Driver to drive?

On Mon, 28 Sep 2009 09:36:18 -0700, Rich Grise <richgrise@example.net>
wrote:

On Fri, 25 Sep 2009 17:23:09 -0700, John Larkin wrote:
On Fri, 25 Sep 2009 16:58:08 -0700 (PDT), Too_Many_Tools

If you were going to equipt a home test bench today for both analog
and digital work, what test equipment would you choose and why?

TMT

Something like this:

ftp://jjlarkin.lmi.net/DSC01371.JPG

Wow! Paper towels _and_ Kimwipes!

Lah-di-dah!
Click to expand...
And single-ended real wood Q-tips. And *three* different sizes of
solder-wick! Eat your heart out.

BTW, do you buy the "select-a-size" towels? :)

Cheers!
Rich
Click to expand...
Mais oui.

John
 
On Mon, 28 Sep 2009 09:32:28 -0700, Rich Grise <richgrise@example.net>
wrote:

On Sat, 26 Sep 2009 07:50:43 -0700, John Larkin wrote:
On Sat, 26 Sep 2009 18:24:05 +1000, "David L. Jones"

A PC based digital logic analyser. Combined LA's in digital oscilloscopes
can be handy, but USB ones offer better bang-per-buck.

I've never used a logic analyzer. A digital scope can spot the obvious
glitch-type errors, and all a LA does after that is force you to do
the thinking you should have done in the first place. They take so
much time to connect and use, it's a lot quicker and easier to just
think.


One can be indispensable if you're trouble-shooting somebody _else_'s
design. And if I'm getting paid by the hour, what do I care how long it
takes to hook up? ;-)

But I'm only a tech, what do I know? ;-)

When I was interviewing for the video game/pinball/jukebox repair job,
I told the guy, "Well, when a game gets fixed, it has to be tested, and
where else would I be able to play games for free? ;-)"

I got the job. :)

Cheers!
Rich
Click to expand...
If you ever want a change of scene, I have a friend who
buys/refurbs/sells slot machines in Los Vegas, several thousand a
month. He made a fortune in Silicon valley and moved to Nevada for tax
reasons, got bored, started the slot thing, and is making another
fortune. Some people are like that.

John
 
On Mon, 28 Sep 2009 11:34:54 -0700, John Larkin wrote:
On Mon, 28 Sep 2009 09:32:28 -0700, Rich Grise <richgrise@example.net
On Sat, 26 Sep 2009 07:50:43 -0700, John Larkin wrote:
On Sat, 26 Sep 2009 18:24:05 +1000, "David L. Jones"

A PC based digital logic analyser. Combined LA's in digital oscilloscopes
can be handy, but USB ones offer better bang-per-buck.

I've never used a logic analyzer. A digital scope can spot the obvious
glitch-type errors, and all a LA does after that is force you to do
the thinking you should have done in the first place. They take so
much time to connect and use, it's a lot quicker and easier to just
think.

One can be indispensable if you're trouble-shooting somebody _else_'s
design. And if I'm getting paid by the hour, what do I care how long it
takes to hook up? ;-)

But I'm only a tech, what do I know? ;-)

When I was interviewing for the video game/pinball/jukebox repair job,
I told the guy, "Well, when a game gets fixed, it has to be tested, and
where else would I be able to play games for free? ;-)"

I got the job. :)

If you ever want a change of scene, I have a friend who
buys/refurbs/sells slot machines in Los Vegas, several thousand a
month. He made a fortune in Silicon valley and moved to Nevada for tax
reasons, got bored, started the slot thing, and is making another
fortune. Some people are like that.

Would he relocate me (~$50.00 on Greyhound, plus maybe a couple hundred
Click to expand...
bucks traveling money (food, booze, cigs)) and put me up until I make
enough to pay my own rent?

Thanks,
Rich
 
On Mon, 28 Sep 2009 10:51:21 -0700 (PDT), Bill Sloman
<bill.sloman@ieee.org> wrote:

On Sep 28, 5:26 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Mon, 28 Sep 2009 04:35:22 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 28, 2:23 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 16:37:43 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 9:24 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 11:44:52 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 6:29 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 03:55:25 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 2:02 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 15:54:37 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 26, 4:52 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 00:27:41 -0400, "Martin Riddle"

martin_...@verizon.net> wrote:
http://blog.heritage.org/2009/06/29/an-inconvenient-voice-dr-alan-car...

Cheers

How would a lawyer and community organizer know the real truth about
anything?

Listen to the best available advice? Dubbya was exposed to the same
quality of advice, but chose to ignore advice that he found
inconvenient or distasteful.

You have shown signs of a similar problem.

Idiot. You know nothing about my life except that I have a job and
design good electronics. I know nothing about your life except that
you don't, and you don't.

There you go. You know that I haven't got a job because I've told you.
You know very little about the electronics I've designed because
you've seen very little of it, but despite this you are willing to
claim that I don't design good electronics.

Post something and show us. Something not 20 years old.

Since I'm complaining that you don't draw logical conclusions from the
evidence available, it would be waste of time for me to present you
with evidence for a proposition that obviously wouldn't take your
fancy.

Convenient evasion. You'd rather talk about climate and economics,
untestable studies where you can cite other peoples' "peer reviewed"
work as evidence of your intelligence and fuel for insults. How
dreary.

And what's wrong with twenty year old circuits? You seem to boast
about developing the same kind of stuff I was doing thirty years ago -
since then the  bleeding edge of technology has moved on a bit so your
stuff goes a bit faster, but you don't - for instance - claim to be
using the sort of auto-calibration tricks that we were using back then

You conclude that we don't use autocal from the fact that I don't talk
much about autocal?

See any trimpots?

ftp://jjlarkin.lmi.net/DSC01786.JPG

The SO-8 under the eprom socket is a serial eeprom. It holds the
serial number, dash number, and the cal table, full of polynomials and
tempco factors and such. All this sort of stuff is obvious and
mandatory these days, not to mention tedious, so there's not a lot to
say about it.

That's not auto calibration, that's just replacing trim pots and screw
drivers with digital pots

none of them, either

I was using "digital pot" in the broad sense of a device with a
programmable impedance, in the same sense that "trim pots" in this
kind of context has to include trimming capacitors and moveable slugs
in inductors.

Don't use them on this design, rarely ever. Most cals are pure
digital, in the FPGA. Some analog offset type things use dacs. The
only "variable impedance" things we commonly use are varicaps.

I've been searching for a good wideband (true DC to a GHz or so)
programmable attenuator, but nothing wonderful so far.

and an eprom programmer.

The eprom holds the code, same for all units. The cal factors and
serial number and options mask are in serial eeprom.

Autocalibration is
where the circuit monitors its own off-sets and delays and reprograms
the equivalent of your serial eprom every few minutes (or whenever).

Genuine calibration has to be tracable to - in the USA - NIST primary
standards.

So what. This sin't the kind of calibration that I was talking about.

No device can calibrate itself.

Why not? If it were to include a primary standard it could certainly
do just that.

You've suggested that before. How do I add primary standards to a
20-square-inch board that sells for a few K$? Hell, I could sell that
part alone for $100K.

You are changing your claim to "no cheap device can calibrate itself"?
Click to expand...
My claim is still that building primary standards into measuring
instruments is insane. And given any reasonable size restrictions,
impossible.

No sensible customer would trust any calibration that wasn't tracible
to a National standard. If we claimed we had primary standards on
board, they would think we're crazy.

If you can build a small box that has primary voltage, frequency,
capacitance, temperature, optical power, and resistance standards
inside, why don't you?


Few devices can afford to
stop working whenever they feel like and re-zero or linearize
themselves; customers wouldn't like that, and we *do* have customers.

This obviously depends on application, and on how fast the re-
calibration can be done. I once put togheter a scheme where we should
have been able to measure all the 128 fine time delays we could
generate within one millisecond

One millisecond timeout is planty enough to make a product useless, or
dangerous. One nanosecond could, ditto.

This entirely depends on the application. Your stuff for the laser
ignition facility isn't going to busy 100% of the time, and a one
millisecond timeout immediately after a laser shot wouldn't make the
product either dangerous or useless.
Click to expand...
Various parts of the system run continuously between shots,
self-calibrating the adaptive optics and such. We got an award from
NIF for our timing system - a handsome laser-engraved wooden thing -
so who the hell are you to tell us how we should have done it?


Some things can get done quietly in background, like tempco tweaks,
but the intervention must not compromise signal quality. It's better
to design stuff that doesn't drift much, which isn't real hard these
days.

What's the non-temperature-sensitive equivalent of the MC100E195

http://www.onsemi.com/pub_link/Collateral/MC10E195-D.PDF

The Micrel parts are much better, but still but have TCs that vary
with programmed delay. But the compensations have to be non-intrusive
on continuous signal processing... no timeouts, no tap switching
allowed.

For some applications.
Click to expand...
Like most real ones. I won't design a product that is fatally flawed
for some fraction of my customers.


For the record, I did the concept, the architecture, the target specs,
schematic, the firmware, the cal procedure/firmware/PC software, and
the manual myself. I worked with two other people on the FPGA and the
pcb layout. One of my resolves in life is to never have to drive the
ghastly Xilinx software myself. No cuts, no jumpers, no breadboard, no
prototype: rev A works.

Sure. I've done all of that, and laid out a one or two printed circuit
boards as well. Am I supposed to be impressed?

I myself hate writing manuals, and know at least one guy who is
brilliant at it. At least he was brilliant at it when I knew him in
Cambridge, when I managed to get him the job of writing the manual
that my boss wanted me to write.

http://www.interface.co.uk/

I haven't written any software worth talking about since 1976, though
I've tinkered with other people's code once or twice since then, but I
don't have any problem with assembler and programming programmable
logic devices.

This arbitrary waveform generator also has BIST - note the relays -
the coding of which was pretty tedious. Hardly cocktail party
conversation.

Relays? Couldn't you use some kind of analog switch? Relays do have
their virtues, but they are big.

These aren't very big. Their on/off ratio can't be touched by any
semiconductor I know of. Zero failures so far, too.

The on-off ratios can be very good. The life-time is finite, but 10^7
operations is often enough, and there ae always mercury wetted reed
relays if you need 10^8.

Mercury is illegal these days, and DPDT mercury relays were never
plentiful. Many were position sensitive. The little telecom relays are
small, cheap, and very reliable. The latching types have unmeasurable
thermal offsets; reeds are rotten thermally.

Non-position sensitive mercury wetted reed relays have been offered
for sale from time to time, but every time I tried to buy one they'd
been withdrawn from the market. I don't believe that they can be made
reliably.

Mercury-wetted reeds are hermitically sealed, and the mercury is no
more dangerous that the mercury in a clinical thermometer - less so,
in fact because the reed is less at risk of being broken.
Click to expand...
Tell that to the ROHS folks.


I designed this dc/dc inverter for this project

ftp://jjlarkin.lmi.net/Inverter.jpg

which was fun because it's "real circuit design", not just plugging in
a commercial regulator chip. I did breadboard this bit.

Pretty crude. You use the +5V rail plus the Vbe of Q1 as your voltage
reference.

It's not crude, it's elegant.

A 5V rail is never an elegant voltage reference, and throwing in an
uncompensated Vbe doesn't improve it.

How do you get to make statements like that?

How come you can't argue with it?

Max duty cycle is controlled by design,
it's dead stable, and load regulation and efficiency are excellent.
It's fine for its purpose, which is powering opamps.

Show us a switcher you've designed, and we'll grade its
sophistication.

That you think that the circuit you posted is "elegant" confirms my
comments about the self-gratifying nature of your "judgement". Your
conclusions about the sophistication of any circuit I might produce
are a little too predictable.

Show us.

I'll skip the bother of doing that and accept the fact that you would
find it to be rubbish.
Click to expand...
I bet we would.

John
 
Jim Thompson wrote:
Latest version of the board game, Monopoly...

http://www.analog-innovations.com/SED/Bamopoly.jpg

...Jim Thompson
Click to expand...
Really, the republicans have only themselves to blame.
They screwed up big time - so they were voted out.

Happens all the time.

Here, in the UK, the labour party will be thrown out and replaced by conservatives.

Virtually all politicians are thieving incompetent bastards - and we all have to pay for their mistakes and excesses.
 
On Sep 28, 4:44 pm, John Fields <jfie...@austininstruments.com> wrote:
On Sun, 27 Sep 2009 16:41:23 -0700 (PDT),Bill Sloman





bill.slo...@ieee.org> wrote:
On Sep 27, 11:23 pm, krw <k...@att.bizzzzzzzzzzz> wrote:
On Sun, 27 Sep 2009 12:24:39 -0700, John Larkin

jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 11:44:52 -0700 (PDT),Bill Sloman
bill.slo...@ieee.org> wrote:

On Sep 27, 6:29 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 03:55:25 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 2:02 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 15:54:37 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 26, 4:52 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 00:27:41 -0400, "Martin Riddle"

martin_...@verizon.net> wrote:
http://blog.heritage.org/2009/06/29/an-inconvenient-voice-dr-alan-car...

Cheers

How would a lawyer and community organizer know the real truth about
anything?

Listen to the best available advice? Dubbya was exposed to the same
quality of advice, but chose to ignore advice that he found
inconvenient or distasteful.

You have shown signs of a similar problem.

Idiot. You know nothing about my life except that I have a job and
design good electronics. I know nothing about your life except that
you don't, and you don't.

There you go. You know that I haven't got a job because I've told you.
You know very little about the electronics I've designed because
you've seen very little of it, but despite this you are willing to
claim that I don't design good electronics.

Post something and show us. Something not 20 years old.

Since I'm complaining that you don't draw logical conclusions from the
evidence available, it would be waste of time for me to present you
with evidence for a proposition that obviously wouldn't take your
fancy.

Convenient evasion. You'd rather talk about climate and economics,
untestable studies where you can cite other peoples' "peer reviewed"
work as evidence of your intelligence and fuel for insults. How
dreary.

And what's wrong with twenty year old circuits? You seem to boast
about developing the same kind of stuff I was doing thirty years ago -
since then the  bleeding edge of technology has moved on a bit so your
stuff goes a bit faster, but you don't - for instance - claim to be
using the sort of auto-calibration tricks that we were using back then

You conclude that we don't use autocal from the fact that I don't talk
much about autocal?

In fact, you have talked some about it.  As usual, Slowman lies.

As usual, krw doesn't know what he is talking about. If I were to ask
him to produce evidence to support his claim he'd come up as empty as
he always does.

---
Instead of evasion and bullshit, why don't you just post something
clever you've designed, or STFU?
Click to expand...
You are asking for the impossible - nothing that I'd describe as
clever would be simple enough for you to understand.

--
Bill Sloman, Nijmegen
 
On Sep 28, 5:26 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Mon, 28 Sep 2009 04:35:22 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 28, 2:23 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 16:37:43 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 9:24 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 11:44:52 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 6:29 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 03:55:25 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 2:02 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 15:54:37 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 26, 4:52 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 00:27:41 -0400, "Martin Riddle"

martin_...@verizon.net> wrote:
http://blog.heritage.org/2009/06/29/an-inconvenient-voice-dr-alan-car...

Cheers

How would a lawyer and community organizer know the real truth about
anything?

Listen to the best available advice? Dubbya was exposed to the same
quality of advice, but chose to ignore advice that he found
inconvenient or distasteful.

You have shown signs of a similar problem.

Idiot. You know nothing about my life except that I have a job and
design good electronics. I know nothing about your life except that
you don't, and you don't.

There you go. You know that I haven't got a job because I've told you.
You know very little about the electronics I've designed because
you've seen very little of it, but despite this you are willing to
claim that I don't design good electronics.

Post something and show us. Something not 20 years old.

Since I'm complaining that you don't draw logical conclusions from the
evidence available, it would be waste of time for me to present you
with evidence for a proposition that obviously wouldn't take your
fancy.

Convenient evasion. You'd rather talk about climate and economics,
untestable studies where you can cite other peoples' "peer reviewed"
work as evidence of your intelligence and fuel for insults. How
dreary.

And what's wrong with twenty year old circuits? You seem to boast
about developing the same kind of stuff I was doing thirty years ago -
since then the  bleeding edge of technology has moved on a bit so your
stuff goes a bit faster, but you don't - for instance - claim to be
using the sort of auto-calibration tricks that we were using back then

You conclude that we don't use autocal from the fact that I don't talk
much about autocal?

See any trimpots?

ftp://jjlarkin.lmi.net/DSC01786.JPG

The SO-8 under the eprom socket is a serial eeprom. It holds the
serial number, dash number, and the cal table, full of polynomials and
tempco factors and such. All this sort of stuff is obvious and
mandatory these days, not to mention tedious, so there's not a lot to
say about it.

That's not auto calibration, that's just replacing trim pots and screw
drivers with digital pots

none of them, either

I was using "digital pot" in the broad sense of a device with a
programmable impedance, in the same sense that "trim pots" in this
kind of context has to include trimming capacitors and moveable slugs
in inductors.

Don't use them on this design, rarely ever. Most cals are pure
digital, in the FPGA. Some analog offset type things use dacs. The
only "variable impedance" things we commonly use are varicaps.

I've been searching for a good wideband (true DC to a GHz or so)
programmable attenuator, but nothing wonderful so far.

and an eprom programmer.

The eprom holds the code, same for all units. The cal factors and
serial number and options mask are in serial eeprom.

Autocalibration is
where the circuit monitors its own off-sets and delays and reprograms
the equivalent of your serial eprom every few minutes (or whenever).

Genuine calibration has to be tracable to - in the USA - NIST primary
standards.

So what. This sin't the kind of calibration that I was talking about.

No device can calibrate itself.

Why not? If it were to include a primary standard it could certainly
do just that.

You've suggested that before. How do I add primary standards to a
20-square-inch board that sells for a few K$? Hell, I could sell that
part alone for $100K.
Click to expand...
You are changing your claim to "no cheap device can calibrate itself"?

Few devices can afford to
stop working whenever they feel like and re-zero or linearize
themselves; customers wouldn't like that, and we *do* have customers.

This obviously depends on application, and on how fast the re-
calibration can be done. I once put togheter a scheme where we should
have been able to measure all the 128 fine time delays we could
generate within one millisecond

One millisecond timeout is planty enough to make a product useless, or
dangerous. One nanosecond could, ditto.
Click to expand...
This entirely depends on the application. Your stuff for the laser
ignition facility isn't going to busy 100% of the time, and a one
millisecond timeout immediately after a laser shot wouldn't make the
product either dangerous or useless.

Some things can get done quietly in background, like tempco tweaks,
but the intervention must not compromise signal quality. It's better
to design stuff that doesn't drift much, which isn't real hard these
days.

What's the non-temperature-sensitive equivalent of the MC100E195

http://www.onsemi.com/pub_link/Collateral/MC10E195-D.PDF

The Micrel parts are much better, but still but have TCs that vary
with programmed delay. But the compensations have to be non-intrusive
on continuous signal processing... no timeouts, no tap switching
allowed.
Click to expand...
For some applications.

For the record, I did the concept, the architecture, the target specs,
schematic, the firmware, the cal procedure/firmware/PC software, and
the manual myself. I worked with two other people on the FPGA and the
pcb layout. One of my resolves in life is to never have to drive the
ghastly Xilinx software myself. No cuts, no jumpers, no breadboard, no
prototype: rev A works.

Sure. I've done all of that, and laid out a one or two printed circuit
boards as well. Am I supposed to be impressed?

I myself hate writing manuals, and know at least one guy who is
brilliant at it. At least he was brilliant at it when I knew him in
Cambridge, when I managed to get him the job of writing the manual
that my boss wanted me to write.

http://www.interface.co.uk/

I haven't written any software worth talking about since 1976, though
I've tinkered with other people's code once or twice since then, but I
don't have any problem with assembler and programming programmable
logic devices.

This arbitrary waveform generator also has BIST - note the relays -
the coding of which was pretty tedious. Hardly cocktail party
conversation.

Relays? Couldn't you use some kind of analog switch? Relays do have
their virtues, but they are big.

These aren't very big. Their on/off ratio can't be touched by any
semiconductor I know of. Zero failures so far, too.

The on-off ratios can be very good. The life-time is finite, but 10^7
operations is often enough, and there ae always mercury wetted reed
relays if you need 10^8.

Mercury is illegal these days, and DPDT mercury relays were never
plentiful. Many were position sensitive. The little telecom relays are
small, cheap, and very reliable. The latching types have unmeasurable
thermal offsets; reeds are rotten thermally.
Click to expand...
Non-position sensitive mercury wetted reed relays have been offered
for sale from time to time, but every time I tried to buy one they'd
been withdrawn from the market. I don't believe that they can be made
reliably.

Mercury-wetted reeds are hermitically sealed, and the mercury is no
more dangerous that the mercury in a clinical thermometer - less so,
in fact because the reed is less at risk of being broken.

I designed this dc/dc inverter for this project

ftp://jjlarkin.lmi.net/Inverter.jpg

which was fun because it's "real circuit design", not just plugging in
a commercial regulator chip. I did breadboard this bit.

Pretty crude. You use the +5V rail plus the Vbe of Q1 as your voltage
reference.

It's not crude, it's elegant.

A 5V rail is never an elegant voltage reference, and throwing in an
uncompensated Vbe doesn't improve it.

How do you get to make statements like that?
Click to expand...
How come you can't argue with it?

Max duty cycle is controlled by design,
it's dead stable, and load regulation and efficiency are excellent.
It's fine for its purpose, which is powering opamps.

Show us a switcher you've designed, and we'll grade its
sophistication.

That you think that the circuit you posted is "elegant" confirms my
comments about the self-gratifying nature of your "judgement". Your
conclusions about the sophistication of any circuit I might produce
are a little too predictable.

Show us.
Click to expand...
I'll skip the bother of doing that and accept the fact that you would
find it to be rubbish.

You could check out the switch-mode curent drive that I published in
Measurment Science and Technology back in 1996 - Meas. Sci. Technol. 7
(1996) 1653–1664  "A microcontroller-based driver to stabilize the
temperature of an optical stage to within 1 mK in the range 4–38  C,
using a Peltier heat pump
and a thermistor sensor" by A W Slomany, Paul Buggs, James Molloy and
Douglas Stewart.

Post it somewhere.
Click to expand...
It's available at a university library near you, and the UK Institute
of Physics will sell you the .pdf file; they own the copyright so you
won't be able to post it on the web.

The switched mode driver than can send up to 3A through the Peltier
junction has an element of sophistication.

Gosh. 3 amps.
Click to expand...
That was as much current as could be usefully be driven through the
Peltier junction we ended up using. Are you confusing size with
sophisitcation?

What made it necessary to "design" this rather than finding a
commercial regulator chip?

Positive-to-negative inverters are rare, especially at 12 volts and
close to an amp. And I did it because I enjoyed it.

A rather perverse pleasure, considering the result.

Do I have to give all the money back?
Click to expand...
That's between you and your customers, but I hope you didn't have some
kind of phrase like "insanely good" anywhere in the specification.

--
Bill Sloman, Nijmegen
 
On Mon, 28 Sep 2009 10:27:45 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 18:01:12 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 26 Sep 2009 17:26:03 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


Corian. Great stuff.


Not for electronic PCB work, dumbfuck.

Suitable for HV work, but NOT for ANY of the kind of stuff you claim to
make.

Your grasp of the things that matter always seems to ignore those
things that you were never smart enough to grasp the depth of. How
convenient for you. How sad for your customers.

You probably do not even know what the term 'infant mortality' means.

We see no evidence of a bathtub curve these days. Field failure rates
are low, far below MIL-217 or Bellcore calcs, and failures seem to be
pretty uniform over time. Most failures are because of some sort of
abuse.

John


aka Zero observance of ESD precautions.
Click to expand...
 
On Mon, 28 Sep 2009 13:00:42 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

Rich Grise wrote:

On Fri, 25 Sep 2009 17:23:09 -0700, John Larkin wrote:

On Fri, 25 Sep 2009 16:58:08 -0700 (PDT), Too_Many_Tools


If you were going to equipt a home test bench today for both analog
and digital work, what test equipment would you choose and why?

TMT

Something like this:

ftp://jjlarkin.lmi.net/DSC01371.JPG


Wow! Paper towels _and_ Kimwipes!

Lah-di-dah!

BTW, do you buy the "select-a-size" towels? :)

Cheers!
Rich

Now I don't feel so bad that I got a 47x boom scope for the
bench!..


I certainly don't feel so bad about having a 3/16" thick, carbon
Click to expand...
impregnated throughout the medium, absolute proper dissipation
resistance, 30"x 25" ESD mat with a grounding node and cord on it sitting
on my bench. Also, every time a company I work for uses a panel of it, I
grab whatever scraps they do not want.

It is the same way we concerned electrical engineering types used to
collect the carbon rich dissipative foam so we could move chips back and
forth around the lab.

A proper electronic workstation is not just about what your gear pile
has in it. The furniture must be properly outfitted, and that is first
and foremost rule.

Same type of dopes that would sit on a pool table, or shoot at balls
other than the cue ball.

The first rule is respect the equipment, and that is always the first
rule that gets thrown out.

Just not by me.
 
On Mon, 28 Sep 2009 11:50:40 -0700, Rich Grise <richgrise@example.net>
wrote:

On Mon, 28 Sep 2009 11:34:54 -0700, John Larkin wrote:
On Mon, 28 Sep 2009 09:32:28 -0700, Rich Grise <richgrise@example.net
On Sat, 26 Sep 2009 07:50:43 -0700, John Larkin wrote:
On Sat, 26 Sep 2009 18:24:05 +1000, "David L. Jones"

A PC based digital logic analyser. Combined LA's in digital oscilloscopes
can be handy, but USB ones offer better bang-per-buck.

I've never used a logic analyzer. A digital scope can spot the obvious
glitch-type errors, and all a LA does after that is force you to do
the thinking you should have done in the first place. They take so
much time to connect and use, it's a lot quicker and easier to just
think.

One can be indispensable if you're trouble-shooting somebody _else_'s
design. And if I'm getting paid by the hour, what do I care how long it
takes to hook up? ;-)

But I'm only a tech, what do I know? ;-)

When I was interviewing for the video game/pinball/jukebox repair job,
I told the guy, "Well, when a game gets fixed, it has to be tested, and
where else would I be able to play games for free? ;-)"

I got the job. :)

If you ever want a change of scene, I have a friend who
buys/refurbs/sells slot machines in Los Vegas, several thousand a
month. He made a fortune in Silicon valley and moved to Nevada for tax
reasons, got bored, started the slot thing, and is making another
fortune. Some people are like that.

Would he relocate me (~$50.00 on Greyhound, plus maybe a couple hundred
bucks traveling money (food, booze, cigs)) and put me up until I make
enough to pay my own rent?

Thanks,
Rich
Click to expand...

Florida that bad, eh?
 
On Mon, 28 Sep 2009 13:27:01 -0700, Archimedes' Lever
<OneBigLever@InfiniteSeries.Org> wrote:

On Mon, 28 Sep 2009 10:27:45 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 18:01:12 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 26 Sep 2009 17:26:03 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


Corian. Great stuff.


Not for electronic PCB work, dumbfuck.

Suitable for HV work, but NOT for ANY of the kind of stuff you claim to
make.

Your grasp of the things that matter always seems to ignore those
things that you were never smart enough to grasp the depth of. How
convenient for you. How sad for your customers.

You probably do not even know what the term 'infant mortality' means.

We see no evidence of a bathtub curve these days. Field failure rates
are low, far below MIL-217 or Bellcore calcs, and failures seem to be
pretty uniform over time. Most failures are because of some sort of
abuse.

John


aka Zero observance of ESD precautions.
Click to expand...
My production people use proper ESD procedures on all shippable gear.
But we sell a lot of VME modules, which are raw PC boards with front
panels, and a customer can handle all the exposed stuff any way he
wants.

See... no enclosure...

http://www.highlandtechnology.com/DSS/V420DS.html

But as noted, our field failure rates are well below industry
standards, roughly 5:1 below Bellcore calcs. I think MTBF is dominated
by design, not parts reliability. Most parts are pretty well ESD
hardened these days anyhow, with a few known exceptions. I don't think
I've ever zapped a part at my office workbench.

And I'm not sure I believe in "latent" ESD damage.

Besides, I've long ago acquired the instincts to keep myself
un-charged and things equipotential. And humidity is usually so high
here that static zaps are rare. And I don't build or test production
stuff.

John
 
On Mon, 28 Sep 2009 20:21:21 +0100, richard wrote:
Jim Thompson wrote:
Latest version of the board game, Monopoly...

http://www.analog-innovations.com/SED/Bamopoly.jpg

Really, the republicans have only themselves to blame.
They screwed up big time - so they were voted out.
Click to expand...
Well, it's pretty obvious Cheney/Bush wanted to dump the worst possible
mess they could into Obama's lap.

And what's Obama's first act in office? To do more of the same, but worse!

You _could_ look it up, but I doubt if you will.

Nine months in office and still blaming Bush? That's just lame.

Thanks,
Rich
 
On Mon, 28 Sep 2009 16:05:00 -0700 (PDT), Bill Sloman
<bill.sloman@ieee.org> wrote:

On Sep 28, 9:05 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Mon, 28 Sep 2009 10:51:21 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 28, 5:26 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Mon, 28 Sep 2009 04:35:22 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 28, 2:23 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 16:37:43 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 9:24 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 11:44:52 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 6:29 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 27 Sep 2009 03:55:25 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 27, 2:02 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 15:54:37 -0700 (PDT),Bill Sloman

bill.slo...@ieee.org> wrote:
On Sep 26, 4:52 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 00:27:41 -0400, "Martin Riddle"

martin_...@verizon.net> wrote:

snip

Genuine calibration has to be tracable to - in the USA - NIST primary
standards.

So what. This sin't the kind of calibration that I was talking about.

No device can calibrate itself.

Why not? If it were to include a primary standard it could certainly
do just that.

You've suggested that before. How do I add primary standards to a
20-square-inch board that sells for a few K$? Hell, I could sell that
part alone for $100K.

You are changing your claim to "no cheap device can calibrate itself"?

My claim is still that building primary standards into measuring
instruments is insane. And given any reasonable size restrictions,
impossible.

So you are changing your claim - again - to "no small device can
calibrate itself"?
Click to expand...
What have you done, married John Fields?

Play with words all you like. I design electrronics.

John
 
On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:


John Larkin wrote:

There's the slideback technique: drive a comparator with RF on one
side, DC feedback on the other. Tease the DC appropriately.

I once made a slideback sampling oscilloscope, using tunnel diodes, as
my EE senior project. I won an award and had to attend a dreadful IEEE
chapter banquet and repeat it to a bunch of old-fart power engineers
who didn't understand a word I said. I described the slideback
sampling scope in this ng some years back and a certain party loved
the idea so much he later decided that he'd invented it himself.


http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html

TDs are insanely expensive nowadays, ballpark $100. I used to get them
for a couple bucks from Allied. The fabrication process is insane, and
nobody ever modernized it.

There are some more modern planar germanium back diodes, essentially
low Ip tunnel diodes, but they're RF detectors, useless for switching.
Pity, I used to like tunnel diodes.

http://aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf

John


Try PiN diodes then.

For what? Certainly not switching, amplifying, oscillating, detection,
or mixing.
Click to expand...
---
Re. switching, From:

http://en.wikipedia.org/wiki/PIN_diode

"Under zero or reverse bias, a PIN diode has a low capacitance. The low
capacitance will not pass much of an RF signal. Under a forward bias of
1 mA, a typical PIN diode will have an RF resistance of about 1 ohm,
making it a good RF conductor. Consequently, the PIN diode makes a good
RF switch."
---

There was a single-TD circuit that was an RF amp, a local oscillator,
a mixer, and an IF amp. One TD and a couple of passives would make an
FM transmitter.
Click to expand...
---
Got a link?
---

The beefier td's would make a voltage step with a 22 picosecond rise
time... in 1964.
Click to expand...
---
Got a link?
 
On Mon, 28 Sep 2009 15:30:13 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Mon, 28 Sep 2009 13:27:01 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Mon, 28 Sep 2009 10:27:45 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 18:01:12 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 26 Sep 2009 17:26:03 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


Corian. Great stuff.


Not for electronic PCB work, dumbfuck.

Suitable for HV work, but NOT for ANY of the kind of stuff you claim to
make.

Your grasp of the things that matter always seems to ignore those
things that you were never smart enough to grasp the depth of. How
convenient for you. How sad for your customers.

You probably do not even know what the term 'infant mortality' means.

We see no evidence of a bathtub curve these days. Field failure rates
are low, far below MIL-217 or Bellcore calcs, and failures seem to be
pretty uniform over time. Most failures are because of some sort of
abuse.

John


aka Zero observance of ESD precautions.

My production people use proper ESD procedures on all shippable gear.
But we sell a lot of VME modules, which are raw PC boards with front
panels, and a customer can handle all the exposed stuff any way he
wants.
Click to expand...
No, one cannot!

See... no enclosure...

http://www.highlandtechnology.com/DSS/V420DS.html
Click to expand...
So what. Also SEE the ESD bag it came it, and see the precautions the
manual for it no doubt declares.

Your dopeyness factor just bumped up an order of magnitude.

But as noted, our field failure rates are well below industry
standards,
Click to expand...
So what? If any of it ever gets used in a mission critical situation,
you should not be taking the chance to begin with or at all, nor should
you attempt to diminish the dangers of electrostatic fields and charged
bodies around circuit card assemblies.

roughly 5:1 below Bellcore calcs.
Click to expand...
Okie dokie.

I think MTBF is dominated
by design, not parts reliability.
Click to expand...
Scary.

Most parts are pretty well ESD
hardened these days anyhow,
Click to expand...
You ain't real bright sometimes, John.

with a few known exceptions. I don't think
I've ever zapped a part at my office workbench.
Click to expand...
I do not think you would even know. There doesn't have to be a
noticeable 'zap' as you call it. as little as a 20 volt charge 'on' you
without a smock would do it. And yes, without a smock, you will carry a
charge, and build one with every step and arm movement.

And I'm not sure I believe in "latent" ESD damage.
Click to expand...
Which makes one wonder about whether you are aware of just how easy it
is to damage components with ESD.

Here... Try this... I found a pretty good one after a bit of hunting.
Tell me what you think about what this dude knows.

http://virtual.vtt.fi/virtual/staha/staha/sem5-02/smallwood_jeremy_electrostaticsolutionsltd1.pdf
Besides, I've long ago acquired the instincts to keep myself
un-charged and things equipotential.
Click to expand...
Very well put description of a good regimen for one to keep. You do
not appear to keep it, however. Easy test... Smock? Strap? MAT?

I always "touch the mat" when I get to a bench. Then, I "hook-up" for
low voltage stuff. Ideally the ionizing evacuation fan for soldering, or
(and) even an overhead cascade source at the bench. One should also
always have a smock on, because it keep fields inside you, the charge
receptacle.

And humidity is usually so high
here that static zaps are rare.
Click to expand...
We are at like 40% to 65%, and again, one does NOT have to "see" OR
"hear" a "zap" for there to have been an exchange of electrons from a
charged body into a circuit element.

There is a point at which the humidity is too high, so our entire lab
is controlled, though it has been running a little toward the high end
lately.

And I don't build or test production
stuff.
Click to expand...
Oh... I thought that was your home bench. I wondered why you wouldn't
want to also take every precaution at home as well.

That's at work? Wow.
 
John Fields wrote:
On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:

John Larkin wrote:
There's the slideback technique: drive a comparator with RF on one
side, DC feedback on the other. Tease the DC appropriately.

I once made a slideback sampling oscilloscope, using tunnel diodes, as
my EE senior project. I won an award and had to attend a dreadful IEEE
chapter banquet and repeat it to a bunch of old-fart power engineers
who didn't understand a word I said. I described the slideback
sampling scope in this ng some years back and a certain party loved
the idea so much he later decided that he'd invented it himself.

http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html
TDs are insanely expensive nowadays, ballpark $100. I used to get them
for a couple bucks from Allied. The fabrication process is insane, and
nobody ever modernized it.

There are some more modern planar germanium back diodes, essentially
low Ip tunnel diodes, but they're RF detectors, useless for switching.
Pity, I used to like tunnel diodes.

http://aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf

John

Try PiN diodes then.
For what? Certainly not switching, amplifying, oscillating, detection,
or mixing.

---
Re. switching, From:

http://en.wikipedia.org/wiki/PIN_diode

"Under zero or reverse bias, a PIN diode has a low capacitance. The low
capacitance will not pass much of an RF signal. Under a forward bias of
1 mA, a typical PIN diode will have an RF resistance of about 1 ohm,
making it a good RF conductor. Consequently, the PIN diode makes a good
RF switch."
---
Click to expand...
Good, but not fast. PIN diodes specialize in having a lot of stored
charge, so that the signal current can be quite a bit larger than the DC
current without causing excessive distortion.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
 
On Mon, 28 Sep 2009 16:48:49 -0700, TralfamadoranJetPilot
<BillyPilgrim@thebigbarattheendoftheuniverse.org> wrote:

On Mon, 28 Sep 2009 15:30:13 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Mon, 28 Sep 2009 13:27:01 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Mon, 28 Sep 2009 10:27:45 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 18:01:12 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 26 Sep 2009 17:26:03 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


Corian. Great stuff.


Not for electronic PCB work, dumbfuck.

Suitable for HV work, but NOT for ANY of the kind of stuff you claim to
make.

Your grasp of the things that matter always seems to ignore those
things that you were never smart enough to grasp the depth of. How
convenient for you. How sad for your customers.

You probably do not even know what the term 'infant mortality' means.

We see no evidence of a bathtub curve these days. Field failure rates
are low, far below MIL-217 or Bellcore calcs, and failures seem to be
pretty uniform over time. Most failures are because of some sort of
abuse.

John


aka Zero observance of ESD precautions.

My production people use proper ESD procedures on all shippable gear.
But we sell a lot of VME modules, which are raw PC boards with front
panels, and a customer can handle all the exposed stuff any way he
wants.

No, one cannot!

See... no enclosure...

http://www.highlandtechnology.com/DSS/V420DS.html

So what. Also SEE the ESD bag it came it, and see the precautions the
manual for it no doubt declares.

Your dopeyness factor just bumped up an order of magnitude.

But as noted, our field failure rates are well below industry
standards,

So what? If any of it ever gets used in a mission critical situation,
you should not be taking the chance to begin with or at all, nor should
you attempt to diminish the dangers of electrostatic fields and charged
bodies around circuit card assemblies.

roughly 5:1 below Bellcore calcs.

Okie dokie.

I think MTBF is dominated
by design, not parts reliability.

Scary.

Most parts are pretty well ESD
hardened these days anyhow,

You ain't real bright sometimes, John.

with a few known exceptions. I don't think
I've ever zapped a part at my office workbench.

I do not think you would even know. There doesn't have to be a
noticeable 'zap' as you call it. as little as a 20 volt charge 'on' you
without a smock would do it. And yes, without a smock, you will carry a
charge, and build one with every step and arm movement.
Click to expand...
I just don't look my rugged, manly best in a smock. And I don't
understand how a smock has any effect on ESD at all. Please explain
how a smock works.

Here... Try this... I found a pretty good one after a bit of hunting.
Tell me what you think about what this dude knows.

http://virtual.vtt.fi/virtual/staha/staha/sem5-02/smallwood_jeremy_electrostaticsolutionsltd1.pdf

Besides, I've long ago acquired the instincts to keep myself
un-charged and things equipotential.

Very well put description of a good regimen for one to keep. You do
not appear to keep it, however. Easy test... Smock? Strap? MAT?

I always "touch the mat" when I get to a bench. Then, I "hook-up" for
low voltage stuff. Ideally the ionizing evacuation fan for soldering, or
(and) even an overhead cascade source at the bench. One should also
always have a smock on, because it keep fields inside you, the charge
receptacle.
Click to expand...
You really have a thing going for smocks. All our boards are assembled
by naked young girls sitting in tubs of tepid water. That seems to
work pretty well.

John
 
On Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

John Fields wrote:
On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:

John Larkin wrote:
There's the slideback technique: drive a comparator with RF on one
side, DC feedback on the other. Tease the DC appropriately.

I once made a slideback sampling oscilloscope, using tunnel diodes, as
my EE senior project. I won an award and had to attend a dreadful IEEE
chapter banquet and repeat it to a bunch of old-fart power engineers
who didn't understand a word I said. I described the slideback
sampling scope in this ng some years back and a certain party loved
the idea so much he later decided that he'd invented it himself.

http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html
TDs are insanely expensive nowadays, ballpark $100. I used to get them
for a couple bucks from Allied. The fabrication process is insane, and
nobody ever modernized it.

There are some more modern planar germanium back diodes, essentially
low Ip tunnel diodes, but they're RF detectors, useless for switching.
Pity, I used to like tunnel diodes.

http://aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf

John

Try PiN diodes then.
For what? Certainly not switching, amplifying, oscillating, detection,
or mixing.

---
Re. switching, From:

http://en.wikipedia.org/wiki/PIN_diode

"Under zero or reverse bias, a PIN diode has a low capacitance. The low
capacitance will not pass much of an RF signal. Under a forward bias of
1 mA, a typical PIN diode will have an RF resistance of about 1 ohm,
making it a good RF conductor. Consequently, the PIN diode makes a good
RF switch."
---

Good, but not fast. PIN diodes specialize in having a lot of stored
charge, so that the signal current can be quite a bit larger than the DC
current without causing excessive distortion.

Cheers

Phil Hobbs
Click to expand...
PINs stop behaving like PINs at low frequencies, too. So they don't
make useful wideband switches.

But I meant active switching when I was referring to a TD. A TD would
*generate* a fast step from an arbitrarily slow drive.

John
 
John Larkin wrote:
On Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

John Fields wrote:
On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:

John Larkin wrote:
There's the slideback technique: drive a comparator with RF on one
side, DC feedback on the other. Tease the DC appropriately.

I once made a slideback sampling oscilloscope, using tunnel diodes, as
my EE senior project. I won an award and had to attend a dreadful IEEE
chapter banquet and repeat it to a bunch of old-fart power engineers
who didn't understand a word I said. I described the slideback
sampling scope in this ng some years back and a certain party loved
the idea so much he later decided that he'd invented it himself.
http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html
TDs are insanely expensive nowadays, ballpark $100. I used to get them
for a couple bucks from Allied. The fabrication process is insane, and
nobody ever modernized it.

There are some more modern planar germanium back diodes, essentially
low Ip tunnel diodes, but they're RF detectors, useless for switching.
Pity, I used to like tunnel diodes.

http://aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf

John
Try PiN diodes then.
For what? Certainly not switching, amplifying, oscillating, detection,
or mixing.
---
Re. switching, From:

http://en.wikipedia.org/wiki/PIN_diode

"Under zero or reverse bias, a PIN diode has a low capacitance. The low
capacitance will not pass much of an RF signal. Under a forward bias of
1 mA, a typical PIN diode will have an RF resistance of about 1 ohm,
making it a good RF conductor. Consequently, the PIN diode makes a good
RF switch."
---
Good, but not fast. PIN diodes specialize in having a lot of stored
charge, so that the signal current can be quite a bit larger than the DC
current without causing excessive distortion.

Cheers

Phil Hobbs

PINs stop behaving like PINs at low frequencies, too. So they don't
make useful wideband switches.

But I meant active switching when I was referring to a TD. A TD would
*generate* a fast step from an arbitrarily slow drive.

John

Sure. TDs are neat. I have a bunch of low-current ones, but they have
Click to expand...
some totally absurd capacitance and so aren't that fast. The really
quick ones have peak currents of something like 50-100 mA. Kind of like
a turbocharged rock crusher.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
 
Is your job application online?

{;-)

Jim


"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:95k2c59k4o6ms80sp3akflfghdeodfeg2d@4ax.com...


All our boards are assembled
by naked young girls sitting in tubs of tepid water. That seems to
work pretty well.

John
Click to expand...
 
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