John Larkin wrote:

Eeyore wrote:

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

It was Pat Quilter's trademark for ages. They've finally adopted emitter followers
now.

Horray! Give them another 20 years, and they may discover fets!

Personally I love the lateral 'audio fets' that Hitachi originated. Hitachi no longer
make them although there are some other suppliers. They are *very* expensive though
compared to bipolars..


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

Digitising ? That's not going to be cheap.

Digitizing is cheap, especially when it lets you safely get, say,
twice the usable power from a given mass of transistors and heatsinks.

You don't. Audio amps already push output devices pretty much as far as they're happy
with.

Here's a question for you.

Given a classic single channel of Class AB audio amplification with a rated output
power of say 600 watts, what kind of thermal resistance would you require to allow it
to continue to operate safely in typical use with an ambient air temp of up to 40C. Use
any sensible 'assumptions' that you feel are required to calculate this..

Graham