On Tue, 18 Oct 2011 19:52:01 +0200, petrus bitbyter wrote:

---snip--- (hint! :-) )

Makes me think of the old audio tube output amplifiers. The Miller
capacitor could make them yell like an HF-transmiter. Usually a stop
resistor in the grid circuit prevented this oscillation. So adding (or
increasing) the resistance in the gate circuit may solve the problem.

Some ancient neurons in my brain stirred. I think you mean Miller
capacitance? Not an external component but the effective capacitance at
the grid of a valve (or gate of a FET) due to the actual capacitance
between grid (gate) and anode within the device amplified by the voltage
gain of the circuit it forms.
http://en.wikipedia.org/wiki/Miller_effect

--
John Stumbles

I don't want to be part of a club that would have someone like me as a
member.