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Old 5th October 2012, 11:07 AM   #7371
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Quote:
Originally Posted by tvrgeek View Post
I seem to remember a story at a Polish mathematician theorized what is basically a FET long before semiconductors were invented. Something like, "if you had a material that behaved like this, you could do that with it" kind of thing.
I had a chart published in about 1908 listing many ten's of semiconductor materials . I think 1880 was when Siemens produced selenium devises commercially ?

I read that a French engineer claimed to have perfected television in the 1880's using selenium cells . Some say Baird knew of this and added amplification . If I am right both worked by optical scanning ?

https://en.wikipedia.org/wiki/Julius_Edgar_Lilienfeld
History of Communications - Historical Periods in Television Technology: 1880-1929
https://encrypted.google.com/patents...5&hl=en&lr=all
http://www.computerhistory.org/semic.../timeline.html

Last edited by nigel pearson; 5th October 2012 at 11:28 AM.
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Old 5th October 2012, 11:48 AM   #7372
DF96 is offline DF96  England
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Originally Posted by SY
With micro-machining, heaters are not needed.
OK, cold cathodes (field emission?). Does that give enough emission to form a decent space charge so shot noise is suppressed? If not, how do we make low noise UHF/microwave receivers? Also, how does flicker noise scale with device size - could we find (as with GaAsFETs) that flicker noise extends up to VHF frequencies so IF and baseband circuitry is too noisy?
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Old 5th October 2012, 01:12 PM   #7373
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What about the DF96 ?
http://www.r-type.org/exhib/aad0032.htm
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Old 5th October 2012, 01:22 PM   #7374
DF96 is offline DF96  England
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Hey, someone has named a valve after me!!

The DF96 only works in the HF region, so no good for cell phone front ends. It is the same size as other B7G valves so you would need big pockets.
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Old 5th October 2012, 01:35 PM   #7375
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What were your parents thinking ?
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Old 5th October 2012, 02:17 PM   #7376
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http://www.porticus.org/bell/pdf/bra...b_notebook.pdf
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Old 5th October 2012, 03:09 PM   #7377
SY is offline SY  United States
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Quote:
Originally Posted by DF96 View Post
OK, cold cathodes (field emission?). Does that give enough emission to form a decent space charge so shot noise is suppressed? If not, how do we make low noise UHF/microwave receivers?
Paralleling. My buddy who makes these devices can array hundreds of them in an amazingly small bit of silicon. He's using them for some sort of esoteric detector which he can't tell me about.
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Old 5th October 2012, 03:57 PM   #7378
bcarso is offline bcarso  United States
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Originally Posted by SY View Post
Paralleling. My buddy who makes these devices can array hundreds of them in an amazingly small bit of silicon. He's using them for some sort of esoteric detector which he can't tell me about.
Sensible. Space charge smoothing is, after all, only a relatively small effect, if still welcome. There are probably also some ingenious ways to make beams more monoenergetic.

The next step will be to utilize entanglement to eliminate cable distortions. And someday, we will have filters and systems with anticipatory responses.

Then my alarm will go off.
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Old 5th October 2012, 03:58 PM   #7379
SY is offline SY  United States
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No, in that case, your alarm would go off first.
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Old 5th October 2012, 04:06 PM   #7380
dvv is offline dvv  Serbia
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Are you ready to eat your hat, бэби?
Sorry, I don't wear a hat, it impairs natural air flow cooling.

Believe this or not, but I greatly regret we do not live managavly near to each other. I suspect we would spend many a wonderful afternoon nibblig at each other on the subject of trannies vs toobes. We would need power, so we would use a neutral technology device in form of an honest to goodness coal powered grill, permitting electricty only to cool off the beer and/or wine.

We could have others from this forum there as well, and I do believe that would be a good thing. John could brood on the subject of op amps, Wayne could expound opn the virtues of a 0.1 Ohm loudspeaker, and in general, I guarantee we'd all have a good time.
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