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Community spirit? You are pretty much an insult machine. And most of your posts are off-topic.

John

He has posted several from his product line. Perhaps you would have seen them if you had not got him killfiled?

I've seen some company drawings. Can I certify John did them? No!

All his posted sketches have been JUNK. ...Jim Thompson

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If you want to talk about electronics, do it. If you want to sit in the cheap Senior Citizen seats and generate ritual lame insults, that's easier.

John

Can I certify you did any of yours? No!

You really think he puts his own name in the title blocks of (some of) his released company drawings just in case he needs to show off on SED?

Well I disagree. Of course the sketches are not fully worked out production-ready circuits - they are *sketches* to show an idea.

And when he *has* posted fully worked out production ready circuits you won't even accept that he did them!

Yes, many.

I've seen many of his designs in production, from 30 years ago and beyond.

-- Cheers, James Arthur

All the circuits that I've posted (except for the obvious photos of pages from books, like the proximity fuse stuff) were designed by me.

I used to design 100% of all my company products, and write the uP code, and sometimes lay out the boards. Lately, with things getting denser and more complex, we often have two or even three engineers work on a design, and a schematic can run to 30 pages or more. On the light source thing I'm doing now, I did the analog and picosecond and fiberoptics stuff, Rob did the switching power supply, Shannon is working on the PCI Express sheet, and somebody not-me will do the FPGA and uP code. Not many people can do it all any more.

I still like to do 100% of a product once in a while, like the little photonics boxes. I find that satisfying, especially the PC layout.

I'm used to brainstorming circuits with other people, several times a day. One of the guidelines for brainstorming is that any idea, no matter how goofy, can be a basis for discussion. People whose first reaction to a new idea is to criticize it, are the enemies of ideas.

I'm happy to post good/bad/half-baked/unfinished ideas to whiteboards or to newsgroups. If anybody can't or won't play the idea game, let them sit and grunt and cluck.

Jim won't post anything but home repairs. It's all "proprietary", or, as he claims, he's afraid I'll steal it, like in the case of his better-than-mine nanosecond linear ramp.

John

Sketches that don't work, period, tend to bias one's viewpoint :-) ...Jim Thompson

But he's senile now ;-) ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

He was legend in New Orleans after he left. Chief engineer at the premier local company. Lots of stories.

He designed a switcher back when no one cared about power and everyone used big iron, BIG heat sinks, 2n3055's, and fans.

It was alien technology at the time, like a ship from outer space. Everyone stared and wondered how it could possibly work. And yet it worked. Had '3055's for the switching element, IIRC (which I might not--it's been a while).

-- Cheers, James Arthur

The output transistor was indeed a 2N3055, driven by a PNP 2N2905. The

The weird thing was that it ran from 24 volts in, 5 out, and I couldn't buy a 24 volt schottky diode in those days. So I center-tapped the inductor and put the catch diode there. That worked, but it really increased the ripple current into the output cap, so I had to beef that up.

I didn't think it was very remarkable at the time. This was for the LHA ships control systems, where we had 24 volt battery backup.

John

You're welcome, but you should have that leak fixed! :)

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My Tek 7000-series mainframe(s) tapped their buck switcher's flyback inductor into a BJT for the catch-diode, a Cro-Magnon synchronous rectifier. Beautiful.

This precharger switcher of mine uses a current-controlled on-time and a voltage-controlled off-time. Straight PWM and constant off-time schemes don't give any time for inductor current to fall when the output voltage is close to the supply voltage, which means the switcher would have to produce impossibly short spikes. It can't, so inductor current rises out of control.

By tacking on a few parts enforcing off-time proportional to output voltage, I get a wide (10:1 ?)-ranging switching frequency producing a fairly constant ripple current over the whole range. That's pretty much optimal, as good as it gets.

It's down in the lab, begging to be played with...

-- Cheers, James Arthur

That's the great thing about electronics; you get to play for a living.

John

I guess that none of them had ever seen the HV circuit in a TV that not only used a simple 'switcher', but some used feedback from the HV to regulate it.

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Dunno. I came years later. The TV HV thing is a bit different, in that it's usually a blocking oscillator into a flyback, right?

The spin-off / competitor I joined was still using linear supplies when I started, regulating +28v down to +5v to run TTL.

-- Cheers, James Arthur

It produced the horizontal sweep and HV with one transformer. Some power the entire TV set. It's not a simple blocking oscillator, since the output has to be a linear ramp to get good H linearity sweep. The H sweep is synched to the video by recovering the Sync signal and separating it into H, V and Blanking outputs. They used a low impedance tap to drive the H sweep coils in the yoke. The wave shape was more critical in Color sets, since it also drove the convergence circuits. Some SS switchers were quite simple by comparison.

The earliest TVs simply had a free running oscillator driving a stepup transformer for the HV. The frequency and output voltage weren't controlled very well. They ran well above the H sweep frequency to prevent it from affecting the sweep signal.

I've never seen that, except something that used under 100 mA.

The really earliest TVs had a 60 Hz transformer and a vacuum diode rectifier to make the HV. As did the early oscilloscopes.

John