On Wed, 20 Jul 2011 22:43:03 -0500, "DonMack" <DonMack@Maill.com> wrote:> > >"John S" wrote in message news:j07tfc$nqq$1@dont-email.me... > >On 7/20/2011 7:48 PM, Jim Thompson wrote: >> On Wed, 20 Jul 2011 17:23:52 -0700 (PDT), panfilero<panfilero@gmail.com> >> wrote: >> >>> can anyone tell what I did wrong here? my goal is to measure current >>> using an opamp, I need to be able to measure positive and negative >>> current, and I have these LTC2053 OpAmps available, but I'm trying to >>> simulate what I'm thinking about doing in LTspice and I can't get any >>> output at all.... I need to be able to see from 50uA to .1mA, which is >>> a pretty big range (and I need this in positive and negative >>> directions) here's a link to the circuit I made in LTspice, much >>> thanks >>> >>> >>> LTspice: >>> http://s555.photobucket.com/albums/jj477/panfilero/?action=view¤t=LTC2053.png >>> >>> LTC2053 datasheet: >>> http://cds.linear.com/docs/Datasheet/2053syncfc.pdf >>> >> >> Post your LTspice schematic, *.asc is text and you can it post here. >> >> Looks like it should be working, but a look at the LTspice file will tell >> us a >> lot. > >So, you can't simulate without the OP posting the text file? You are >less helpful than I suspected.I'm quite occupied at the moment... teaching and working two chip designs all at once. Of course I _could_ have entered it myself, but the OP could have posted it in a couple of clicks. I don't know who you are, but if you followed the LTspice Yahoo group you'd know I'm a fairly regular contributor of simulation techniques.> >> 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 :-) >> >> ...Jim Thompson > >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.As long as Larkin keeps "cluck, clucking", I _will_ appropriately point out his short........... comings ;-) As for you, Don Mack, I can't recall ANY technical contribution whatsoever. As for me, I am the master of circuit design... ask ANY of my clients/customers ;-)> >-------- > >and yet you respond to a response that is OT with an OT response.... You >should think twice about voting for Obonkers again. >You sure must live in a cave... I am the resident "kill any liberal on sight" proponent. You could be next :-) ...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.
op-amp circuit wont work
Started by ●July 20, 2011
Reply by ●July 21, 20112011-07-21
Reply by ●July 21, 20112011-07-21
On Wed, 20 Jul 2011 22:43:03 -0500, "DonMack" <DonMack@Maill.com> wrote:>>> Post your LTspice schematic, *.asc is text and you can it post here. >> >> Looks like it should be working, but a look at the LTspice file will tell >> us a >> lot. > >So, you can't simulate without the OP posting the text file? You are >less helpful than I suspected. >You can't troubleshoot something that isn't there. The schematic image is only a part of the user interface - the problem lies elsewhere. RL
Reply by ●July 21, 20112011-07-21
This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig78B85F05E05706462E58F81F Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Jim Thompson wrote: ------>> >> and yet you respond to a response that is OT with an OT response.... Y=ou=20>> should think twice about voting for Obonkers again. >> >=20 > You sure must live in a cave... I am the resident "kill any liberal on =sight"> proponent. >=20 > You could be next :-)Thank God for people like you. Do you prefer the 'Arbeit macht frei' or Gulag approach? When did you first discover that Democracy only works when it's going *your* way? mike --------------enig78B85F05E05706462E58F81F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (GNU/Linux) iQEcBAEBAgAGBQJOKEn4AAoJECGtZwCbtgwX2V0H/25A2/PkpI4KkpOLLup5im2X Bor3zQK6VhqCfxkiYblGcykB2x6o7z5068keRkpIih1GumfQJFxNYL/1g11BRLjy Br/AShXaNjRMLmpHzpnT4b87NXFaQW+QKDyqV5TBCCWvMKVA4iR5NCkXstDGsKxU mERoixw6s4Z3u9NaP4H/nn3NLoKpJyEJLSaKXLAm1JwzACphFSR3Fe80KLUCHxpB FcjY7C1mjLqmHskpIyFuT+YyhGRSfwOvNghihq/0/lWyyA4pxXVqPCiMipyvo0m2 8BaQ3RZRsSeUfVgADJYrOCUfH5xIRF57ahF4NO/WZlfjfnwKLZUtegq5U3y5e6Y= =rUgj -----END PGP SIGNATURE----- --------------enig78B85F05E05706462E58F81F--
Reply by ●July 21, 20112011-07-21
I don't mean to interrupt you guys but can anyone help me figure this out, I'm kinda stuck here, thanks "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?"
Reply by ●July 21, 20112011-07-21
On Jul 21, 1:25=A0pm, panfilero <panfil...@gmail.com> wrote:> I don't mean to interrupt you guys but can anyone help me figure this > out, I'm kinda stuck here, thanks > > "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?"Hi panfilero, the resistors you choose could make a difference in terms of bais current error or noise. I don't know that LT opamp. 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. George H.
Reply by ●July 21, 20112011-07-21
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 :-) -- JF
Reply by ●July 21, 20112011-07-21
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
Reply by ●July 21, 20112011-07-21
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. -- JF
Reply by ●July 21, 20112011-07-21
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? -- JF
Reply by ●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.
