ot coolest places

In a serious class C RF power amp, with amps of grid current, everything glows.

I think few radio or TV stations still use tubes.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Let's see if I understand you right. Mosfets are typically switches, so to control that sharp on/off region, you need some tight feedback loop to manage it as an amplifier? I'd never thought of that TBH!

Be that as it may, in the context of *this* thread, we are talking about ECC83s specifically. They typically run anode currents of around

Recommended reading: Radiotron Designers Handbook, it is the motherload of tube design info & much more "how to do it" stuff. It's pretty old, may have to dig around in Libraries to find a copy.

The heaters generally glow brighter than the cathodes but if the cathode isn't glowing at dull-red temperature, it won't emit properly.

From memory: Briggs's knowledge of valves (and circuits in general) seemed to be based on hearsay and rule of thumb. The book might be entertaining and handy for a dabbler but it wasn't a good reference source for someone who wanted to make reliable professional designs.

Terman's books are good:

The old RCA receiving tube and transmitting tube manuals were good.

Russell Varian's widow was not pleased with Terman.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Thanks, Liz! I just ordered it. Ed

It was entertaining for a 6 year old. Although I experimented with valves doing audio amplification (sometimes with a voltage doubler fed directly from 240V AC) I never needed to produce a serious design using valves myself.

How would one even notice a "dull-red temperature"?

It glows in the dark.

A glowing tube or two on a nice wood base might make a neat shelf ornament or night-light.

Use USB power!

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

MOSFETs tend to be used as switches, but if you are prepared to put them on decent-sized heat sinks and get rid of the heat generated in the devices you can definitely run them class-AB. If you used small bipolar transistors to control the MOSFET gate voltages in a sort of complementary Darlington configuration you could do pretty well.

Mosfets are not switches with some sharp on/off region. They have continuous transfer curves, like a tube or a bipolar transistor.

What I meant is that one can add an opamp to a mosfet and make the transfer curve arbitrarily linear and precise. That helps a lot when paralleling mosfets in linear applications.

SCRs and diacs and other 4-layer devices are inherently switches.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

And they are usually terribly crowded. Why do people want to feel like sardines in a can? To me the coolest places are right here where we live:

My MTB has panniers and I brought homebrew IPA plus Dixie cups so we hung out there for a while when I took that picture. The plop of a Grolsch bottle echoing back from the valleys is a heavenly sound :-)

We have the Pacific Crest Trail, from Mexico to Canada. It takes months to hike, carefully timed around the snowfalls.

Some locals are "trail angels" who help the hikers. We sometimes sit near the trail near Sugar Bowl, have a picnic, and if we see an especially weary hiker we yell "Do you want a beer?" Sometimes they are so shocked we have to repeat it.

I introduced one German guy to Chimay. He packed the empty bottle out.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Beautiful! Thanks for posting that. Ed