Lookinf for options for an Absolute Magnitude" or precision

[Clarence_A]

Must work over substantial range, say .01 to .6 Volts RMS.

Serious responses only. Please.

I have a working circuit now, but there is some variation between
positive and negative half cycles which seems to be inherent.
Must be some easy way to eliminate this. Yes?

 

[Jim Thompson]

On Sat, 05 Feb 2005 19:01:17 GMT, "Clarence_A" <no@No.com> wrote:

Must work over substantial range, say .01 to .6 Volts RMS.

Serious responses only. Please.

I have a working circuit now, but there is some variation between
positive and negative half cycles which seems to be inherent.
Must be some easy way to eliminate this. Yes?

Frequency?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Clarence_A]

"Jim Thompson" <thegreatone@example.com> wrote in message
news:q56a01d0hpknjjq721f3c4fotc8ln8t6n0@4ax.com...

On Sat, 05 Feb 2005 19:01:17 GMT, "Clarence_A" <no@No.com
wrote:



Must work over substantial range, say .01 to .6 Volts RMS.

Serious responses only. Please.

I have a working circuit now, but there is some variation
between
positive and negative half cycles which seems to be inherent.
Must be some easy way to eliminate this. Yes?



Frequency?

380 to 800 HZ

 

[John Larkin]

On Sat, 05 Feb 2005 19:01:17 GMT, "Clarence_A" <no@No.com> wrote:

Must work over substantial range, say .01 to .6 Volts RMS.

Serious responses only. Please.

I did a mechanical version once. No matter which direction you turned
the input shaft, the output shaft went clockwise. The MEs were stumped
so I showed them how to do a rotary full-wave rectifier.

I have a working circuit now, but there is some variation between
positive and negative half cycles which seems to be inherent.
Must be some easy way to eliminate this. Yes?

Can you post your circuit?

John

 

[John Woodgate]

I read in sci.electronics.design that John Larkin <jjSNIPlarkin@highTHIS
landPLEASEtechnology.XXX> wrote (in <ltea015gvuthb414lq6kqc1kv806prgjef@
4ax.com&gt about 'Lookinf for options for an Absolute Magnitude" or
precision rectifier circuit.', on Sat, 5 Feb 2005:

I did a mechanical version once. No matter which direction you turned
the input shaft, the output shaft went clockwise. The MEs were stumped
so I showed them how to do a rotary full-wave rectifier.

With ratchet wheels or the spring-loaded orbital idler (which looks like
magic to me)?
--
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

 

[John Larkin]

On Sat, 5 Feb 2005 22:10:10 +0000, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that John Larkin <jjSNIPlarkin@highTHIS
landPLEASEtechnology.XXX> wrote (in <ltea015gvuthb414lq6kqc1kv806prgjef@
4ax.com&gt about 'Lookinf for options for an Absolute Magnitude" or
precision rectifier circuit.', on Sat, 5 Feb 2005:

I did a mechanical version once. No matter which direction you turned
the input shaft, the output shaft went clockwise. The MEs were stumped
so I showed them how to do a rotary full-wave rectifier.

With ratchet wheels or the spring-loaded orbital idler (which looks like
magic to me)?

Planetaries and orbitals and differentials are too complicated for me,
too. I used notched pulleys/belts to get counter-rotations and a pair
of one-way roller clutches to rectify them into the output shaft. It
actually drove a synchro for a shaft-rotaton counter on a ship. It was
really silly, since ships spend so little time going backwards you'd
never really miss those turns.

John

 

[Jim Thompson]

On Sat, 05 Feb 2005 22:09:31 GMT, "Clarence_A" <no@No.com> wrote:

"John Larkin" <jjSNIPlarkin@highTHISlandPLEASEtechnology.XXX
wrote in message
news:ltea015gvuthb414lq6kqc1kv806prgjef@4ax.com...
On Sat, 05 Feb 2005 19:01:17 GMT, "Clarence_A" <no@No.com
wrote:

Must work over substantial range, say .01 to .6 Volts RMS.

Serious responses only. Please.

I did a mechanical version once. No matter which direction you
turned
the input shaft, the output shaft went clockwise. The MEs were
stumped
so I showed them how to do a rotary full-wave rectifier.

I have a working circuit now, but there is some variation
between
positive and negative half cycles which seems to be inherent.
Must be some easy way to eliminate this. Yes?

Can you post your circuit?

Sure, But it's easier to post a link!

http://www.analog.com/UploadedFiles/Data_Sheets/813995969OP191_291_491_c.pdf

On page seventeen!

What a crock! Relies on rail-to-rail OpAmp with negative rail of
first stage tied to ground :-(

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Fred Bloggs]

Jim Thompson wrote:

What a crock! Relies on rail-to-rail OpAmp with negative rail of
first stage tied to ground :-(

Heheh- the reference level about which rectification is performed is
defined by the clamp level of the first amplifier buffer. Ok- make that
"rectalication" for the alien fascist, Clarence-

 

[John Larkin]

On Sun, 06 Feb 2005 16:35:14 GMT, "Clarence_A" <no@No.com> wrote:

Since I need to change what the "app note paste artist" put
together, I need to refute his premise that "it wouldn't be
published if it wasn't correct."

Ha! Read the "ideas for design" clips in ED or EDN. Typically
nonsense.

John

 

[John Larkin]

On Sun, 06 Feb 2005 15:21:42 GMT, Fred Bloggs <nospam@nospam.com>
wrote:

John Larkin wrote:

Crazy! It pulls the opamp input below ground, in violation of their
own abs-max ratings! That 2 volt p-p input must be on the very edge of
blowing the opamp up.


In addition to knowing nothing about the 291, you can't read- the AM
Rating was obviously intent on saying GND+/-10V,

ABSOLUTE MAXIMUM RATINGS 1, 2
Supply Voltage . . . . . . . .. . . . . . . 16 V
Input Voltage . . . . . . . . . . . . . . . GND to VS 10 V


Is that what "GND to VS 10V" means? It looked like a misprint of "GND
to VS+10V" to me. I admit I didn't study the entire datasheet, this
being a newsgroup and I having real work to do of my own.

Why can't people proof datasheets?

Never mind- will not waste time on that individual...

Oh, please don't waste any of your valuable time on any of us.

John

 

[John Larkin]

On Sun, 6 Feb 2005 08:12:52 +0000, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

Your roller clutches are equivalent to ratchet wheels, and diodes.

A good roller clutch is like a schottky diode, or almost an ideal
diode. They are amazing: no perceptable backlash or deadband, and very
little reverse leakage.

John

 

[Winfield Hill]

Jim Thompson wrote...

http://www.analog.com/UploadedFiles/Data_Sheets/813995969OP191_291_491_c.pdf
On page seventeen!

What a crock! Relies on rail-to-rail OpAmp with negative rail of
first stage tied to ground :-(

Yes it's ugly, but probably works fine, provided it's DC coupled...
The input stage safely draws a fraction of a mA for negative voltages
(see fig 3) but is OK; the other opamp works fine inverting the signal.

But I doubt this circuit can do well at low voltages. I have another
configuration I prefer for mV-level active rectification, which even
works well at MHz frequencies.


--
Thanks,
- Win

 

[Clarence_A]

"John Larkin" <jjSNIPlarkin@highTHISlandPLEASEtechnology.XXX>
wrote in message
news:aisc019r90e95v4mcrppq7b8our1ap7ktq@4ax.com...

On Sun, 06 Feb 2005 16:35:14 GMT, "Clarence_A" <no@No.com
wrote:

Since I need to change what the "app note paste artist" put
together, I need to refute his premise that "it wouldn't be
published if it wasn't correct."


Ha! Read the "ideas for design" clips in ED or EDN. Typically
nonsense.

John

You mean it "ISN'T" a joke? &gt

 

[Fred Bloggs]

John Larkin wrote:

Right now, I'm writing the self-test code for the B-52 bomber radar
thing, which is a real drag. So, tell us about something cool you're
working on now and make us jealous.

Ehhh- big deal- that is a relatively small job...not to mention the
work statement has been reduced to the primitive level...yawn.

 

[richard mullens]

Jim Thompson wrote:

I plonked Mullens ages ago. Didn't you notice the "ntlworld"... he's
another Bemelman-style cretin.

I guess that in 8 years time when I'm as old as you are now, I'll have become less tolerant of other people's views too.

For the moment I read what you say - even though I don't always agree with it - you come across as a likeable rogue.

 

[keith]

On Sun, 06 Feb 2005 13:23:42 -0700, Jim Thompson wrote:

On Sun, 06 Feb 2005 20:17:48 GMT, fuclarence <xyz@xyz123456789.com
wrote:

[snip]

Why don't you plonk this and run- you little tutu wearing flake...


Sheeesh! What have we come to? Even Fred has to resort to an alias
to get read.

FuFred ;-)

FauxPhred? Or maybe Fox(news)Fred? (oh, I can't wait for the spew!)

--
Keith