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Re: resonance tube



At 07:55 AM 9/16/2003 -0700, you wrote:
///
BTW a much less expensive method of detecting phase (than a PAR,
Stanford Research, etc.) is to use a center tapped secondary
transformer. In this case the primary is driven by the speaker,
unloaded (isolated) by a cathode follower (emitter follower for the
modern, op. amp. for the "really" modern). The output is compared to
the source (oscillator output) using another transformer, Its
secondary is in series with other's center tap and the center of a
balanced rectifier (the other legs of the rectifier go the the secondary
of the first transformer). The output of the rectifier is proportional
to the input signal and the polarity indicates the phase.
Unfortunately, unless the signal (and the reference) are constant, this
device does not give the phase angle, only whether it leads or lags the
reference. This device was invented for use with strain gauge bridges.

If your library hasn't discarded Hill's Electronics in Engineering,
(because it's so old, 1949) look on page 247 for the circuit and
description.

bc


Sounds rather like one of the several popular frequency (phase)
discriminator circuits formerly used in FM radios. Foster-Seeley
perhaps?


Brian Whatcott Altus OK Eureka!