Can a single single supply op amp be used as a summing circuit?

--
Customers nonetheless, and at least _I_ have some!

te:

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in + 1?

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Congratulations, you are a moderately successful confidence trickster, but don't let it go to your head.

Why? I'm not a Texan. In fact I listen to the news on Dutch radio, which involves processing Dutch polysyllables.

Competent electronic designers understand "stable" to mean "not varying" - something a horse's ass like you could be expected to miss.

-- Bill Sloman, Nijmegen

Now if he would just cut off his fingers...

--
The movie \'Deliverance\' isn\'t a documentary!

:

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You'd like that. You could post your silly misconceptions with a slightly lower risk of being shown up as an ill-informed nitwit. How many combat aricraft did Russia built in WW2? How many combat aircraft did the US send to Russian under Lend-Lease?

-- Bill Sloman, Nijmegen

--
Since \'reality\' is subjective, your perpetual parroting of the phrase:
"Jim is as far out of touch with reality as ever." in lieu of anything
more substantive, makes the case that you have no proof but, like any
other loudmouth, would like to believe that saying it often enough would
make it seem true.

JF

dual

inverter.

1?

at

Build it and try it. Then tinker with it. But quit throwing a temper tantrum.

Boris: Yes, but subjectivity is objective. Sonja: Not in a rational scheme of perception. Boris: Perception is irrational. It implies immanence. Sonja: But judgment of any system of phenomena exists in any rational, metaphysical or epistemological contradiction to an abstracted empirical concept such as being, or to be, or to occur in the thing itself, or of the thing itself. Boris: Yeah, I've said that many times.

"Love and Death"

--
Rich Webb     Norfolk, VA

--
Geez, Bill, I have documentation to prove _why_ my stuff works, and
working stuff to prove _that_ my stuff works, while all you do is
prattle on about how great you used to be in your salad days.

Now that the salad has wilted, however, you seem to be largely unable to
produce much more than invective.

Isn't that the leftist weenie mantra? ...Jim Thompson

--
| 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     |
             
Coming soon to the elementary school in your neighborhood...

I pledge allegiance to Dear Leader Barack Hussein Obama and to the
community organization for which he stands: one nation under 
ACORN, unchallengeable, with wealth redistribution and climate
change for all.

s

From time to time I have documented where Jim's perceptions fall out of line with objective fact. In ths particular case he's so obviously and evidently wrong that it would insult the intelligence of the average reader to spell out the detail.

You may not be intellectually equipped to appreciate this, but you should note that when challenged to identify the flaw in my circuit that makes me unemployable, you objected to the least controversial components - R1, R2 and V2 - and couldn't say why you thought that they were objectionable, which makes you the loudmouth making a claim that he couldn't substantiate.

-- Bill Sloman, Nijmegen

On Oct 13, 4:03 pm, John Fields wrote:

which you - very conveniently - can't reveal because it is all commercial in confidence.

Since I can't even get at the documentation I wrote, which was also covered by confidentiality agreements, I'm not even in a positon to betray my former employer's customers.

At the moment I am tinkering with circuit that I invented back in

1986, for a company that went bankrupt a few years later - it was a wholly-owned subsidiary of Cambridge Instruments in 1986, but a subsequent management buy-out failed to work out. Simulations look good, but I've got a build some real hardware before I can go public.

Not entirely true, but you are ill-placed to understand the non- invective fraction, so it may well look that way to you.

I hope you can do as well in your second language - Spanish has many fewer vowels than Dutch (5 versus 18 of which 14 are simple vowels and

4 are diphthongs - so even you should be able to manage it.

It that were the case, why did my design specify a voltage reference, which has well defined tolerances, while yours relied on a power rail (which you didn't bother to constrain).?

Adding "news:" does make it meaningful. The design it points to - of which I became aware as the thread lengthened - isn't exactly flexible or likely to be particulalry precise.

My solution allows the OP to vary gain and offset independently. In the real world he'd probably want a scheme that worked with a +5V rail and guaranteed a voltage swing that wouldn't go outside 1V and 5V, nor run out of a rail-to-rail amplifier's voltage swing, like this

Version 4 SHEET 1 980 680 WIRE 0 -304 -176 -304 WIRE 816 -304 0 -304 WIRE 704 -240 608 -240 WIRE 976 -240 704 -240 WIRE 704 -192 704 -240 WIRE 608 -176 608 -240 WIRE 0 -160 0 -304 WIRE 512 -112 96 -112 WIRE 512 -96 512 -112 WIRE 608 -48 608 -112 WIRE 704 -48 704 -112 WIRE 704 -48 608 -48 WIRE 816 -48 816 -304 WIRE 704 -32 704 -48 WIRE 784 -32 704 -32 WIRE 976 -16 976 -240 WIRE 976 -16 848 -16 WIRE 512 0 512 -16 WIRE 784 0 512 0 WIRE 512 32 512 0 WIRE 704 128 704 -32 WIRE -176 144 -176 -304 WIRE 96 144 96 -112 WIRE 512 144 512 112 WIRE -176 352 -176 224 WIRE 0 352 0 -96 WIRE 0 352 -176 352 WIRE 96 352 96 224 WIRE 96 352 0 352 WIRE 512 352 512 224 WIRE 512 352 96 352 WIRE 704 352 704 208 WIRE 704 352 512 352 WIRE 816 352 816 16 WIRE 816 352 704 352 WIRE -176 400 -176 352 FLAG -176 400 0 SYMBOL voltage -176 128 R0 WINDOW 123 0 0 Left 0 WINDOW 39 24 132 Left 0 SYMATTR SpiceLine Rser=0.1 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL voltage 512 128 R0 WINDOW 123 0 0 Left 0 WINDOW 39 24 132 Left 0 SYMATTR SpiceLine Rser=0.1 SYMATTR InstName V2 SYMATTR Value 1.25 SYMBOL voltage 96 128 R0 WINDOW 123 0 0 Left 0 WINDOW 39 24 132 Left 0 SYMATTR SpiceLine Rser=0.1 SYMATTR InstName V3 SYMATTR Value PULSE(0 5 1u 1m 1m 1m 5m 1) SYMBOL res 528 128 R180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R1 SYMATTR Value 47k SYMATTR SpiceLine tol=0.1 SYMBOL res 528 0 R180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R2 SYMATTR Value 48k7 SYMATTR SpiceLine tol=0.1 SYMBOL res 688 112 R0 SYMATTR InstName R3 SYMATTR Value 68k SYMATTR SpiceLine tol=0.1 SYMBOL res 688 -208 R0 SYMATTR InstName R4 SYMATTR Value 40k2 SYMATTR SpiceLine tol=0.1 SYMBOL cap -16 -160 R0 SYMATTR InstName C1 SYMATTR Value 100n SYMBOL Opamps\\\\LTC6241 816 -16 R0 SYMATTR InstName U1 SYMBOL cap 592 -176 R0 SYMATTR InstName C2 SYMATTR Value 3p3 TEXT 168 408 Left 0 !.tran 0 5m 1u 100n startup

The LTC6241 is guaranteed to get within 75mV of the positve rail when sourcing 1mA, closer with a lighter load. This circuit, with worst case 0;1% E96 resistors and a worst case LT1790BCS6-1.25 as the voltage reference, will do this with your perfect 5.000V power supply rail.

Can you produce a version which will deal with a worst case 4.75V from the "5V" rail?

-- Bill Sloman, Nijmegen

--
You seem to delight in insulting the intelligence of the average reader,
so why would you have qualms about it now?

If Slowman ever tried to be specific with some real facts, he'd have a stroke ;-) ...Jim Thompson

--
| 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 have a dream that [we] will one day live in a nation where
[Obama] will not be judged by the color of [his] skin but by the 
content of [his] character."  

                  Obama will then be impeached.  

"Free at last! free at last! Thank God Almighty, we [will be] free
at last!"

akes

e

-)

ld

Sure. And you can leap over tall buildings with a single bound.

Nice try. What you are actually saying is that you don't appreciate the inadequacy of your own solution.

-- Bill Sloman, Nijmegen

:

makes

pe

;-)

: g

uld

Maybe Jim would like to produce a properly toleranced circuit to rescale and offset the OP's 0 to 5V signal so that it could be guaranteed to fit into the range of a 1-5V A/D converter, in a single- supply system with a +5V +/-0.25V power rail,

Obviously, you can't take advantage of the full range of the A/D converter, and you can't use the 5V rail as the source of your offset.

No stroke so far. Jim remains as far out of touch with reality as ever.

-- Bill Sloman, Nijmegen

Are you suggesting that only 5 Volts be used in the loop ?

If so, I guess that would limit the number of devices on that loop! I suppose if you were shooting for a single end device line, that would be ok.

24 volts for the loop is common where I come from.

:

Who knows what the Andy (the OP) had in mind.

4 to 20mA current loops are a pretty old industrial control standard, and 24 volts was a common supply voltage for such loops. Single rail rail systems are much more likely to run off a single +5V rail, and that choice makes the original problem tricky enough to be marginally interesting.

-- Bill Sloman, Nijmegen

--
You accuse me, without a shred of evidence, of doing what you admit
you\'re doing, then damn me while patting yourself on the back for doing
what you accuse me of.

Isn\'t that hypocritical?

Nobody, not even the superintelligent Sloman, could sell a 4-20 sourcing instrument with 5 volts of compliance capability.

A 250 ohm load is common in receiving instruments.

John