Reply by John S ●July 30, 20112011-07-30
On 7/30/2011 3:20 PM, John Fields wrote:

> On Sat, 30 Jul 2011 14:36:58 -0500, John S<sophi.2@invalid.org>
> wrote:
>
>> On 7/21/2011 5:15 PM, John S wrote:
>>> On 7/21/2011 4:59 PM, John Fields wrote:
>>>> On Wed, 20 Jul 2011 21:00:18 -0700 (PDT), panfilero
>>>> <panfilero@gmail.com>  wrote:
>>>>
>>>>> I have a follow up question about this circuit, I'm really interested
>>>>> in being able to measure 50uV at the input, by adding gain and seeing
>>>>> something at the output.... I was thinking with a gain of 21, this
>>>>> would get me 1.05mV at the output and I could work with that. But,
>>>>> when I apply zero volts at the input I get 20mV at my output. In the
>>>>> datasheet it says the offset voltage is below 10uV... why am I seeing
>>>>> this 20mV? I tried just connecting both input pins to ground and
>>>>> still get 20mV at the output.... also, is there any particular range
>>>>> of resistors that I should use in my feedback? I mean, if I want a
>>>>> gain of 21, I need a ratio of 20 from R2/R1.... does it matter if I
>>>>> use 20k/1k or 200k/10k or 2k/100?
>>>>>
>>>>> much thanks
>>>>
>>>> ---
>>>> Panfilero, do this, please:
>>>>
>>>> 1. Using a vanilla text editor like Notepad, set it to
>>>> "View All Files" and open the .asc file holding your schematic.
>>>>
>>>> 2. Select all of the text and paste it to the clipboard with "CTRL C".
>>>>
>>>> 3. Respond to this post by pasting the text (CTRL V) a couple of lines
>>>> below this one, and sending it.
>>>>
>>>> What that'll do is allow us all to run your simulation without each of
>>>> us having to manually recreate your circuit from the screen capture.
>>>>
>>>> Thanks :-)
>>>>
>>>
>>>
>>> Step 1 can also be done inside LTSpice with View/Spice Netlist
>>
>> I owe you an apology. It *appeared* that it could be done, but I was
>> wrong. Too much is missing from that netlist to give a schematic. I did
>> not try it before submitting the suggestion. Dang me. Sorry.
>>
>> Your steps are the best route.
>
> ---
> Thanks for that, and thanks for the heads-up as well; I didn't try it
> either.
>
> As for the apology: You, Sir, are a true gentleman. :-)
>


And, you are a true gentleman for writing that. I believe in admitting 
my mistakes, whether minor or major.

Cheers,
John S
Reply by John Fields ●July 30, 20112011-07-30
On Sat, 30 Jul 2011 14:36:58 -0500, John S <sophi.2@invalid.org>
wrote:


>On 7/21/2011 5:15 PM, John S wrote:
>> On 7/21/2011 4:59 PM, John Fields wrote:
>>> On Wed, 20 Jul 2011 21:00:18 -0700 (PDT), panfilero
>>> <panfilero@gmail.com> wrote:
>>>
>>>> I have a follow up question about this circuit, I'm really interested
>>>> in being able to measure 50uV at the input, by adding gain and seeing
>>>> something at the output.... I was thinking with a gain of 21, this
>>>> would get me 1.05mV at the output and I could work with that. But,
>>>> when I apply zero volts at the input I get 20mV at my output. In the
>>>> datasheet it says the offset voltage is below 10uV... why am I seeing
>>>> this 20mV? I tried just connecting both input pins to ground and
>>>> still get 20mV at the output.... also, is there any particular range
>>>> of resistors that I should use in my feedback? I mean, if I want a
>>>> gain of 21, I need a ratio of 20 from R2/R1.... does it matter if I
>>>> use 20k/1k or 200k/10k or 2k/100?
>>>>
>>>> much thanks
>>>
>>> ---
>>> Panfilero, do this, please:
>>>
>>> 1. Using a vanilla text editor like Notepad, set it to
>>> "View All Files" and open the .asc file holding your schematic.
>>>
>>> 2. Select all of the text and paste it to the clipboard with "CTRL C".
>>>
>>> 3. Respond to this post by pasting the text (CTRL V) a couple of lines
>>> below this one, and sending it.
>>>
>>> What that'll do is allow us all to run your simulation without each of
>>> us having to manually recreate your circuit from the screen capture.
>>>
>>> Thanks :-)
>>>
>>
>>
>> Step 1 can also be done inside LTSpice with View/Spice Netlist
>
>I owe you an apology. It *appeared* that it could be done, but I was 
>wrong. Too much is missing from that netlist to give a schematic. I did 
>not try it before submitting the suggestion. Dang me. Sorry.
>
>Your steps are the best route.


---
Thanks for that, and thanks for the heads-up as well; I didn't try it
either.

As for the apology: You, Sir, are a true gentleman. :-)

-- 
JF
Reply by John S ●July 30, 20112011-07-30
On 7/21/2011 5:15 PM, John S wrote:

> On 7/21/2011 4:59 PM, John Fields wrote:
>> On Wed, 20 Jul 2011 21:00:18 -0700 (PDT), panfilero
>> <panfilero@gmail.com> wrote:
>>
>>> I have a follow up question about this circuit, I'm really interested
>>> in being able to measure 50uV at the input, by adding gain and seeing
>>> something at the output.... I was thinking with a gain of 21, this
>>> would get me 1.05mV at the output and I could work with that. But,
>>> when I apply zero volts at the input I get 20mV at my output. In the
>>> datasheet it says the offset voltage is below 10uV... why am I seeing
>>> this 20mV? I tried just connecting both input pins to ground and
>>> still get 20mV at the output.... also, is there any particular range
>>> of resistors that I should use in my feedback? I mean, if I want a
>>> gain of 21, I need a ratio of 20 from R2/R1.... does it matter if I
>>> use 20k/1k or 200k/10k or 2k/100?
>>>
>>> much thanks
>>
>> ---
>> Panfilero, do this, please:
>>
>> 1. Using a vanilla text editor like Notepad, set it to
>> "View All Files" and open the .asc file holding your schematic.
>>
>> 2. Select all of the text and paste it to the clipboard with "CTRL C".
>>
>> 3. Respond to this post by pasting the text (CTRL V) a couple of lines
>> below this one, and sending it.
>>
>> What that'll do is allow us all to run your simulation without each of
>> us having to manually recreate your circuit from the screen capture.
>>
>> Thanks :-)
>>
>
>
> Step 1 can also be done inside LTSpice with View/Spice Netlist


I owe you an apology. It *appeared* that it could be done, but I was 
wrong. Too much is missing from that netlist to give a schematic. I did 
not try it before submitting the suggestion. Dang me. Sorry.

Your steps are the best route.

John S
Reply by m II ●July 23, 20112011-07-23
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Jim Thompson wrote:


> You sure must live in a cave... I am the resident "kill any liberal on =

sight"

> proponent.
>=20
> You could be next :-)



Traveling? I hear Oslo is beautiful this time of year. Everything's just
so RIGHT.


mike







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Reply by whit3rd ●July 22, 20112011-07-22
On Thursday, July 21, 2011 5:10:32 PM UTC-4, George Herold wrote:

[about converting current to voltage] 


>....  How about using a 'regular' opamp as a
> transimpedance amp to measure the current.  Currents from 50 uA to 100
> uA are no big deal at all.  (I've measured pA with a TIA and a Gig-ohm
> resistor)  A 100k ohm resistor in the feedback would give 10 Volts on
> the output for 100uA of current.


I second this; the op amp (-) node takes the input current and has
a feedback resistor from the output, then a second (match to the feedback)
resistor goes from (+) to ground.
Reply by John Fields ●July 22, 20112011-07-22
On Thu, 21 Jul 2011 20:37:39 -0500, John S <sophi.2@invalid.org>
wrote:


>On 7/21/2011 7:10 PM, John Fields wrote:
>> On Thu, 21 Jul 2011 17:15:43 -0500, John S<sophi.2@invalid.org>
>> wrote:



>>> Step 1 can also be done inside LTSpice with View/Spice Netlist
>>
>> ---
>> OK, but then how would you get the file to USENET?
>>
>
>By following your steps 2 and 3.


---
Dunno how I missed that one! :-(

Thanks! :-)

-- 
JF
Reply by panfilero ●July 22, 20112011-07-22
On Jul 21, 4:59=A0pm, John Fields <jfie...@austininstruments.com> wrote:

> On Wed, 20 Jul 2011 21:00:18 -0700 (PDT),panfilero
>
> <panfil...@gmail.com> wrote:
> >I have a follow up question about this circuit, I'm really interested
> >in being able to measure 50uV at the input, by adding gain and seeing
> >something at the output.... I was thinking with a gain of 21, this
> >would get me 1.05mV at the output and I could work with that. =A0But,
> >when I apply zero volts at the input I get 20mV at my output. =A0In the
> >datasheet it says the offset voltage is below 10uV... why am I seeing
> >this 20mV? =A0I tried just connecting both input pins to ground and
> >still get 20mV at the output.... also, is there any particular range
> >of resistors that I should use in my feedback? I mean, if I want a
> >gain of 21, I need a ratio of 20 from R2/R1.... does it matter if I
> >use 20k/1k or 200k/10k or 2k/100?
>
> >much thanks
>
> ---Panfilero, do this, please:
>
> 1. Using a vanilla text editor like Notepad, set it to
> =A0 =A0"View All Files" and open the .asc file holding your schematic.
>
> 2. Select all of the text and paste it to the clipboard with "CTRL C".
>
> 3. Respond to this post by pasting the text (CTRL V) a couple of lines
> =A0 =A0below this one, and sending it.
>
> What that'll do is allow us all to run your simulation without each of
> us having to manually recreate your circuit from the screen capture.
>
> Thanks :-)
>
> --
> JF


thanks john


Version 4
SHEET 1 880 680
WIRE 288 -192 176 -192
WIRE 0 -128 -160 -128
WIRE 176 -128 176 -192
WIRE 0 -32 0 -128
WIRE 176 -16 176 -48
WIRE -160 48 -160 -128
WIRE 288 96 288 -192
WIRE 0 144 0 48
WIRE 32 144 0 144
WIRE 160 144 32 144
WIRE 0 160 0 144
WIRE 496 160 352 160
WIRE 656 160 496 160
WIRE 672 160 656 160
WIRE 160 176 112 176
WIRE 672 192 672 160
WIRE 240 256 240 224
WIRE 240 256 208 256
WIRE 0 272 0 240
WIRE 112 272 112 176
WIRE 112 272 0 272
WIRE 208 272 208 256
WIRE 288 272 288 224
WIRE 320 272 320 224
WIRE 320 272 288 272
WIRE 0 304 0 272
WIRE 672 304 672 272
WIRE 288 320 288 272
WIRE 288 320 96 320
WIRE 256 336 256 224
WIRE 368 336 256 336
WIRE 496 336 496 160
WIRE 496 336 448 336
WIRE 96 384 96 320
WIRE 256 416 256 336
WIRE 96 512 96 464
WIRE 256 608 256 496
FLAG 176 -16 0
FLAG 672 304 0
FLAG 96 512 0
FLAG -160 48 0
FLAG 0 304 0
FLAG 656 160 Vout
FLAG 208 272 0
FLAG 256 608 0
FLAG 32 144 Vin
SYMBOL voltage 176 -144 R0
WINDOW 123 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
SYMATTR SpiceLine Rser=3D.000001
SYMBOL Opamps\\LTC2053 272 160 R0
SYMATTR InstName U1
SYMBOL res 240 400 R0
SYMATTR InstName R1
SYMATTR Value 1K
SYMATTR SpiceLine tol=3D1 pwr=3D0.1
SYMBOL res 352 352 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R2
SYMATTR Value 200k
SYMATTR SpiceLine tol=3D1 pwr=3D0.1
SYMBOL res -16 144 R0
SYMATTR InstName R3
SYMATTR Value 1
SYMBOL res 656 176 R0
SYMATTR InstName R4
SYMATTR Value 500000000
SYMATTR SpiceLine tol=3D1 pwr=3D0.1
SYMBOL voltage 96 368 R0
WINDOW 123 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value -5
SYMATTR SpiceLine Rser=3D.0001
SYMBOL current 0 -32 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName I1
SYMATTR Value -0.017
TEXT -120 592 Left 0 !.tran 0 0.25 0 .01 uic
Reply by John S ●July 21, 20112011-07-21
On 7/21/2011 7:10 PM, John Fields wrote:

> On Thu, 21 Jul 2011 17:15:43 -0500, John S<sophi.2@invalid.org>
> wrote:
>
>> On 7/21/2011 4:59 PM, John Fields wrote:
>>> On Wed, 20 Jul 2011 21:00:18 -0700 (PDT), panfilero
>>> <panfilero@gmail.com>   wrote:
>>>
>>>> I have a follow up question about this circuit, I'm really interested
>>>> in being able to measure 50uV at the input, by adding gain and seeing
>>>> something at the output.... I was thinking with a gain of 21, this
>>>> would get me 1.05mV at the output and I could work with that.  But,
>>>> when I apply zero volts at the input I get 20mV at my output.  In the
>>>> datasheet it says the offset voltage is below 10uV... why am I seeing
>>>> this 20mV?  I tried just connecting both input pins to ground and
>>>> still get 20mV at the output.... also, is there any particular range
>>>> of resistors that I should use in my feedback? I mean, if I want a
>>>> gain of 21, I need a ratio of 20 from R2/R1.... does it matter if I
>>>> use 20k/1k or 200k/10k or 2k/100?
>>>>
>>>> much thanks
>>>
>>> ---
>>> Panfilero, do this, please:
>>>
>>> 1. Using a vanilla text editor like Notepad, set it to
>>>      "View All Files" and open the .asc file holding your schematic.
>>>
>>> 2. Select all of the text and paste it to the clipboard with "CTRL C".
>>>
>>> 3. Respond to this post by pasting the text (CTRL V) a couple of lines
>>>      below this one, and sending it.
>>>
>>> What that'll do is allow us all to run your simulation without each of
>>> us having to manually recreate your circuit from the screen capture.
>>>
>>> Thanks :-)
>>>
>>
>>
>> Step 1 can also be done inside LTSpice with View/Spice Netlist
>
> ---
> OK, but then how would you get the file to USENET?
>


By following your steps 2 and 3.
Reply by John Larkin ●July 21, 20112011-07-21
On Thu, 21 Jul 2011 19:00:14 -0500, John Fields
<jfields@austininstruments.com> wrote:


>On Wed, 20 Jul 2011 21:36:14 -0700, John Larkin
><jjSNIPlarkin@highTHISlandtechnology.com> wrote:
>
>>On Wed, 20 Jul 2011 21:12:10 -0700, Rich Grise
>><richg@example.net.invalid> wrote:
>>
>>>John Larkin wrote:
>>>> On Wed, 20 Jul 2011 19:56:09 -0500, John S <sophi.2@invalid.org>
>>>>>On 7/20/2011 7:48 PM, Jim Thompson wrote:
>>>>>
>>>>>> Or you can ask Larkin and he'll tell you how wonderful he is and he will
>>>>>> go on and on for days... and you will know less than you do today :-)
>>>>>
>>>>>Of course. You just had to get that off-topic dig in didn't you? You
>>>>>have become repulsive in my opinion for your inability to control
>>>>>yourself. Shame on you.
>>>> 
>>>> He's bragging that he has kill-filed me, and he's obviously obsessed
>>>> by me, and pretty much dedicates all his posts to me. Figure that out.
>
>---
>Bragging ... me???
>Obsessed ... me???
>Dedicates... me???
>
>That's not at all hard to figure out; it sounds exactly like you're a
>narcissistic faggot who wants dominion over Jim by having him _want_
>to lick your "pussy", but the only way you can get that to happen is
>to demean him to the point where he'll suck your dick for forgiveness,
>if only figuratively.


You are getting gayer and gayer all the time. Gross.



>
>In my book, that ain't ever gonna happen,


Good grief, I hope not. I don't ever want to be in the same state with
the grimy old creep. Preferably not the same planet.

John
Reply by Jim Thompson ●July 21, 20112011-07-21
On Thu, 21 Jul 2011 19:00:14 -0500, John Fields
<jfields@austininstruments.com> wrote:


>On Wed, 20 Jul 2011 21:36:14 -0700, John Larkin
><jjSNIPlarkin@highTHISlandtechnology.com> wrote:
>
>>On Wed, 20 Jul 2011 21:12:10 -0700, Rich Grise
>><richg@example.net.invalid> wrote:
>>
>>>John Larkin wrote:
>>>> On Wed, 20 Jul 2011 19:56:09 -0500, John S <sophi.2@invalid.org>
>>>>>On 7/20/2011 7:48 PM, Jim Thompson wrote:
>>>>>
>>>>>> Or you can ask Larkin and he'll tell you how wonderful he is and he will
>>>>>> go on and on for days... and you will know less than you do today :-)
>>>>>
>>>>>Of course. You just had to get that off-topic dig in didn't you? You
>>>>>have become repulsive in my opinion for your inability to control
>>>>>yourself. Shame on you.
>>>> 
>>>> He's bragging that he has kill-filed me, and he's obviously obsessed
>>>> by me, and pretty much dedicates all his posts to me. Figure that out.
>
>---
>Bragging ... me???
>Obsessed ... me???
>Dedicates... me???
>
>That's not at all hard to figure out; it sounds exactly like you're a
>narcissistic faggot who wants dominion over Jim by having him _want_
>to lick your "pussy", but the only way you can get that to happen is
>to demean him to the point where he'll suck your dick for forgiveness,
>if only figuratively.
>
>In my book, that ain't ever gonna happen, so you'll just have to keep
>on doing whatever it is you do to keep from putting a bullet through
>your head.
>
>Hmm...
>
>Skinny girls are something like boys and can ameliorate the pain.
>
>"Mo" is it?
>---
>
>>>You're the only one who still trollbaits him.
>>
>>
>>Look at the structure of this sequence. I did not respond to his
>>posts. He did, admittedly lamely, attack me by name in response to a
>>purely technical post by someone else. My response was to John S.
>
>---
>>Crazy old geezer. Has nothing to say about electronics any more. Must
>>have run out of broken lampshades to repair.
>
>---
>Unfair.
>
>Like it or not, we often run into requests for help outside of our
>normal bailiwick and, if we can, we help.
>
>If we can't, we shouldn't damn the querant.
>
>After all, none of us knows everything, while all of us know more than
>any of us does.
>---
>
>>But since he's killfiled me, you can't accuse me of baiting the batty
>>old hen. He can't see my posts.
>
>---
>But, since he doesn't have _everyone_ killfiled, you troll him through
>knowing that he'll inadvertently read your derogatory comments
>embedded in someone else's post.
>
>If you were truly interested in being reasonable you'd ignore the
>occasional off-hand snipe.


Larkin craves attention.  He's like the kid who acts out because his parents
ignore him.

If everyone here would ignore Larkin instead of feeding the troll we'd be rid
of him forever.
 
                                       ...Jim Thompson

                  [On the Road, in New York]
-- 
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.