Forums

op-amp circuit wont work

Started by panfilero July 20, 2011
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&current=LTC2053.png

LTC2053 datasheet:
http://cds.linear.com/docs/Datasheet/2053syncfc.pdf


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&current=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. 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 [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.
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&current=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.
> 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.
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&current=LTC2053.png > >LTC2053 datasheet: >http://cds.linear.com/docs/Datasheet/2053syncfc.pdf >
Define "can't get any output at all". Seems to me that you should have 150mV (one way or the other) at the output. Posting the netlist is the best way to get help. Most of us can stick it in LTSpice to look at the schematic.
On 7/20/2011 8:05 PM, krw@att.bizzzzzzzzzzzz 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&current=LTC2053.png >> >> LTC2053 datasheet: >> http://cds.linear.com/docs/Datasheet/2053syncfc.pdf >> > Define "can't get any output at all". Seems to me that you should have 150mV > (one way or the other) at the output. Posting the netlist is the best way to > get help. Most of us can stick it in LTSpice to look at the schematic. >
Try this: In LTSpice, open a new schematic. Place an LTC2053. Right click on it and then click "open this macromodel's test fixture". Then modify accordingly. Hope this helps.
On Jul 20, 8:05=A0pm, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:
> On Wed, 20 Jul 2011 17:23:52 -0700 (PDT), panfilero <panfil...@gmail.com> > wrote: > > > > > > > > > > >can anyone tell what I did wrong here? =A0my 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=3Dview&curre.=
..
> > >LTC2053 datasheet: > >http://cds.linear.com/docs/Datasheet/2053syncfc.pdf > > Define "can't get any output at all". =A0Seems to me that you should have=
150mV
> (one way or the other) at the output. =A0Posting the netlist is the best =
way to
> get help. =A0Most of us can stick it in LTSpice to look at the schematic.
Basically I get a steady -0.5mV at the output, if I make my load resistance smaller, this value goes to zero. thanks "ExpressPCB Netlist" "SwCAD III Version 4.11z" 1 0 0 "" "" "" "Part IDs Table" "V1" "5" "" "U1" "LTC2053" "" "R1" "1K" "" "R2" "2K" "" "R3" "1" "" "R4" "100k" "" "V2" "-5" "" "I1" ".05" "" "Net Names Table" "N001" 1 "0" 3 "Vin" 12 "N002" 15 "N003" 17 "Vout" 20 "Net Connections Table" 1 1 1 2 1 2 8 0 2 1 2 4 2 2 1 5 2 2 2 6 2 2 5 7 2 3 2 8 2 5 2 9 2 6 2 10 2 7 2 11 2 8 1 0 3 2 3 13 3 5 1 14 3 8 2 0 4 2 4 16 4 7 1 0 5 2 6 18 5 3 1 19 5 4 1 0 6 2 7 21 6 4 2 22 6 6 1 0
On Wed, 20 Jul 2011 19:56:09 -0500, John S <sophi.2@invalid.org>
wrote:

>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&current=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. > >> 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. >
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. John
On Jul 20, 8:15=A0pm, John S <soph...@invalid.org> wrote:
> On 7/20/2011 8:05 PM, k...@att.bizzzzzzzzzzzz wrote: > > > > > > > > > > > On Wed, 20 Jul 2011 17:23:52 -0700 (PDT), panfilero<panfil...@gmail.com= > > > wrote: > > >> can anyone tell what I did wrong here? =A0my goal is to measure curren=
t
> >> 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=3Dview&curre=
...
> > >> LTC2053 datasheet: > >>http://cds.linear.com/docs/Datasheet/2053syncfc.pdf > > > Define "can't get any output at all". =A0Seems to me that you should ha=
ve 150mV
> > (one way or the other) at the output. =A0Posting the netlist is the bes=
t way to
> > get help. =A0Most of us can stick it in LTSpice to look at the schemati=
c.
> > Try this: > > In LTSpice, open a new schematic. > > Place an LTC2053. > > Right click on it and then click "open this macromodel's test fixture". > > Then modify accordingly. > > Hope this helps.
thank you, I opened up the test fixture like you suggested and noticed that the enable pin was wired to the negative rail.... I had mine wired to ground, thinking that since it's an active low input this would do it.... I've since hooked mine up to my negative power supply and it's working now.
On 7/20/2011 8:27 PM, John Larkin wrote:
> On Wed, 20 Jul 2011 19:56:09 -0500, John S<sophi.2@invalid.org> > wrote: > >> 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&current=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. >> >>> 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. >> > > 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. > > John
Your reply was not necessary, John.
On Wed, 20 Jul 2011 20:30:42 -0500, John S <sophi.2@invalid.org>
wrote:

>On 7/20/2011 8:27 PM, John Larkin wrote: >> On Wed, 20 Jul 2011 19:56:09 -0500, John S<sophi.2@invalid.org> >> wrote: >> >>> 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&current=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. >>> >>>> 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. >>> >> >> 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. >> >> John > >Your reply was not necessary, John.
This is a newsgroup. None of it is necessary! John