On Sat, 31 Mar 2007 18:07:26 +0100, Eeyore
wrote:



John Larkin wrote:

Eeyore wrote:

Stunningly bizarre!

Do elaborate. I know the circuit very well actually. I've improved it hugely in
a series of amplifiers I designed also using the 'grounded collector'
arrangement.

Graham

Where to begin?

Is this amp supposed to be based on the patent you posted? It isn't.

The output stage is magnificently twisted, just to implement a silly
and inefficient transistor protection scheme. The same algorithm could
be implemented much more quantitatively with a few opamps and diodes,
off the side of the main signal path instead of all tangled with it.

Beta-dependent design sucks.

Way too many parts. Must be hell to work on.

Before-feedback output impedance must be insane, leading to
interesting dynamics.


I've seen this phenom elsewhere. Somebody gets an idea, falls in love
with it, and bends the entire design around it, usually badly.

I like to protect transistors by digitizing their voltages and
currents, and the heatsink temperature, running a realtime thermal
simulation, and limiting *junction temperature*.

John