Driver to drive?

Spehro Pefhany wrote:

On Sat, 02 Oct 2004 19:20:42 -0700, the renowned John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:


One of the old National appnotes does a single-slope ADC at 20 or 24
bits or something.

AN260 January 1981. Like the one described by the OP, it's essentially
a serial single-slope converter, so the capacitor dielectric
absorption doesn't affect the linearity as it does in a dual-slope
converter, and the comparator sees the same dv/dt in the same
direction for reference and unknown measurement.

One interesting thing about this technique is the the differential
linearity is essentially perfect. That can be handy for stuff like
nuclear detector histogramming or electric meters.

John

Doesn't take much leakage across the capacitor or current source to
reduce the linearity at midscale down to the 12-bit level though.
Click to expand...
I might have known you'd spot the flaw!

At low scale or high scale the accuracy is absolutely remarkable. In between
these limits it's only amazing. Still fantasically good for the money (almost
none) though.

Gibbo
 
When I record on a simple cheap cassette
player, however, I get a very spiky waveform, which I guess (thinking
about the physics of it) makes sense. Traces are at
http://www.larwe.com/camctrl.jpg>, sorry for the fuzzy photo.

It doesn't make sense it looks bloody awful.
Click to expand...
It does look like you need WAY less signal to the mic input.
I'd expect a distorted square wave, but not the pulse per edge.

Mic level is something like 20mV IIRC.

--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR
 
Spehro Pefhany wrote:

On Sat, 02 Oct 2004 19:20:42 -0700, the renowned John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:


One of the old National appnotes does a single-slope ADC at 20 or 24
bits or something.

AN260 January 1981. Like the one described by the OP, it's essentially
a serial single-slope converter, so the capacitor dielectric
absorption doesn't affect the linearity as it does in a dual-slope
converter, and the comparator sees the same dv/dt in the same
direction for reference and unknown measurement.

One interesting thing about this technique is the the differential
linearity is essentially perfect. That can be handy for stuff like
nuclear detector histogramming or electric meters.

John

Doesn't take much leakage across the capacitor or current source to
reduce the linearity at midscale down to the 12-bit level though.
Click to expand...
And I'd also like to see any other *serious* contenders for A/D at sensible
accuracy levels for next to *no* outlay.

Gibbo
 
"Of course I know we were attacked by Osama Bin Laden, I know that!"

The president is an idiot, he knows it but hides it well, except once and a
while his insecurity slips out and you get the line I quoted. Think about what
kind of a man would make such a statement, or feel that he needs to make such a
statement?

Only retards would want such a case in a position that requires our best and
brightest. President is a job, while I believe in hiring the handicapped, I
have to draw the line at President, I guess I'm not as PC as the Republicans!

You saw the real GWB in that Debate, I wouldn't hire him to make coffee for me.

Rocky


guess I'm not just as PC as the Republican Party.

Rocky
 
From: John Larkin

'm grateful that he gave us Ronald Reagan, who brought down the Wall
and the USSR
Click to expand...
Rightie Myth Report, this is nearly total BS, and it is a very stupid thing for
anyone to think. Yeah, Reagan stopped shooting people tearing down the wall,
yeap that was him. Reagan started the Unions in the Polish Shipyards. Reagan
fought the Soviets in Afghanistan. Yeap Reagan was actually superman!

Realistic statement is that Reagan's policies and his personal relationship
with Gorbachev were one factor in ending the Soviet Union.

What a bunch of total fools you are! Your cockamamie take on history is just as
bizarre as your take on current reality. Your brains are broke!

Rocky
 
From: Julie julie@nospam.com

Fred -- would you reconsider anything if there were 49 laureates that
endorsed
Bush?
Click to expand...
Where are they, I just love to see smart people that worship and idiot?

Rocky
 
Doesn't take much leakage across the capacitor or current source to
reduce the linearity at midscale down to the 12-bit level though.
Click to expand...
Only 12 bits? Well damn.. :)

I did something like this for a printer.
We needed to read a thermistor, but didn't have an A/D
So, I used the thermistor through a diode to charge a cap, and a fixed
resistor through another diode to discharge the same cap. Cap value factors
out, and the diodes are mounted together, and track nicely. Worked well
enough.

--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR
 
chrisgibbogibson@aol.com (ChrisGibboGibson) wrote:

And I'd also like to see any other *serious* contenders for A/D at sensible
accuracy levels for next to *no* outlay.
Click to expand...
Two precision voltage references, a precision current source, a comparator,
3 way multiplexor and a microprocessor is next to no outlay?

If you use a MOSFET to reset the integrating capacitor to a 'good' 0v then
you can dispense with the 2.5v reference and only require a two way
multiplexor. Slightly better performance and a little closer to *no*
outlay.
 
On Sun, 03 Oct 2004 02:23:08 +0000, ChrisGibboGibson wrote:
[snip]
That was the basis of my post a few days ago regarding a highly accurate CC
generator.

Until I actually tried this (with Fred's CC generator) I couldn't believe the
accuracy that could be got from such a small outlay.

Gibbo
Click to expand...
What exact circuit did you use for the CC generator? You were going to use
a source rather than a sink, weren't you?

--Mac
 
A thermistor typically changes almost 5% per degree C. A 20%-accurate
ADC was probably good enough for limiting the duty cycle of a thermal
printhead. ;-) Sounds like an appropriate design.
Click to expand...
No, and it was way closer than that, but I don't remember the specifics.
It's been a few years.
We also used it to correct the print density for head temperature.

--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR
 
In article <20041002214044.15758.00001353@mb-m13.aol.com>,
ChrisGibboGibson <chrisgibbogibson@aol.com> wrote:
I was bored so.........

Worth trying for fun.
Click to expand...
How about this:

R R ! \
Vin -/\/\/\-------/\/\/\---------------!+ \
! ! ! ------- TooHi to CPU
!!- ---C ---!- /
Ton ----!! --- ! ! /
!!- ! !
! ! REF
GND GND


Loop forever;

TempBit := TooHi;
Ton := TempBit;
Answer := Answer + TempBit - Answer / 65536;
Display Answer;
end;


if the time canstant is long enough, the "answer" value settles to:

65536 * Vin / (2 * Vref)


You can make the main loop of the code do it.
--
--
kensmith@rahul.net forging knowledge
 
On 03 Oct 2004 02:46:45 GMT, chrisgibbogibson@aol.com
(ChrisGibboGibson) wrote:


And I'd also like to see any other *serious* contenders for A/D at sensible
accuracy levels for next to *no* outlay.

Gibbo
Click to expand...

Delta-sigmas are getting awfully cheap, and they are very good. They
have superb linearity and good noise rejection, and integrate well.

I don't recall anyone making a single-slope DVM or anything like that.

John
 
And I'd also like to see any other *serious* contenders for A/D at
sensible accuracy levels for next to *no* outlay.
Click to expand...
AN513 from Microchip, uses pic16c54. could work with most other micros...


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----
 
"ChrisGibboGibson" <chrisgibbogibson@aol.com> wrote in message
news:20041002150752.11054.00001292@mb-m14.aol.com...
We have another product being laucnched in about 2 months time.
[-]

Suggestions ?

Gibbo
Click to expand...
The lads somehow need it explaining to them in laymens simple language. Car
anologies work very well with marketing types. Once they have bought into
the concept on their terms, they can usually come up with surprisingly good
marketing pitch. If they can't then they need sacking :)
'Adaptive-auto-self-tuning-self-aware-intelligent-whatever' usually won't
start their radar scanning, as it's still too technical for them to grasp
and out of respect for you they won't want to admit this.
End result could be some kind of dreary marketing essentially cobbled
together by a commitee.
For the understanding of an idea, marketing people really do appreciate
being treated as morons and giving them lots of day to day unrelated
examples can work wonders. Then let them get on with it.
There is *nothing* a marketing person likes better, than a novel product.
regards
john
 
I read in sci.electronics.design that Rich Grise <null@example.net>
wrote (in <kjG7d.935$1g5.372@trnddc07>) about '48 Nobel Laureates
Endorse Kerry', on Sat, 2 Oct 2004:

But standing a block away, putting you in my crosshairs, and sniping you
because you're the wrong religion (or have custody of a big pile of
oil), that's nothing but cold-blooded murder.
Click to expand...
How do you plan to stop people doing exactly that?

Some very long time ago A Frenchman made a comment on this. I'll put it
in English because the original is very French:

'To eliminate the death penalty, the murderers must take the first
step.'
--
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
 
"ChrisGibboGibson" <chrisgibbogibson@aol.com> wrote in message
news:20041002175124.11054.00001310@mb-m14.aol.com...
"john jardine" wrote:



"ChrisGibboGibson" <chrisgibbogibson@aol.com> wrote in message
news:20041002150752.11054.00001292@mb-m14.aol.com...
We have another product being laucnched in about 2 months time.
[-]

The last 2 products were just improved versions of competitors products.
This
is something totally new. I *know* they'll sell it. But a buzz phrase for
the
way it works would be nice.

Gibbo
Click to expand...
In which case I'd maybe go with Ken Smiths idea of getting your name on it
somewhere.
In my WW11 radio collection I've a type T1333, downed aircraft, emergency
distress transmitter. Nobody knows it as that. Because of it's shape, it's
simply called a "Gibson girl" unit.
regards
john
 
I read in sci.electronics.design that ChrisGibboGibson
<chrisgibbogibson@aol.com> wrote (in <20041002181947.11054.00001314@mb-
m14.aol.com>) about 'Marketing blurb - bullsh*t baffles etc', on Sat, 2
Oct 2004:
(Ken Smith) wrote:


interspectral Gibboscopy


Obviously I'd go with that but I doubt it would sell anything.
Click to expand...
It's a horrible Latin-Greek hybrid meaning 'hump watching'.
--
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
 
I read in sci.electronics.design that ftls1@uaf.edu <ftls1@uaf.edu>
wrote (in <44042ede.0410021517.4703bf98@posting.google.com>) about 'how
to make a counter/timer circuit for 35GHz', on Sat, 2 Oct 2004:

But now I have a square wave working at 35GHz
Click to expand...
How do you know? You need a minimum bandwidth of 180 GHz to even
approximate a square wave at 35 GHz. With negligible phase shift.
--
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
 
I read in sci.electronics.design that Tim Wescott
<tim@wescottnospamdesign.com> wrote (in <10lug3s5h4ff609@corp.supernews.
com>) about 'how to make a counter/timer circuit for 35GHz', on Sat, 2
Oct 2004:
If it's fairly narrowband the standard thing to do is to heterodyne it
down to something more reasonable and count that.
Click to expand...
A narrow-band square wave I'd very much like to see. (;-)
--
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
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top