Surge Current and Power in FETs

To be or not to be. That is illogical captain. We found the pointy ears hilarious. Just so you know.

It was a very old car at the time. It was my uncles's car and he complained to me some years later that I bled all over the seats.

I have a picture of my birthplace somewhere around here. It was close to midnight so my actual birthday is uncertain.

I have no idea. I still design electronics every day and he hasn't in decades.

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** Here is one ...

** JL definitely cannot see a joke, even when it is *right in front* of him .

...... Phil

He isn't. The car might have dated back to 1936 - and I only date back to late 1942 - but it seems to have stuck around for long enough to let Phil be born in it quite a few a few years later.

John Larkin doesn't design electronics. He just tweaks existing circuits until they work well enough in some new application for him to sell them.

I haven't been paid to design electronics since 2003. I've done it for fun since then, and have posted a few - fairly minimal - designs here from time to time. John Larkin hasn't found any of them remotely interesting, which is what you expect since he isn't interested in anything anybody else might have designed.

is probably the most recent design I've done. It's a reworking of a circuit I put together in 1986, but the detail is very different from what I'd put together then. Q3 (which as got nothing to do with the dual transistors Q3a and Q3b) is entirely new. My computer files for it date from August last year. I did post a link to it here when I first put it up "A current mirror variation on the Baxandall Class-D oscillator for producing a reasonable clean sine wave." on the 12th August 2020 and you posted a reaction to one of the other contributors to the thread on the 14th August, pointing out that the relatively trivial circuit he'd posted wasn't a Wien bridge, as he'd claimed.

Kevin Aylward at least commented on the cricuit, and claimed that there were simpler ways of doing job - since he thought that the circuit used six inductors (rather than six linked windings on one transformer) it isn't altogether surprising that he didn't come back with an example.

Amd yet elsewhere you write...

... and object when that is called bullshit!

a '38 Ford was my father's first car, he bought it in 1946 after coming home from the war. I believe he said he paid about $200 for it used with low miles which was almost exactly the discharge bonus a staff sergeant received at that time for two years of service.

Neither of my parents were born in a hospital, I was because I was born in the late 70s, at that time new mothers were kept in the hospital for observation for two or three days even after a regular birth with no complications which is unheard of today. Could probably smoke cigars in the maternity ward, too

That's what my uncle Wesley did, got discharged from the army and got married and bought an old car. Cars weren't manufactured here during the war, so that's what was available.

My uncle Sheldon was a radio operator in the war and opened a TV repair shop after and taught me electronics. Mo's dad had been a radio operator too, and worked for RCA after the war. I have his electronics class textbook with his meticulous notes. The war really bootstrapped electronics in the USA.

My dad was in the navy, in the pacific. I have his "Bluejackets Manual." He typed.

Sheldon had a big shed of surplus electronics, which, knowing Sheldon, he no doubt stole. I took anything I wanted. Heathkits were originally a lot of surplus parts.

100msec isn't getting you down the SOA much but maybe the rest can be calculated for worst case. Assuming lower possible wire resistance for the selected AWG, copper traces at max tolerance thickness, assume all connectors and switches at zero milli-ohms and the big capacitors at their max tolerance capacitance. That should give you peak current and time. [...]

Oh well my late father never stole from Americans he only "liberated" a few minor items from Italy. He would've liked to keep the two mother-of-pearl-inlaid Berettas he liberated from Europe for the return trip, too, they were sidearms for Mussolini's finest at one time. sadly Army customs frowned on that and confiscated them. Too bad, they'd probably be quite valuable today.

I got a Mullard vacuum tube in the mail the other day, a 6AL5 rectifier Didn't ask for any particular brand but it's a made-in-England with the military-grade CV140 designation. Probably from WW2 or Korean War era, maybe. Still new in its unopened packaging with the bakelite pin-protector on. Only $3! must have made a bajillion of these

Yes, yes, all that has been done, although none of the mins are actually known of course. I was talking to my 94 yo mechanical engineer friend yesterday about this and even he understands the issues of not designing close the edge. He worked for a pump manufacturer where he didn't bother with anything he couldn't put his head into the discharge tube. He worked at a nuke plant and was the guy to sign off on Bechtel's design who in theory designed it all. He has stories, good ones.

I have explained that. There are times to have multiple wild ideas and evaluate them. There are then times to solidify one design and implement it with engineering discipline and design reviews, to get it right the first time.

Not many people can do both. Most can't do either.

If you allow multiple people to make design changes on a PCB, you will sort it out after the boards are built.

Oh, I agree with all that. That's why I called "The best designs are necessarily accidental" bullshit.

The solution space is too big to explore systematically. Tweaks of existing circuits are not likely to be interesting or profitable.

So, how does one invent new circuits? I think it's like loosing a huge swarm of explorer bees in a tornado to spread all over the solution space and see what might be out there. It's like a qbit quantum computer that evaluates a huge number of possible states simultaneously, hoping that some useful pattern will collapse. I think brains work that way if you let them.

In my experience, the best designs have been found this way, by surprising accidents. I sometimes find things that I wasn't even looking for.

But you don't design electronics, do you?

Didi they mean "near complete failure?"

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** Got my kick start from a neighbor who was a tech working for Kodak in Melbourne - Ron Salter. His son Owen and I were playmates from the ages of 7 or 8. Ron was a Christian ( Methodist, later a Baptist ) so had some good values. When I was about 12, Ron started up a "radio club" for teenage boys and one girl from the neighborhood. So I became founding member - meeting every Sunday afternoon for a few hours in his home and garage. Theory and practical sessions were held.

Novices all built crystal ( Ge diode) radios first, then moved on to Ge transistors using "grounded base" topology . I was soon building tube amplifiers with AC power - so in the big time !

I got to meet my first 3 inch Philips scope there - heap powerful magic.

** So you are WAAAAY younger than me - I was born in 1952 - in a hospital.

Explains a lot.

...... Phil

A less mystical version is Pasteur's observation

"Chance favors the prepared mind."

but he didn't know about quantum mechanics.

Not exactly convincingly,

Nobody can do both at the same time. The wild ideas aren't wild by the time they get written into the specification. A great deal of perfectly adequate design is done by people who are merely perfectly adequate. When they start claiming that their particular ideas are "insanely good" life can get difficult.

Not if you sort it out right when the changes are being made. Design by conscensus can be a bit of a mess, but if you all know what you want the board to do, you can all apply your specialised expertise to the different bits of the board that need it, and make sure that the result works for all of you.

If you knew anything about quantum theory or quantum computers, this might have been worth saying. You don't and it wasn't.

By which you mean that Roger Penrose said something like that in "The Emperor's New Mind" (which I have read).

It's not a widely accepted hypothesis. Most people, seem to think that it is completely bonkers.

Which wouldn't have made any difference. You don't either.