Re: How inaccurate is a 555 or 7555 REALLY?


John Fields wrote:
On 8 Dec 2006 23:02:13 -0800, bill.sloman@xxxxxxxx wrote:


Don't be silly. First you libel me, then you claim it is up to me to
prove that your unsupported libel is false.

---
If it is, you should be able to prove it.

I don't care *that* much about about your opinion.

The reason I don't want to go slogging through your stuff is because
when I did present you with evidence you'd claim that what I found
was taken out of context or that it wasn't what you meant, or any
number of other excuses to try to get out of it.

The other reason I don't want to go slogging through your stuff is
that I just don't have the stomach for it.
---

Oh, come on - this exchange has been going on for a couple of days, and
you seem to have read most of the stuff I've posted. If my posts did
turn your stomach. you'd be too busy retching to respond.

You haven't raised the stakes at all - the electron beam
microfabricator included a laser driven inteferometric stage
positioning system, and hardware to map arbitrarily scaled data
defining the inegrated circuit masks to be written onto the
interoferometer measurements. We did fall short of full generality by
assuming that the wafer/mask to be written was within two degrees of
being square to the interferometer designed grid, but our customers
assured us that that was all the tolerance we needed.

Our electron beam provided better resolution than your
photolithographuc system ever could, and was doing write on the fly. I
think you have just een comprehensively trumped.

---
Actually, it sounds pretty much like what we were doing, which was
writing patterns generated on a CAD system directly onto an alumina
wafer by ablating its surface with a laser. We also used a laser
interferometer to get the stage's position, which in our case was a
shuttle driven pneumatically back and forth, with the
interferometric data being used to get data from memory which was to
be written at that position.
---

Except that you were working at a larger scale, and slower - we had a
shaped beam electron source, which could write a shape - a rectangle in
the range 100nm to 10um -in less than a microsecond (I can't remember
the exact number) if the area was less than 1 or two square microns.
Part of the design was a gigaword random access memory with 72-bit
words plus eight bits of error correction and detection information. We
managed to publish the design

http://portal.acm.org/citation.cfm?id=45948.45966

or a stroboscopic electron microscope.

---
That doesn't sound like such a big deal. What? a couple of
detectors instead of just one, maybe two beams?
Steering magnetics? Duck soup!
---

Not if you want 0.5nsec wide stroboscopic pulses (which required an
electrostatic beam-blanking system - albeit the boss would not spring
for the wide-voltage range version on which I'm named as the inventor.
Magnetic beam blanking is nice - we used it on the old EBMF 10.5
electron microfabricator - but it won't go sub-nanosecond nor anywhere
near it.

In fact the interesting part of that system, which I first proposed in
1983 (too late to have qualified for a patent) was the "multiple flash
per cycle" feature. We could keep track of up to 1024 phase points, and
build up our waveform/image at the 25MHz sampling rate of the system
(it should have been faster, but we started off with an unrealistic
completion date which created a lot of problems) rather than the repeat
cycle of the process we were following.

And we didn't need two detectors - a sing;e relatively fast
Everhart-Thornley detector above the final lens did everything we
needed. The fast-focussed photo-multiplier tube did need a fast output
amplifier, which incorporated an analog finite-impulse response filter
built around a lumped constant delay line - a trick I've recycled a few
times since then.

Great fun, but I don't know anybody who would describe it as "duck
soup" once they understood what was going on.

---
Yup, sounds neat.
---

Not a place for a 555-addict.

---
You sure do seem to harp a lot on that anti-555 crap.

Too bad you were never successful in using it in any of your
designs, (even though it's very easy to use) since if you had been
you might actually appreciate Camendzind's genius.

It never did what I wanted done.

---
I suspect that's because there was always some reason you could come
up with why it was never satisfactory. Probably because you
considered it to be so far beneath your lofty designs that you'd
have nothing to do with it.
---

Dream on. The stuff I've worked on has included some very crude fixes -
through we did try and get rid of the cruder stuff. I was never all
that pleased with my driver for the magnetic blanking circuit on the
EBMF 10.5 - it was (just) fast enough, and didn't blow up when the
service engineers shorted the output to ground - but when I dropped in
on Cambridge Instruments (by then renamed) in the late 1990's they were
still using it, some 15 years later, with the lumped constant delay
line, and the largely capacitatively coupled drive to the output MOSFET
and all, none of which I was all that proud of, but hadn't been able to
improve.

If nothing else,
I think the use of the ratiometric voltage divider in order to
largely eliminate variations in output timing WRT supply voltage and
temperature variations was brilliant, as was the window detector
placed at the 1/3Vcc and 2/3Vcc taps of the divider.

That isn't exactly genius. Anyone whio can do enough calculus to find
minimum sensitivity conditions can demonstrate the same genius on a
wide variety of circuits. I spent a lot design time doing this on
various resistor networks when I was younger and doing serious analog
design.

Camenzind did come up with a great circuit for its time, but the
combination of crummy timer and crummy saturating switch didn't have
much to offer by 1974, when I might have used it, and has had even less
appeal since (except to people who are bit slow to learn new tricks -
when are you going to get into PLDs?).

---
If you mean use them, then when I need to, if ever. They just don't
excite me very much and I've always been able to do what I needed to
without them using cheap, easily obtained parts, so what's the big
deal.

Fewer parts, less board space, and the facility to offer more
complicated logic than you can reasonably cram in with standard parts.
Back in 1975 I thought up a way of minimising the low frequency noise
coming out of a PWM driver, and couldn't put it into a practical
circuit until 1993 when it just fitted into an ICT 7024 - it is in
figure 7 of my milli-degree controller paper in Measurement Science and
Technology, volume 7 pages 1653-1664 published in 1996.

I notice from an earlier post that you're itching to get your
hands on some of Xilinx's stuff but you're waiting for an
"opportunity" to come along? Why not just buy what you need and get
started.
---

Motivation and time. I've actually got a stick of surface mount parts,
but solder has probably already oxidised the point where they will be a
swine to mount - the idea that I was working out ddn't work out quite
the way I expected, and the next critical point involves doing a messy
mechanical drawing with QCAD, which I've yet to get working.

YMMV, but I think you kind of begrudge him his success because you
think you're ever so much smarter than he is and yet...

I don't begrudge Hans Camenzind his success. Try to find some evidence
to support that daft allegation.

---
Just a feeling...
---

I''ve also got no reason to suppose that I'm smarter than Hans
Camenzind, nor have I ever made any such ridiculous claim.\

---
How about the: "That isn't exactly genius."... paragraph above?

The application is the thing. The technique he used to get the
application to work is sort of routine for properly trained engineers.

You seem to be setting yourself up as a judge of what constitutes
genius and what doesn't, thereby putting yourself above him by
declaring his work "not genius". Strangely, what I said was that it
was "brilliant". The "genius" part was in a different context.
---

The arguement is about where the ingenious innovation was made. You
seem to be over impressed by elementary calculus, and insufficiently
respectful of of the trick of finding the right combination of features
for the time.

You don't seem to have a particulary secure grasp of reality, do you.

---
Not according to you, but then I always keep a saltshaker around
whenever I read your stuff.

Nobody is asking you to believe the bits you don't understand. That
would be unreasonable, though you'd profit by a less skeptical
approach.

--
Bill Sloman, Nijmegen (but in Sydney at the moment).

.

Relevant Pages

  • =?UTF-8?B?2YHYsdmI2LQg2YXYrNmF2YjYudmHINqp2KfZhdmEINqp2KrYp9io2YfYp9uMINmF2YfZhg==?= =?UTF-8
    ... Circuit - Electrical Circuit Theory And Technology 2Nd Edition, ... Circuit - Digital Logic Circuit Analysis and Design - ISBN ... Circuit - Analog Integrated Circuit Design - Handbook of Operational ... Electromagnetics - A treatise on electricity and magnetism, ...
    (sci.math.num-analysis)
  • Re: TRNG with 18 Mbit/s using Thermal Noise
    ... And it is a complete design, not just the noise source, or a theory ... in zenner mode as a noise source, just like most of the circuits here. ... Circuit technique wise, I used a small amount of feedback to broaden the range of acceptable transistors while staying clear of instability and I pointed out that because there was capacitor coupling between stages, there would be some level of autocorrelation - which I minimised by making the time constants involved quite large. ... Assuming this is feed into a sound card then: The low frequency cut off will make autocorrelation effects more obvious. ...
    (sci.crypt)
  • Re: Who is your favourite electronics guru?
    ... John Fields wrote: ... I suppose every time you post a design here you ... from the circuit diagram presented in the book - nothing in the book ... got to meet and work with a great many professional engineers. ...
    (sci.electronics.design)
  • Re: Software for a beginner to design and learn about circuits with?
    ... >>Go to the library and check out a book on analog circuit design. ... a simulator and don't understand digital or analog, ... Never said you shouldn't do bench work along the way. ...
    (sci.electronics.design)
  • Re: Help with 3 stage timed controller
    ... since I even attempted any type of circuit design). ... relays are running a vacuum pump and opening a solenoid controlled air ... hour - and he certainly will not pay for a PLC to replace what is ...
    (sci.electronics.design)