Re: Frequency Halver

bill.sloman_at_ieee.org
Date: 03/19/05 

Date: 19 Mar 2005 15:05:45 -0800

Robert Baer wrote:
> bill.sloman@ieee.org wrote:
>
> > Sorry John, but I think you have just described a frequency
doubler,
> > rather than a frequency halver.
> >
> > For what it is worth, I'm pretty sure that there is no analog
technique
> > that will halve the frequency of a sine wave. It is easy enough to
use
> > a largely digital circuit to produce a sine wave which follows half
the
> > average frequency of of an analogue sine wave, and if you got
really
> > cute, you could track the phase of the input sine wave and produce
an
> > output whose phase varied at half the rate - though since the
maxima
> > and minima of a sine wave don't tell you much about the
instantaneous
> > phase, this isn't going to be perfect either.
> >
> > ---------
> > Bill Sloman, Nijmegen
> >
> Incorrect; over 40 years ago we did that at Sylvania with a
tetrode.
> See a previous response by me earlier in this thread.

You didn't halve the frequency of a sine wave, you used the input
frequency to excite a tuned circuit that was resonant at roughly half
the frequency of the input circuit, a much less direct relationship.

----------
Bill Sloman, Nijmegen

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