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April 1966 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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There is no "e" missing
on the "Not-Worthy Circuits" title of this April 1966 Radio-Electronics
feature. Tak not of th month in which it appard (read that again). As with
other columns like "What's Your EQ?," these entries were submitted (maybe) by readers.
It could be a coincidence, but the last name of the designer of the first
circuit is V. "Dorftrottel," which is a German insult that roughly translates to
“village idiot” or "country bumpkin" in English. Entrant number two is Mr. Strom
"Kurzschluss," a family name which in German means "short circuit." I'm bginning
to smll a rat hr. It's up to you to decide whether, based on the foregoing
information, the third designer rounds out a trio of Fools.
Not-Worthy Circuits
Not to be built before April 1
 Voltage Dud-ler
A little-known low-current power supply circuit is based on the simple idea of
connecting the (or more) half-wave rectifiers in series.
It is well known, of course, that higher voltages than are available from a single
cell can be obtained by connecting cells in series, as in Fig. 1. It seems perfectly
practical to apply the same approach to rectifier supplies, and Fig. 2 shows a voltage
nondoubler designed accordingly.
- V. Dorftrottel
 All-Transistor Battery Discharger
This quickly built battery discharger will drain off any kind of battery, either
polarity, any voltage up to 12. It uses two 15-amp complementary power transistors,
connected as shown in the diagram. Resistor values are not critical. Both transistors
should be mounted on heat sinks (a common heat sink will do and the transistors
need not be insulated from it).
High-power transistors are somewhat expensive, but the convenience in being able
simply to connect any battery without observing polarity outweighed cost considerations
for this particular job. If you are willing to sacrifice that convenience, a single
p-n-p or n-p-n transistor will work equally well as long as the battery to be discharged
is connected with its negative side to the collector of the transistor.
- Strom Kurzschluss
 Accurate 60-Hz Drive for Synchronous Clock
Synchronous motors run at rated speed only when driven from a source of the correct
frequency. Clocks, for instance, will not keep time unless the line frequency is
exactly 60 Hz.
The circuit shows a simple oscillator-amplifier with enough 60-Hz sine-wave output
to drive an ordinary electric clock motor. Q1 and Q2 are a phase-shift oscillator,
with Q2 included to reduce the source impedance for the phase-shift network and
also to provide current drive for Q3, the output stage. The phase-shift oscillator's
normal free-running frequency is slightly above 60 Hz; a resistor from one side
of power transformer T2 feeds in enough 60-Hz line voltage to synchronize the oscillator
to the power line frequency.
T1 is an ordinary 6.3-volt filament transformer connected to step up the voltage
to just over 100. Total power output is approximately 3 watts. Capacitor C (paper)
resonates the transformer to 60 Hz for more efficient operation.
- C. E. Leakage.
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