Radio Proximity Fuze Design

The sheer amount of stamp collecting required to assemble something like that staggers humanity. How one would avoid the temptation to get a more rewarding job such as selling advertising or endlessly painting the Verrazano Narrows Bridge, I have no idea.

Cheers

Phil Hobbs

Thanks, but only for trivia, anecdotes and useless drivel. I usually forget everything that's important.

Some more trivia. However, this came word of mouth from a potentially unreliable source. I believe it, but I'm not quite sure it's 100.0% accurate.

The first use of the VT proximity fuse was during the Battle of the Bulge in the Ardennes forest. The German attack was a total surprise to the allies, who were short on supplies, including artillery shells. Before the weather cleared and Gen Patton arrived, the US troops had almost run out of everything including artillery ammunition. What they needed were solid core anti-tank rounds and timed anti-personnel rounds. What they had was a mix of timed, contact, and VT fuzed anti-aircraft ammunition, possibly "borrowed" from the US Navy.

The surrounded US troops made do with what they had. The anti-aircraft ammunition sprayed hot shrapnel radially (horizontally), which was not quite ideal for anti-personnel air bursts, which work best by spraying shrapnel downward. Worse, shrapnel was useless against amored tanks.

See Fig 18, Pg 33 for the matching between that VT fuze antenna and shrapnel patterns.

Initially, the US artillery was firing contact fuze explosives. These were designed to explode as soon as they hit anything, which prevents burying the shell in the ground. They hit the tops of the trees (about 50 ft high), exploded, and sprayed shrapnel horizontally, with little effect. However, the psychological effect of having shrapnel slowly rain down from above, delayed by the leaves and branches, was probably considerable.

Then came the timed fuzes. These were adjusted by the artillery to explode at tree top level. That would have been just fine, except it was snowing and the spotters couldn't see the shell flight or point of impact though the snow and trees.

The VT fuzes probably worked at much less than their rated 50% reliability. They were made for detecting metal aircraft, not dirt or trees. With a metal airplane, the reflected signal is strong and predictable. From the trees, leaves, branches, and snow, the signal is absorbed rather than reflected. The VT fuzes would have worked reasonably well had there not been trees, snow, etc.

To prevent the Germans from finding the 50% of the "failed" VT fuzes, the VT fuze was designed to explode on contact (auxiliary detonating fuze) if the proximity electronics didn't detect a suitable target. Therefore, it worked exactly like a contact fuze and exploded when it hit the tree tops.

That begs the questions if the VT fuze did anything useful during the Battle of the Bulge. According to my potentially unreliable source, there weren't enough to make any difference and did nothing spectacular. My guess(tm), most did not trigger the proximity firing circuit.

This one is great. Like, literally. 951 pages.

I got it at some flea market, not for $58. The prox fuse circuits are cool.

Is the circuit description/ discussion any good?

George H.

No. There are an average of three schematics per page, each with a small descriptive paragraph.

I was thinking, once the electronics superstars were professors with suits and skinny ties and IEEE honors. A few years later, the heroes were genius alcoholics in shorts, and crabby guys throwing computers off roofs, and techs with no degree.

Whatever John Larkin does when he thinks he is thinking isn't up to much.

Edison and Tesla might be the first electronic super-stars, though they rather predate electronics as we know it.

Marconi would be the next, and Edwin Armstrong probably came next.

None of them were professors. Neither were my particular heroes - Allan Dower Blumlein, Bill Percival and Peter Baxandall - nor people like Bob Widlar and Barry Gilbert - though both of those did some teaching at the start of their careers.

Just bought a copy from abebooks.com for $9.51 with free shipping. It'll complement my 3 volumes by Graf and a few others.

Cheers

Phil Hobbs

Well, besides Widlar, Pease, and Williams, there were Dobkin, Gilbert, Engelhardt, and so on. (Not to mention our own late lamented Thompson.)

Besides, the skinny-tie guys were the ones that started the piranha-tank semiconductor culture of northern California. The semi business is nasty, and the semi equipment business is about as bruising as any I know of. (Walmart and GM are positively avuncular compared with Intel et al. You and I both have the marks to prove it.)

Cheers

Phil Hobbs

The SV culture is brutal. I assume that we will make them prototypes, show them how it's done, and then they will steal the design and do it themselves. They laugh at NDAs. They don't even return our test equipment.

The aerospace people in other places are great.

$9.51 won't even cover shipping. The beast must weigh four pounds.

Who is Graf?

Engelhardt, and so on.

Widlar was a star. Gilbert is almost as impressive, and Dobkin is a name I recognise. Pease and Williams wrote good application notes, but aren't in the same league. Mike Engelhardt, did a remarkably good job with LTSpice but that doesn't make him any kind of star.

The late, decidedly lamentable Jim Thompson was a further step down. Those of his circuits that I did use didn't make life easy for their users. Pease and Williams might not have been any more inspired, but they were more helpful.

Happily, I don't know anything about that. Analog Devices are a much nicer bunch - I even got to meet Barry Gilbert once.

snipped-for-privacy@gmail.com wrote: =========================

First realistic test was against RC drones in August 1942, fired from the USS Cleveland when novice gun crews destroyed 3 drones with just 4 shots.

The first military use was in the Pacific when the " USS Helena" shot down a Japanese dive bomber on January 5, 1943.

They were also used during the invasion of Italy in mid 1943.

The British used them from July 1944 onwards to effectively defend the UK from V1 "buzz bombs".

During the Battle of the Bulge ( began December 1944) some *200,000* VT fused shells were fired with devastating effect on German troops. General Patton," Blood and Guts", stated he was horrified by the slaughter.

Fun fact:

Actress Marilyn Monroe worked on the assembly of RC drones used by the US Navy.

..... Phil

I looked him up just now: Rudolf F. Graf. Turns out that he was an EE and ham (sounds like something from Doctor Seuss). He published _eight volumes_ of his Encyclopedia of Circuits, as well as a whole bunch of project books that seem to have been popular.

I have three volumes of the Encyclopedia, which are full of clippings from _Electronics_ (back when it used to be a real magazine), the trade press, and old repair manuals.

According to his obit in the NYT, he did 55 books in all. If the quality level is like the ones I have, the only possible explanation is OCD.

Cheers

Phil Hobbs

I ordered vol 2, $6.69 from Amazon.

Writing books sounds like hard work. 55 sounds worse. When Dorothy Sayers wrote her mysteries, she at least had a typewriter. Jane Austen had to use an ink pen.

An interesting book is Sayers "Murder Must Advertise", a Lord Peter mystery. The murder happens in an advertising agency, and there is a lot of detail about the physical processes involved in getting an ad into print. DS worked in advertising for a while and invented the Guinness toucan.

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y. It was a lifesaver in dealing with battlefield injury.

That's what I always heard from combat veterans of the conflict. Sulfadrugs were the miracle drug of the time. For the U.S. troops anyway, they were a ll fighting in a totally alien biological environment full of all kinds of pathogens to which they didn't have natural resistance. Even Europe falls in that category, they had to steer clear of untreated water, especially in France. Add an open wound to that equation and there's potentially serious trouble.

And the "Guinness is good for you" slogan, iirc. I think it was Lewis who said, "Dorothy wrote a book about advertising and the Bright Young Things, but was clearly far more interested in advertising." I'm a big fan of her Dante, as well.

Book-writing isn't that different from circuit design in some ways. Figuring stuff out and finding good ways to explain it are the fun part, like doing circuit architecture, coding something new, or testing first articles. (Or doing photon budgets. Designing stuff at a white board is in a class by itself.)

Checking the math, drawing the figures, looking up tabulated data, and updating outdated material is more like doing BOMs, kitting parts, and writing test procedures. And getting the whole thing put to bed involves a lot of fairly unpleasant grunt work not dissimilar to checking Gerbers and desk-checking the design.

And that's if you're basically writing what you already know. As Dr. Johnson said, "A man writing what he knows, flows pretty freely; otherwise he will turn over half a library to write a book." (From memory--the first half may be mildly wrong, but that's the gist.)

Still have to get that input capacitance problem nailed. I spent most of the week commuting to scenic Port Washington NY to do a clean-room code review for a court case. Object Pascal and C-Sharp, blech.

Cheers

Phil Hobbs

On Friday, 29 January 2021 at 21:48:51 UTC-8, snipped-for-privacy@highlandsniptechnology.com wrote: ...

.. I wouldn't paint all companies with the same brush. There exist large differences between individual company cultures, and even between different groups within companies.

I've worked in SV for forty years at multiple companies and rarely come across the behavior you frequently state.

At many places we would state up front that we don't accept NDAs because they are too onerous to guarantee that they are honoured and so not to give us information they would not want widely disseminated until we have a business agreement in place.

We did not want to be contaminated, even with the best intentions it is difficult not to get inspired by seeing other's creations.

The only company we had trouble with for returning equipment was Verizon (not a SV company) - we never got the unit back.

In about 30 years, the predator ratio looks like 100% to me. The place swarms with sleasy hucksters and bean-counter companies.

The culture turns "don't be evil" into "crush everyone even after you have so much money you don't know what to do with it."

And for free.

One problem is that the in-house engineers want to do it themselves so tell their management outrageous lies about ideas, completion dates, and actual costs. And they most always win.