Forums

op-amp circuit wont work

Started by panfilero July 20, 2011
On 7/20/2011 8:35 PM, John Larkin wrote:
> 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 >
Do you really think that makes your point?

"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&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. -------- and yet you respond to a response that is OT with an OT response.... You should think twice about voting for Obonkers again.
On Wed, 20 Jul 2011 20:37:37 -0500, John S <sophi.2@invalid.org>
wrote:

>On 7/20/2011 8:35 PM, John Larkin wrote: >> 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 >> > >Do you really think that makes your point?
My point is that there is no point! John
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
On Wed, 20 Jul 2011 20:15:44 -0500, John S <sophi.2@invalid.org> wrote:

>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.
Sure, I can do that but then I don't see any hidden modification he might have made. It's easier for him to post the netlist than it is to link a picture.
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. >
You're the only one who still trollbaits him. Hope This Helps! Rich
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. >> >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. But since he's killfiled me, you can't accuse me of baiting the batty old hen. He can't see my posts. John
On Jul 20, 9:36=A0pm, John Larkin
<jjSNIPlar...@highTHISlandtechnology.com> wrote:
> On Wed, 20 Jul 2011 21:12:10 -0700, Rich Grise > > > > <ri...@example.net.invalid> wrote: > >John Larkin wrote: > >> On Wed, 20 Jul 2011 19:56:09 -0500, John S <soph...@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. > > >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. > > But since he's killfiled me, you can't accuse me of baiting the batty > old hen. He can't see my posts. > > John
You seem to be on the defense. Must be nice to be killfilled by someone from MIT? Wish I could brag about that. -Bill
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John Larkin wrote:

>> Do you really think that makes your point? >=20 > My point is that there is no point!
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On Wed, 20 Jul 2011 21:54:14 -0700 (PDT), Bill Bowden
<bperryb@bowdenshobbycircuits.info> wrote:

>On Jul 20, 9:36&#2013266080;pm, John Larkin ><jjSNIPlar...@highTHISlandtechnology.com> wrote: >> On Wed, 20 Jul 2011 21:12:10 -0700, Rich Grise >> >> >> >> <ri...@example.net.invalid> wrote: >> >John Larkin wrote: >> >> On Wed, 20 Jul 2011 19:56:09 -0500, John S <soph...@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. >> >> >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. >> >> But since he's killfiled me, you can't accuse me of baiting the batty >> old hen. He can't see my posts. >> >> John > >You seem to be on the defense.
Defense? From what? Must be nice to be killfilled by
>someone from MIT? Wish I could brag about that.
I wish he'd actually do it. What sort of idiot would keep telling me that he has killfiled me? John