Re: How inaccurate is a 555 or 7555 REALLY?

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.

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.
---


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.
---


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.
---

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. 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.
---

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?

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.
---

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.


--
JF
.

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