Re: Baxendall Class-D oscillator with a big source inductor

On Fri, 26 Dec 2008 17:24:49 -0800, John Larkin wrote:
On Fri, 26 Dec 2008 12:22:15 -0800 (PST), MooseFET <kensmith@xxxxxxxxx>
On Dec 26, 10:58 am, "Bill Sloman" <bill.slo...@xxxxxxxx> wrote:
All the years that I've been fooling around with the Baxendall class-D
oscillator, I've believed the original paper, which said that if you
made the source inductor much bigger than the centre-tapped inductor in
the resonant tank, the circuit will "squeg", rather than settling down
to producing a nice steady sine wave. It certainly did when I wound
inductors that had something of the order of four or five times the
inductance of the inductor in the tank circuit.

I don't see any good reason for the topology you posted to want to squeg.
An increase in the center tap voltage biases the two MOSFETs on without
any delay. Are you sure you didn't leave out some detail of the circuit.

Squegging is usually caused by some bypassed biasing network that has a
slow time constant, as the bipolar version may have had. I can't find any
not-for-pay schematics of the original Baxandall oscillator.

Is this close?
http://home.planet.nl/~sloma000/Baxandall%20parallel-resonant%20Class-D%20oscillator1.htm
(mind the wrap)

It looks to me like an astable MV inductively coupled to the output.

Cheers!
Rich

.

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