[Hallicrafters] vibrators

[Gerry Steffens]

There are two types of vibrators, synchronous and non-synchronous.  The
non-synchronous was the most common in auto radios, both 6 or 12 volt.
These didn't really make AC but rather mechanically chopped the input DC
voltage to make pulsing DC with a peak to peak of the pseudo-square wave
somewhere between 6.3 and approaching 8 volts or 12.6 to 14 volts.

The circuit that allows use of a standard filament transformer is that the
pulsating DC transforms like AC it's really a square wave with a center zero
to peak value of 1/2 the input voltage.  By applying the halves of the
chopped wave to opposing sections of the center tapped primary the effect
was a equivalent to 6 or 12 volts across the full primary winding. Many of
these transformers were around 25:1 ratio.  The common rectifiers used with
these were the 0Z4 or 6X5.

The other less common vibrator was a synchronous vibrator which had more
pins and also a second set of contacts to mechanically rectify the
transformed, now B+ level voltage, eliminating the  rectifier.

Sorry I don't have time now to further expand this hope it reads right.  I
must head to town to pick up my nephew.

Cheers from Minnesota,

Gerry

Gerald Steffens P.E.
Oronoco, MN

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