On Mon, 18 Mar 2002 17:09:59 -0800, Bob Ammerman wrote:
<topic tag changed>
>I must say I have to think twice when I see caps valued in nF. Where and
>when I learned my electronics (in the US, in the 70's) there weren't no
>such thing as a nF.
>
Same here.
>It is the better way 'tho.
>
I don't know that I can really agree on that point. I lean toward the
'readability factor'. It's pretty tough to confuse a 'p' with a 'u' on
a schematic but it's just too easy to mis-read an 'n' for a 'u' and
vice versa.
Example: The Microchip documentation error that started this whole
thread. Somebody's mis-reading of an 'n' as a 'u' caused the error.
Regards, Bob
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"4n7" is not a form in common usage
in many US firms. I hadn't seen it
except in European 'works' ...
In what used to be most mainstream RF work
most of the critical or 'tuning' caps
were in the picoFarad range with the
DC bypass caps in the microFarad range ...
the ease of identifying the difference in
the two on a schematic at a glance is helpful.
When it comrs down to identifying just one
or two caps in a digital circuit the
benefits are lost.
Contrast a receiver schematic sheet full
of 2.7Pf, 3.3pF, ... 27pF, 33pF ... 390pF caps
versus bypass cap values of .005uF, .05uF, .01uF,
et cetra.
>"4n7" is not a form in common usage
>in many US firms. I hadn't seen it
>except in European 'works' ...
>
>In what used to be most mainstream RF work
>most of the critical or 'tuning' caps
>were in the picoFarad range with the
>DC bypass caps in the microFarad range ...
>the ease of identifying the difference in
>the two on a schematic at a glance is helpful.
>
>When it comrs down to identifying just one
>or two caps in a digital circuit the
>benefits are lost.
>
>Contrast a receiver schematic sheet full
>of 2.7Pf, 3.3pF, ... 27pF, 33pF ... 390pF caps
>versus bypass cap values of .005uF, .05uF, .01uF,
>et cetra.
>
>Jim
>
>
>
At 02:16 PM 3/19/2002 +1200, you wrote:
>> And Real Men Used Vacuum Tubes!
>
>Thanks for the mental picture. Gonna take me
>all day to shake that one out
>
>--
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>
>
Larry Bradley
Orleans (Ottawa), Ontario, CANADA
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> Oops!
>
No worries. You're having a good time by the way
>
> At 02:16 PM 3/19/2002 +1200, you wrote:
> >> And Real Men Used Vacuum Tubes!
> >
> >Thanks for the mental picture. Gonna take me
> >all day to shake that one out
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> And Real Men Used Vacuum Tubes! (can you picture a vacuum-tube processor
> with the power of a PIC?)
Yes, I can!
I just purchased a 1955 reprint of a 1953 book
"Faster than Thought" edited by B V Bowden.
This describes the state of the art of Digital Computers as at 1953.
Some of these machines would be around PIC power.
Each chapter is written by an expert in the particular computer or aspect
discussed.
Most people would be amazed how many different types of computer and methods
of doing various tasks there were.
Memory was an amazing subject. Mercury tanks, wire delay lines, Cathod eRay
Tubes (data is stored in the phosphor and a 1 or 0 measured by how much beam
current is drawn when you write to the location of concern - dynamic memory
needing refresh and with destructive read needing suitable post read
action - you can SEE your data sitting in the memory. And much much more.
A superb book to read for those wanting a real feel for where the computing
industry has come from. Even papers (chapter) on computers playing games
such as chess and draughts. Also contains a signifcant amount of material on
Babbages difference engine and a copy of Countess Ada Lovelace's paper on an
example of programming it.
Includes:
History and theory - 5 chapters
Individual chapters on computers made at Manchester, Cambridge, Harwell,
Telecom research Estanblishment (UK), Imperial College, Royal Aircraft
establishment, Birbeck College, USA (short comments on Harvard, ENIAC, IBM,
EDSAC, ACE, Princeton, MIT, UNIVAC machines).
Applications - 12 chapters including one on games contributed to by THE
Allan Turing, Bowden himself (Ferranti), Miss Audrey Bates (Ferranti) & Mr C
Strachey (NRDC)
Russell McMahon
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> Anyone remember the old mica capacitors that looked a bit like dominos
> with dot codes?
Yep, I cut many of them out of old TV's and radios to build my stock of
parts.
I remember thinking is was strange to use the 'resistor' color code to
determine
the value of a capacitor.
Of course, today I never depend on reading the value on a cap out of
circuit. I always
stick it into my capacitance meter to make sure.
The little dots sure made it easy, but can you imagine the poor worker in
the factory painting them on, one by one? ;-)
Then there were the very old bar resistors I remember in stuff I took
apart as a kid. IIRC the body color was the first digit, end color was
the second digit, dot color was the multiplier.
