John Curl's Blowtorch preamplifier part II

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Here is a photo

Is it for plasma confinement Richard?



Ed, check if the noise is due to the probe’s ground clip pick-up point.

On a side note, long ago, you had asked me (I saw your post with a great delay) what I find as an alternative to a choke input psu.
What I find that can work as such, is cascaded CRC.
Multistage, each stage with different time constant and C progressively increasing towards the load side.
Apart for higher harmonics decreasing more, the arrangement deals well with the problem of rectification frequency ripple (2xmain’s freq.) increasing in amplitude when the amplifier (that the psu is feeding) amplifies low frequency music (sustained notes) content.
Typical PSUs with a lot of C after the bridges and not CRC arranged, are vulnerable to this.
See attached some measurements on a psu of a well regarded power amp (amp is 2x150W/8R. In these measurements, I drive only one channel and up to 100W. I probed on the + side of the psu).
To see the effect, I link two oscilloscope screenshots taken years ago from a psu of the same kind of another amp. http://www.diyaudio.com/forums/attachments/solid-state/71167d1159649591-simple-killer-amp-constructor-thread-ripple-modulation.jpg

George
 

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Near all famous designers and architects agree on one thing: a good design is when the form is a natural consequence of the function. It is the same for ideas: " Ce qui se conçoit bien s'énonce clairement."
It is always amazing to see how beautiful are objects with high technical constraints, planes, submarines, rockets, race cars, when no marketting departments impose some stupid fashion specifications.
It is always interesting to see how the best printed boards designers (we have some on this Forum, like Sir Alex mm), when they took in consideration all the technical aspects (ground issues, symetry, parasitic inductances etc.) produce very nice looking PCBs.
There is a general law in the universe: Everything follow the easiest way. Perfect combination of "easiest" everywhere brings to simplicity and economy.
 
It is always amazing to see how beautiful are objects with high technical constraints, planes, submarines, rockets, race cars, when no marketing departments impose some stupid fashion specifications.

Easy to say they're not, if the degree of design liberty is limited to the shape of a window or a wing tip.
Try throwing a brick through the air with minimal thrust SFC.

Styling may be forced to play an inferior role in airplane, rocket, and race car design, but aesthetic appeal sells there just as in any other line of business.
 
High opinions, from 'Monday morning quarterbacks'. '-) A 'sealed' construction is a necessity for the best operation of the CTC Blowtorch. It keeps the impurities from the outside air from getting inside the unit. It keeps the inside, dust free. It keeps (once it is fully warmed up) changes in temperature from adding further 1/f noise or creating dynamic offsets. (Just blow on a Vendetta Phono board sometime or just lift the lid while it is connected to test equipment.) The only thing that I regret is not adding some sort of sulfur 'trap', something recommended to me by Ed Simon. (Next time!)
 
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Styling may be forced to play an inferior role in airplane, rocket, and race car design, but aesthetic appeal sells there just as in any other line of business.
Yes, it is true. Easy to see how aesthetic was different, during the spatial race between USSR and USA. Our technical approaches are deeply influenced by our environment, art, culture, etc. But it is in an unconscious and natural way. Like trees tend to look different under different winds. Not marketing trying to sell apples for oranges.
In a way, i believe science fiction deeply influence science, like language influence our way to think.
 
High opinions, from 'Monday morning quarterbacks'. '-)
And you are surprised to be flamed, sometimes ?
Dust or thermal effects are nothing to do with "plain machined aircraft grade aluminum".
My 4 CPUs 5Ghz computer is full of dust, enormously ventilated, with huge dynamic temp differences, and run like a clock.
It was cheap, too.
 
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Boeing has solid blanks cast for small parts such as wings! If you look at the economics, the aluminum blank costs around $1.65 a pound and the chips sell for $.95. A press release I quickly found mentions a bit about their milling capability.

"Commercial Airplane Group's newest fabrication facility today began turning out the first components this massive plant will make to support production of the company's jetliners, Boeing (NYSE: BA) announced today.

The approximately 100 employees on duty began production of a wing skin panel for a Boeing 747 and a Boeing 767 upper panel stringer using huge milling machines that will eventually make parts for all Boeing models except the 737. Production of parts for Boeing's newest jetliner, the 777, is scheduled to begin at the Frederickson site in mid-summer.
Called Skin and Spar South, the 935,000-square-foot (86,861- square-meter) facility is located in Frederickson which is about 16 miles (25 km) southeast of Tacoma and 44 miles (70 km) from Seattle.
Part of Boeing Commercial Airplane Group's Fabrication Division, the Frederickson facility was designed to supplement a wing skin and spar factory in Auburn, Wash. where Boeing's Fabrication Division is headquartered.
Skin and Spar South will eventually employ 350 to 400 workers when it reaches full production by the end of 1994.
Equipment in the Frederickson facility includes milling machines that measure up to 270 feet (82 meters) and are capable of milling parts 105 feet (32 meters) long.
Skin and Spar South is the first facility to be activated at Boeing's Frederickson site. Last November ground was broken for a second facility, a 432,000-square-foot Composite Manufacturing Center (CMC) which will fabricate parts made of carbon fiber reinforced plastics. The CMC is scheduled to begin operations in February 1993.
Boeing has also announced plans for three more expansion phases to build various manufacturing and office facilities over a period of about 20 years. Formal initiation of each additional phase will depend on business conditions and market demand.
-0- 4/15/92
/CONTACT: Mike Broom of Boeing, 206-931-5834/
(BA) CO: Boeing Commerical Airplane Group ST: Washington IN: AIR SU:
"
 
Here is a photo I took: Here's a vacuumed tube for you-- its about 30 feet long and the beam current is 10,000A or more. Can anyone guess what it is called, in general? [ clue- the view is from the target -plate- end looking towards back towards the source (not shown in place)].

And, what are all those metal stainless steel donut-like rings used for?

Another clue: JN mentioned wigglers once upon a time.

-RNM

Wigglers? Well, I was watching a you-tube video of some hula dancers at the time.

30 feet? It looks like one section is about 15 feet, with 5 sections, each with a gate valve.

The period appears consistent, so I'd eliminate an RFQ.

I can't see any waveguides, but that could be the angle.

The flanges could mean anything from neo plates to small rf cavities.

My first guess is an FEL outta SLAC.

jn
 
I need this sort of exterior fit and finish to compete in the marketplace. I am open to 'serious' suggestions.
List your technical requisites (seriously) on a paper. The answers will come automatically if you are smart.
About "look and feelings" nice mechanical assemblies are a must if you highlight them.
And, for Emirs and other nouveaux riches, aluminum is certainly not a noble metal for a front pannel. I would prefer thick tinted glass, granite, marble, Nickel, Coper, wood, leather etc.
As far i'm concerned, i would try something technically 'fashionable' and high tech, like "carbon fiber".
 
I need this sort of exterior fit and finish to compete in the marketplace. I am open to 'serious' suggestions.

Start with a good industrial designer. The Blowtorch is about as bland as a slice of Wonder bread. Your friends at Constellation at least had the good sense to go to Neal Feay, though I have to say I don't find their work to be much more inspiring. It's still in the rather bland, "big hunk o' metal" camp.

se
 
List your technical requisites (seriously) on a paper. The answers will come automatically if you are smart.
About "look and feelings" nice mechanical assemblies are a must if you highlight them.
And, for Emirs and other nouveaux riches, aluminum is certainly not a noble metal for a front pannel. I would prefer thick tinted glass, granite, marble, Nickel, Coper, wood, leather etc.
As far i'm concerned, i would try something technically 'fashionable' and high tech, like "carbon fiber".

This is what inspired my current project. A Gody Model 23 crystal radio from the early 1920's. Wood, Ebonite, Bakelite and brass. Some 90 years hence I still find it a thing of beauty.

se
 

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John,
I understand your point of trying to maintain a constant temperature if you have designed for that and can control the set point for a given result. But an aluminum enclosure of similar shape that is made of multiple pieces does not have to necessarily have high leakage if that is one of your goals. The fit tolerance of a typical machined part would not let any more ingress of dust into the enclosure than a one piece machined billet.

If we were talking about a magnetic motor structure then yes every connection of two materials will create an additional boundary condition interfering with the circular flow of a magnetic field causing additional eddy current production.

What is it about a sulfur trap that I must have missed along this long tortuous conversation?

On the industrial design side I have to agree with Steve Eddy that a simple rectangular block of aluminum has no inherent design factors that makes it look like a beautiful product. Without the few control knobs it would look even more like nothing but a block. As someone who has done industrial design for many years that isn't anything that a child wouldn't come up with using building blocks. With a billet of aluminum you could do much better.

Simon,
You seemed to be trying to infer that the wings skins of those Boeing planes are made from solid billets of aluminum. Having worked for a company that was a subcontractor for Boeing and Lockheed and many others I can assure you that is far from the truth. The skins are made of sheet material and are drop punch formed with massive stamping machines and die sets. After forming a process called chemical milling was used to remove material is specific areas. We had mills with over 100 foot beds, I think our largest was about 160 foot, and these were used for machining assemblies and not billets of aluminum.
 
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It needs dovetails at the corners. First, fit some maple in, then go with bloodwood. The small sides should be lacewood.

We're going with box joints. Here's a preliminary chassis in eastern hard rock maple. Going to use some slipfeathers in the corners of the bottom piece, and there we can use things like bloodwood.

se
 

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