OT: Bush Thugs Rough Up Grieving Mother of KIA

[Mike]

On Thu, 23 Sep 2004 13:27:51 GMT, Kevin Aylward wrote:

John Woodgate wrote:
I read in sci.electronics.design that Kevin Aylward
salesEXTRACT@anasoft.co.uk> wrote (in
qaw4d.64767$U04.25646@fe1.news.b lueyonder.co.uk&gt about 'Ping Kevin
Aylward - re GUY MACON', on Thu, 23 Sep 2004:

Although not having a degree by itself, is not a measure of worth,

Right.
I
would suggest than those here with degrees, fully understand that
such a background as this, makes the candidate have no realistic
chance of making any worthwhile contribution or comments on
technical physics matters.

Not necessarily.

Not necessarily, but 0.00000000001% of a chance.

With these odds, even if every person on Earth had failed to obtain a
degree, the odds of one single person satisfying the conditions are less
than 1 in 1000.

Further, this incredibly low probability is purported to abruptly change to
a vastly larger probability upon receipt of a degree.

-- Mike --

 

[Winfield Hill]

Winfield Hill wrote...

prabha_kar@hotmail.com wrote...

I want to measure sub-nanoampere (upto about 1pA), DC current.
-Can anyone help me selecting the circuit and components to design
such an instrument?

Your first task should be to obtain some high-value resistors.
One good possibility is to purchase an old Keithley electrometer
on eBay, and scavenge the teflon switches and resistors.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3840791292

You can tear apart the 610, leave it as is and use it, or
convert it to a solid-state machine, using one of the NSC
opamps I mentioned. I have a schematic of Keithley's 610A,
which has switch wiring and architecture similar to the 610B.


--
Thanks,
- Win

(email: use hill_at_rowland-dotties-org for now)

 

[Phil Hobbs]

Rene Tschaggelar wrote:

Phil Hobbs wrote:

Rene Tschaggelar wrote:

Yannick wrote:

I was thinking of using the OPA695 current feedback amplifier for my
transimpedance amp. This amplifier is capable of delivering much more
gain over a much larger bandwidth... I also see the equi current noise
at the input is much larger then with the FET input opamps like the
OPA657 but if the signal is large enough (lets assume you have an
avalanche photodiode) isn't it better to use such a current feedback
amp in stead of a voltage feedback?

The reason why i am considering this is because i never will be able
to measure 300-500Mhz with the voltage feedback amps. I want higher
frequencies because this will give me far better distance resolution
with phase measurement due shorter wavelength.





A repeatedly discourraged solution in s.e.d. :
In case of sufficient light (few mW average) take a
100 Ohm and dump the photocurrent from the reverse
biased photodiode into it.
Take this signal and go capacitive coupled through a
MAR6 (20dB) and a MAR3 (13dB). Both have 2GHz bandwidth
and are available for 1$ or so.


(Since I regard myself as one of the chief disparagers of suboptimal
photodiode front ends, here and elsewhere....)

This approach is fine if speed and low cost are the primary concerns,
or if there's lots of light, just as you say. I built something
almost exactly like this a month ago, except that I just dumped the
photocurrent right into a MAR-3 with nothing else on the input side.
I used a Thor Labs FC-ferruled InGaAs photodiode, and build the whole
thing dead-bug fashion on a piece of FR-4 set in to the lid of a
die-cast aluminum box.

On the other hand, I'm putting in about 1 mW peak power from a
picosecond laser--the circuit was part of a new triggering setup. It
has a 200 ps rise time, which is pretty good for the price. (Rings like
a SOB, too, but all I care about is the first negative-going edge.)


You mean 1mW average from a picosecond laser ?
That still makes 10W peak or so.
No terminating resistor ? No capacitive coupling ?
That's what I call blunt.
Actually also with the picosecond setup and 5mW average
or so on the diode, we're using an AEPX65 to phase lock
the pulse with a jitter somewhat below 1ps.
I wish I could use an FC coupled one.

Rene

No, it's 1 mW peak--I'm just sticking a single mode fibre behind a ND 2.5
filter, right in the unfocused beam. The actual laser peak laser power is
more like 10 MW. Fibre optics works great when your optical pulses are only
a quarter of an inch long.

My rep rate is only 20 Hz, and the flashlamp jitter is probably hundreds of
nanoseconds, so I have to synchronize on each pulse separately.

The MAR-3 has a low, resistive input impedance, and the photocurrent pulse is
unipolar and has a very low duty cycle, so the net effect is very nearly
identical to capacitive coupling (within 1 part in 10**10). Adding
additional components on the input would just have added stray capacitive
loading without changing anything.

Cheers,

Phil Hobbs

 

[John Fields]

On Fri, 24 Sep 2004 15:32:22 +0100, Terry Pinnell
<terrypinDELETE@THESEdial.pipex.com> wrote:

Tony Williams <tonyw@ledelec.demon.co.uk> wrote:

Early versions of Autosketch were quite intuitive
and easy to use. AFAIR, A'Sketch V.5 is the one
that many people bitterly regret 'upgrading' to.

Hope I wasn't partially to blame! Your post reminded me I'd written
reviews of v5 for PC Plus and What PC in May '98. Looking them up, I
see I wasn't particularly critical in either <g>.

Mind you, I see I finished one piece with this, which perhaps squares
with John's comments about counter-intuitiveness:

"Finally, one other quite revolutionary change in this release is the
replacement of Action/Object operation by the Object/Action approach -
in which you first select your object (such as a rectangle), and then
act on it (say, to fill it with a solid red colour). This is by far
the more common method, and is faster and generally more popular - but
no doubt there will be howls of protest from some classic AutoSketch
users."

---
Somewhat akin to the difference between RPN and algebraic(?) input on
calculators?

--
John Fields

 

[John Larkin]

On Fri, 24 Sep 2004 11:10:06 -0400, Phil Hobbs
<pcdhSpamMeSenseless@us.ibm.com> wrote:

The MAR-3 has a low, resistive input impedance, and the photocurrent pulse is
unipolar and has a very low duty cycle, so the net effect is very nearly
identical to capacitive coupling (within 1 part in 10**10). Adding
additional components on the input would just have added stray capacitive
loading without changing anything.

Cheers,

Phil Hobbs

The Sirenza SGA-series (SiGe) mmics are very nice. One of them, the
SGA-3586 actually - are you sitting down? - has a 50 ohm input
impedance!

John

 

[Ken Smith]

In article <2ec4xwB3s8UBFwZm@jmwa.demon.co.uk>,
John Woodgate <noone@yuk.yuk> wrote:

I read in sci.electronics.design that Clifford Heath <cjh-
nospam@nospaManagesoft.com> wrote (in <1095987661.922719@excalibur.osa.c
om.au&gt about 'Sill trying to get ME to install', on Fri, 24 Sep 2004:
Dirk Bruere at Neopax wrote:
What I have needed in the past is s/w that can do a really nice 2D plot,
with self scaling axes. Ideally, freeware source so I can drop it into
other apps.

gnuplot is the standard answer, but it is a little primitive.
Give it a whirl, but work through the examples first.

Doesn't it require Linux? Is there a Windows version?

Yes I've downloaded the win version and it seems to function. I don't
know enough about it to say it works identically.

--
--
kensmith@rahul.net forging knowledge

 

[Ken Smith]

In article <7UMbzAV3tzUBFwIt@jmwa.demon.co.uk>,
John Woodgate <noone@yuk.yuk> wrote:

I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <civ7ht$ci0$3@blue.rahul.net&gt
about 'Sill trying to get ME to install', on Thu, 23 Sep 2004:

I often want to graph about a 1^6 points so a chart that could do it
would be very helpful.

Do you not find that they tend to crowd together a bit? Not much scope
for a nice curve, I would think.

You plot them down the page along about 50 feet of continuous paper on a
dot matrix printer and they look great. As stated elsewhere I have a
program that does just that.

The program also makes a scrolling display of the chart on the CRT so you
can sit and watch it like a sped up movie.

--
--
kensmith@rahul.net forging knowledge

 

[John Woodgate]

I read in sci.electronics.design that Kalman Rubinson <kr4@nyu.edu>
wrote (in <i0d8l0l11co496c4sehisf7v31osqqunfp@4ax.com&gt about 'safe
electronic brain stimulator', on Fri, 24 Sep 2004:

Good description but leave the cortex out of it the control mechanism;
it's the brainstem.

You are correct. There!
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Winfield Hill]

John Larkin wrote...

Phil Hobbs wrote:

The MAR-3 has a low, resistive input impedance, and the photocurrent pulse
is unipolar and has a very low duty cycle, so the net effect is very
nearly identical to capacitive coupling (within 1 part in 10**10).
Adding additional components on the input would just have added stray
capacitive loading without changing anything.

The Sirenza SGA-series (SiGe) mmics are very nice. One of them, the
SGA-3586 actually - are you sitting down? - has a 50 ohm input impedance!

Be still my beating heart.


--
Thanks,
- Win

(email: use hill_at_rowland-dotties-org for now)

 

[Bob Stephens]

On Fri, 24 Sep 2004 16:34:33 +0100, John Woodgate wrote:

(not that these were set up by the people now disparaged as 'ragheads!).
^^^

note?

 

[Ken Smith]

In article <Xns956DDDCF03FFDjyanikkuanet@204.117.192.21>,
Jim Yanik <jyanik@abuse.gov> wrote:
[... me ...]

Universities are populated by well educated people. If you call to
views of the well educated "liberal" then the statistic I quoted
becomes a no-brainer.


Well,in this case,"liberal" actually translates to "socialist" or
Communist.

Which case? Whos doing this translation? Why is "socialist" in quotes?

I have to admit that I haven't been on a campus in 5 years. Are you
saying that they've been invaded by Communists?

--
--
kensmith@rahul.net forging knowledge

 

[John Woodgate]

I read in sci.electronics.design that John Woodgate <jmw@jmwa.demon.cont
raspam.yuk> wrote (in <QByBWzCJ6DVBFwl+@jmwa.demon.co.uk&gt about 'Ping
Kevin Aylward - re GUY MACON', on Fri, 24 Sep 2004:

(not that these were set
up by the people now disparaged as 'ragheads!)

That should read:


NOTE that these were set up by the people now disparaged as 'ragheads!
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Rolavine]

The Fred Bloggs - Don Pearce dialogs are a hoot! It reminds me of that old
'point counterpoin't takeoff on the original Saturday Night live.

"Dan, you overweight porker"
"Jane, you ignorant slut"

I can't wait for them to get to the "Your Mom's so ugly" jokes.

Rocky

Rocky

 

[Don Pearce]

On 24 Sep 2004 16:29:02 GMT, rolavine@aol.com (Rolavine) wrote:

The Fred Bloggs - Don Pearce dialogs are a hoot! It reminds me of that old
'point counterpoin't takeoff on the original Saturday Night live.

"Dan, you overweight porker"
"Jane, you ignorant slut"

I can't wait for them to get to the "Your Mom's so ugly" jokes.

Rocky

Rocky

Sorry Rocky, but my interest in the thread has died.

OK, then - if you insist "Your mom's so ugly that you were a test tube
baby even though she is fertile."

d
Pearce Consulting
http://www.pearce.uk.com

 

[Rolavine]

From: Fred Bloggs

Tom Seim wrote:

Now, what are you going to do, call me a "moron" again? Got to think
of something better than that.

Tom

For variety we could subsitute: fool, dunce, dullard, dullhead, dumbell,
dummkopf, dummy, idiot, ignoramus, simpleton, imbecile, cretin, ament, feeb,
half-wit, Pavlov Pup, drugged, high, hopped-up, spaced-out, stoned, tripping,
wiped out, zonked, reduced, degraded, deluded, ass sniffing weiner, bicycle
seat licker, booger munching munchkin, wind up toy, drooler, or rent boy, if
you think that would help.

Honestly, lets stop calling each other names. Also, when we talk about each
other as 'people of your kind, or 'your ilk' it is a bit absurd and general. I
will try to stop, and I have been guilty of it.

Rocky

 

[John Larkin]

On 24 Sep 2004 08:46:56 -0700, Winfield Hill
<Winfield_member@newsguy.com> wrote:

John Larkin wrote...

Phil Hobbs wrote:

The MAR-3 has a low, resistive input impedance, and the photocurrent pulse
is unipolar and has a very low duty cycle, so the net effect is very
nearly identical to capacitive coupling (within 1 part in 10**10).
Adding additional components on the input would just have added stray
capacitive loading without changing anything.

The Sirenza SGA-series (SiGe) mmics are very nice. One of them, the
SGA-3586 actually - are you sitting down? - has a 50 ohm input impedance!

Be still my beating heart.

Well, I was pleased. Most MMICS seem to run low, mid-high 30's often.
I wonder why... maybe that optimizes gain or noise figure? The 3586
can be tuned to exactly 50 ohms by fiddling the device current; it's
the only MMIC I've found that can. Add a small series RC from input to
ground, and it becomes a very good bounceless wideband match.

John

 

[Rene Tschaggelar]

Phil Hobbs wrote:

No, it's 1 mW peak--I'm just sticking a single mode fibre behind a ND
2.5 filter, right in the unfocused beam. The actual laser peak laser
power is more like 10 MW. Fibre optics works great when your optical
pulses are only a quarter of an inch long.

My rep rate is only 20 Hz, and the flashlamp jitter is probably hundreds
of nanoseconds, so I have to synchronize on each pulse separately.

The MAR-3 has a low, resistive input impedance, and the photocurrent
pulse is unipolar and has a very low duty cycle, so the net effect is
very nearly identical to capacitive coupling (within 1 part in 10**10).
Adding additional components on the input would just have added stray
capacitive loading without changing anything.

Interesting that you get some signal at all from 1mWpk.
And with a straight input to a MAR3

Rene

 

[Ken Smith]

In article <LABXmTBFZCVBFwXl@jmwa.demon.co.uk>,
John Woodgate <noone@yuk.yuk> wrote:
[...]

I wouldn't have thought you needed a long piece of paper to plot 1^6
points. (;-)

It's called 'gestalt'; you expect to see '10^6', so that is what you
read. But that is not what is written.

I even had to read the 1^6 line twice to see it. Its amazing how what you
expect to see can bias what you do see.

Hmmmm... If I didn't expect to see this office, would is disappear.
(gears grinding and smoke from ears)
Nice palmtrees!

--
--
kensmith@rahul.net forging knowledge

 

[colin]

"Yannick" <yannick_de_wit@pandora.be> wrote in message
news:cc50d220.0409240628.dfe758c@posting.google.com...

ofcourse, but if you take everything for one fixed frequency, say
20Mhz then you can calculate the signal noise ratio in function of Rf.
then it seems that when rf is infinite only voltage noise of the
amplifier is in the game, and because the feedback impedance is then
only from the feedback capacitance you get highest S/N ratio. If i
calculate the optimal Rf for the largest transimpedance gain
(D(Af)/Drf = 0 => Rf = 62k) i get 62K but for S/N ratio Rf has to be
as high as possible. The only reason you need a lower value of Rf is
to get like you say a flat frequency response.



No this isnt what i am missing, i calculated the Signal as Sout =
ID*Af(Rf) with ID = 177na (calculated this for 10meter distance with
avalanche photodiode...)

Then i calculated the noise as Nout = Ieq(Rf) *Af(Rf)

then i calculated the SIgnal noise ratio as S/N = 20*log(Sout/Nout)

i plotted this in a X-Y plot with S/N on the y as and Rf on the x as
and it this gives a graph wich keeps increasing (although flatter and
flatter) for an increase in Rf , and the formula for Af(Rf) is
correct, it matches perfect with the Pspice simulation , soo i cant
see any errors...

yes i agree, sory i misunderstood slightly, the resistor inevitably adds
noise so leaving it out means you have less noise,
wich is what i think i said as well anyway, but i thought you were still
meaning the higher frequency wich you mentioned in the previous paragraph. i
wasnt fully awake when i read it lol.

If i were you i would measure what signal you get when u reflect it off a
target, my estimate of 10% reflected back towards the lense was pure
gueswork. the real chalenge comes when u have a smooth dark surface that is
angled away from the detector.

177 na at 20 mhz acros 10pf = 140uv wich sounds ok compared to the 18uv
noise for a 20mhz bandwidth from the amplifier, but this wil stil give u
quite a bit of jitter, of course this can be averaged out over many
milliseconds, but ive found it quite dificult to get as good as results as i
wld expect from this simple calculation. i have quite narow bandwidth too,
but i find most of the problem lies in noise picked up. in particular my
high voltage bias generator frequency seems to apear a lot on the signal,
despite a sheild over the rf input section and a sheild over the hv
generator and using a 7 stage multiplier so i need a lower voltage of the
200khz squarewave to the step up transformer, however you may have les
problem here as my input is tuned so is very much higher impedance.

Also i mentioned in another post one day i had it resting on my keyboard
wich is wirless and so was transmiting constant keypresses at 27mhz wich
swamped the output and had me looking for the cuase for ages. i normaly
switch off my computer/monitor flourescent lamp etc. when i try to measure
low noise performance, but hadnt considered the keyboard.

you sugested using a sinewave wich i gues would make more sense as would not
puting the thing so dam close to the detector like i did lol, i just thought
best to have a short a track as posible at 250v.

Of course the rf signal that drives the laser also apears on the signal
despite this being further away and shelded also. Although I havnt however
fuly soldered the sheilds in place yet as then it would be hard to make
changes. it is however only noticable when the gain is turned up max and the
detector totaly blanked out, also as i think i said before stray reflections
albeit invisible were also an issue at one point.

Colin =^.^=

 

[John Larkin]

On Fri, 24 Sep 2004 18:56:21 +0200, Rene Tschaggelar <none@none.net>
wrote:

Phil Hobbs wrote:

No, it's 1 mW peak--I'm just sticking a single mode fibre behind a ND
2.5 filter, right in the unfocused beam. The actual laser peak laser
power is more like 10 MW. Fibre optics works great when your optical
pulses are only a quarter of an inch long.

My rep rate is only 20 Hz, and the flashlamp jitter is probably hundreds
of nanoseconds, so I have to synchronize on each pulse separately.

The MAR-3 has a low, resistive input impedance, and the photocurrent
pulse is unipolar and has a very low duty cycle, so the net effect is
very nearly identical to capacitive coupling (within 1 part in 10**10).
Adding additional components on the input would just have added stray
capacitive loading without changing anything.

Interesting that you get some signal at all from 1mWpk.
And with a straight input to a MAR3

Rene

1 mW is a huge optical signal! It will get you 0.5 mA or better from
most any pin diode.

John