In message <199610310003.SAA76207@audumla.students.wisc.edu>, Dave Mullenix wri
tes:
>The electronics magazines of the day had articles on these
>radios, giving the schematics.  There were even worse cases.  One
>electronics magazine found a "twelve transistor radio", but six of the
>transisters were confnigured as diodes and placed in series.  The authors
>couldn't figure out what in the world the designers intended the series
>string to do, but they replaced it with a resistor and the radio functioned
>just as well.

        They were spares in case one of the real ones bit the dust:-).

        Actually, this practice goes back farther than that.  Some
vacuum-tube radios had inflated tube counts with the extras being
ballast resistors.  In the cheapest radios of the day, there was no power
transformer and the cathode heaters of all the tubes were wired in series
such that AC mains voltage was across the entire string, but each tube heater
saw 6, 12, or whatever was supposed to be the correct filament voltage.
If the radio was a "deluxe!!!!!" model, the heater voltages didn't add up to
line voltage so the designers had dummy tubes which were just cathodes in a
glass container to take up the slack.  The more honest guys put a ballast
resistor which was usually flame-proof;
 (well they tried to make them flame-proof), to provide any missing drop.
 The clever honest guys made the AC power cord out of resistive wire
so that it was the ballast resistor.

        One last bit of trivia.  Old-timers referred to these xformerless
marvels as AC/DC radios because they would actually work if one ran them
off 110 or in other lands, 240 volts DC.  The rectifier was half-wave so
you might have to experiment with the plug polarity, but one orientation
would work.

        If some of you who are new to electronics ever run across one of
these sets, procede with absolute caution.  They were VERY dangerous with
the chassis being a floating ground and a 50% probability that mains voltage
might exist between it and Earth.

Martin McCormick WB5AGZ  Stillwater, OK 36.7N97.4W
OSU Center for Computing and Information Services Data Communications Group