in zener diodes is that you can now get them from Mallory at a price
which makes them practical for service work, experimentation, or commercial circuitry.
The newsmaker is the new Mallory Type ZA molded-case diode. Its electrical properties
and reliability record are comparable to those of military grade units. In fact,
we use the same silicon cell in the ZA as in the zener diodes we make for military
requirements. But the price is only about half that of hermetically sealed diodes.
The ZA is rated 1 watt at 25°C. If you install it in a hot spot, you can
use it at ambients up to 100°C, derating linearly to 0.5 watt. Voltage ratings
go from 6.8 to 200 volts, in small increments so that you can get exactly the regulating
voltage you need. Standard tolerances are 20%, 10% and 5%.
You'll like the cold-case design of the ZA. No need for insulating sleeves when
you squeeze it into tight layouts. It's so small-only 3/8" long by 0.220" in diameter
- that it fits practically anywhere.
Your Mallory distributor has the Type ZA in a range of ratings. He also stocks
Mallory silicon rectifiers ... including handy packaged doubler, bridge and center-tap
circuits. See him soon!
Mallory Distributor Products Company
A division of P. R. Mallory & Co. Inc.
Indianapolis, Indiana 46206
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