devices of unecessary complexity

Rightio!

See my message to Gunner, page 58/9 for maintenance and hazards. It'll be hard enough to stay clear of toxins after the Fall. I don't need to bring them into my life on purpose, y'know?

That's usually when the damned things die on you: before you get the money. "You're not going to sell _me_, you SOB!"

Hayull no! I buy more refined machinery, sir.

No, no, Gunner. He did NOT say he had a boatload of 35mm cannons. He's talking cameras. ;)

Personal computer operating systems

I now have a Fujji camera that uses my old F lenses and new modern electronic lenses from Nikon. And mine runs on AA cells. Martin

No, the daily/weekly/monthly cleaning, toxins, etc. It's a dirty and time-consuming procedure. BTDT. Pass, for now, thanks.

Hate 'em. My fireplace is boarded over for several reasons. First is that it's cracked, so flames might reach my attic. Second, I removed and sold the insert (which they torched the beautiful 1/4" steel plate heatilator to get it in the first place ). Third is that I hate the smoke fires create into the house, even in well built stoves and hearths. (Might as well be smoking again. No, thanks.) For all of you who will say "My stove doesn't let any smoke into the house.", I'll just file you with the folks who say "My dog doesn't bark." and "Gun control works."

Yes, it's a viable way to produce gas for a vehicle. It's just not one I wish to use for the time being. I reserve the right to change my tune (in a hurry, if necessary) soon after the Fall.

Hey, if you want dioxins and soot and nasty smell all over you, fine. I guess that's not too far beyond being a ciggy smoker.

[ ... ]

I've got one of the later Omega D-series enlargers, along with a B-series (both accept the same lens boards and film holders). The D-series has slots in the beam for three autofocus linear cams, and the B-series has two. And the D series has the Chromega head for color printing -- acquired just about the time I gave up on home darkroom work. :-)

There is where the Zeiss Contax -- or the early Nikon cameras, at least through the Nikon F -- win. Ever see a "Contax Cassette"? A double shell cassette, one shell rotating inside the other to close to form a light trap, or open to let the film pass out touching nothing, so none of the scratches which the old felt on used cassettes gave after a while.

Anyway -- the cameras listed could use *two* of those cassettes, feed and takeup -- (both opened the slots as you locked the back closed, and closed the slots as you opened the back. Anyway -- you snapped off two blank exposures, opened the back and put the two cassettes, joined by a short strip of film -- into a safe place, and loaded the other film in with two more of the cassettes. Then when you swapped back, you wound off two more blanks and you could continue to shoot with no risk of mis-counting and double exposures. Yes, it cost four exposures, and from a 12-exposure roll, that was a lot, but with what I usually used (36+ exposures, hand loaded) it was not that much of a bite.

I used the Contax cassettes first in a Contaflex Super (SLR with only partially interchangeable lenses -- just the front element), and missed that with all the shots I took over the years with a series of Miranda cameras, starting with the Miranda F -- the closest to a Nikon F in features that I could afford at the time. But that had a captive takeup spool, so non Contax Cassettes for that. Later I got used Nikon F bodies, and could start using them again.

[ ... ]

I tended to use Tri-X -- processed in Acufine or Diafine, and thus pushed to 800 ASA or 1200 ASA (The latter was really too low contrast for me to be happy, so even in Diafine I would only go to 800 ASA after a few rolls.) (And of course, now 800 to 1200 ISO instead. At least I never had to use DIN film ratings. :-)

I've got a Nikon D300s which I am quite happy with -- except that I would like the ability to use the full frame instead of a 1.5 crop factor, so the Fisheye and extra wide angle lenses looked normal -- but I benefit in having my long lenses behave longer by a 1.5 factor too. :-)

I've got a *lot* of lenses for the Nikon F -- only some of which I can use on the D300s. I need to make a fixture so I can modify the aperture ring on the older lenses to couple to the metering system in the camera body.

The D300s has a real flash connector, as well as the hot shoe to talk to the newer flash units -- which themselves can talk to other flashes too.

Exactly. A number of my older lenses do have the modified aperture rings, so I can use them in a somewhat less convenient metering mode in the D300s, including the 500mm f8 mirror lens, but not everything. At least a lot better than the D70, which would not talk to lenses without a built-in chip for auto metering, thus sending me back to a hand-held exposure meter. :-)

None to trade, but one of my first Digital SLRs was a Nikon N90 which had been adapted by Kodak to digital for the AP people. Not a particularly impressive number of pixels by today's standards, but when I first started using that after working with one of the little Nikon CoolPix P&S cameras, I remembered what I liked so much about SLRs vs rangefinders and P&S cameras. One of the major things is just how slow using the lens and display as a viewfinder made things, so you had to play tricks to get short term (but predictable) events. :-)

Enjoy, DoN.

[ ... ]

Hmm ... 300 amp at what voltage -- and AC or DC? It it can produce 240 VAC 60 Hz (with the usual center tap for 120 V operation as well), that sounds interesting to me. :-)

If it is purely welding voltages -- no real need for that.

Enjoy, DoN.

I wish I had a bugout retreat way the fark out in nowhere, the time to prep it, stock it, and secure it, and the money to do all the above. If so, I might have one by now.

For a 6 layer board you put the power planes on layers 2 and 5 and set the preferred directions on signal layers 3 and 4 at right angles to each other, which is standard practice anyway to make autorouting simpler. Then each trace has a constant capacitance to a power plane and minimal coupling to the ones that cross it, and thus a uniform characteristic impedance. If the logic family uses multiple voltages like ECL you may have to go to 8 layers, but I could normally build a densely packed, low-noise board with 6.

The solid planes need to be arranged symmetrically or the board will warp since it's pressed together hot and the copper and glass-epoxy shrink at different rates as it cools. I had to salvage a board another tech designed with an outer ground plane on only one side which had dished so much it would float.

When you see an unused area on a board that is crosshatched it's to equalize the thermal contraction during manufacture.

If the power and ground planes are properly bypassed either can serve about equally well as the "ground" plane, but you need to consider the noise rejection margins both ways for asymmetrical logic families like TTL. CMOS doesn't care. It's really necessary to distribute low-impedance Tantalums around the board and have 0.1uF and 0.001uF MLC caps at each device, since the two sizes have different frequency responses in the GigaHertz range.

Thermal reliefs at the power plane vias make hand soldering and rework far easier. They are the dashed rings at some pins on the Internal Ground Layer:

If the impedance is critical such as in a microwave digital radio or oscilloscope front end you may have to discuss the board's fabrication with the vendor since they can't simultaneously control the thickness of all internal layers and the overall board thickness. Something needs to squish, like the prepreg between 3 and 4 if the outer layers are controlled. It's a good idea to learn all the standard and extra-cost limits of their processes.

I haven't heard of any other experienced circuit board designers who thoroughly understood complex circuits. Management wasn't real happy paying their lab manager to perform that apparently menial task, but I proved I could deliver challenging boards that worked well the first time.

They were small rectangles of copper on the board, capacitively coupled to the ground plane. The trim was to bump them up part way between power and ground with a hand-selected voltage divider, to control the amount of charge they coupled into the cap. The S/H sample cap was as small as acceptable to better follow rapidly changing input signals.

This is what they are, if you're unfamiliar with measurement circuits:

"If the input value was permitted to change during this comparison process, the resulting conversion would be inaccurate and possibly completely unrelated to the true input value."

The project engineer was a beard, ponytail, sandals and VW bus genius Ph.D who had designed magical instruments at Keithley. He had me build a current meter to characterize dielectric absorption currents which could measure to a picoAmp in a milliSecond, which he said was state of the art. Its output was a scope display of current vs time. I had to heavily rigidize and shield it to eliminate mechanical vibration from the ultrasonic building alarm and us talking. Even the less sensitive (more stable) instruments in the production machine could detect a person's electrical field at 10-20 feet if unshielded. I used that to make it wake up and greet anyone who approached it after hours, mostly the programmers. For some reason it ignored me sitting still next to it, perhaps it accepted me as its master.

The molecular polar moment that gives a high dielectric constant causes some delayed current flow as it physically relaxes after the voltage changes. That's why electrolytics are poor for audio circuits. Dielectrics with low absorption result in capacitors that are physically large for their value, with unwanted parasitic effects. They aren't the simple, perfect components that EEs learn them as in school.

-jsw

Must have missed it, but I've never seen an F prism that wasn't smashed go for $10. If you come across a chromed one for a F that's not trashed or been dropped, pick it up for $10 and I'll buy it for $25. The fact that they did pop off and were so easy to break explains why they sell for more than the bodies these days.

What would the "plus" features be?

I may hit you up on this for the lamphouses. Just got some d6 (not sure if they're first or second gen) columns with dichroic heads, but I want them for B&W only. The fact that there are some many head options and conversions is a testament to the "simple is best" design they used. No other enlargers can be converted into so many things with so many options and gadgets available from so many third parties.

I sort of wonder where one would even get B&W paper larger than 20x24" these days unless it's on a giant roll you ordered straight from the factory. I've got a set of vacuum easels that need to be restored. Years of tape and abuse have them in a rather non-flat state.

That reminds me I need to plug in and power up the Speedotron power pack to keep the capacitors happy.

it seems that if you get something like a 4/3 mount camera, you can get adapters for most old lenses. The only adapter I bothered to but was a Mamiya 645 to Nikon F mount device. There's really no point to it, but yeah, it works if you do stop down metering of sorts.

"Michael A. Terrell" on Tue, 23 Sep 2014

03:40:23 -0400 typed in rec.crafts.metalworking the following:

Okay, I give - vvhat means "muntzed"?

-- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."

"Jim Wilkins" on Wed, 24 Sep 2014 17:54:08

-0400 typed >> "Michael A. Terrell" on Tue, 23 Sep

Ah. Applying the "KISS" principle to manufacturing. "What doesn't need to go in?"

-- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."

Chip Quick is indeed Good Stuff. I use it at least once a week. But I've never used it to solder chips in place. Is that even recommended? I'd worry about mechanical characteristics. Besides, it's pretty thick wire.

I have a look down at it flip top that fits an F - a square line grid to go with it - was for copy needs.

I see lots of Nikon gear for sale on ebay and even Amazon - going to private camera stores.

Martin