ADWSystems
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What's the second opamp for? Inverting 1:1 gain?
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What's the second opamp for? Inverting 1:1 gain?
That's news to me. Now you will have to go on the tangent and explain your train of thought.
Simple maths - for example if you multiply your result by 5 (to scale it) then the last digit can only be either 0 or 5. So it looks horribly messy, hence you truncate the last digit.
The same applies to all scaling factors, some are worse than others - get your calculator out and give it a try.
By doing the scaling in the attenuators, and using a final FSD reading of 102.3 (or any other variant of 1023), you get a perfect result.
Yes.What's the second opamp for? Inverting 1:1 gain?
It's either really early, or I'm still not following. Where is 102.3V coming from (other than 1/10th of 1023)? What relevance does it have on the 0-25V input signal?
I have never understood the reasonings put forth on ADC scaling to drop digits within the displayed value. I find it odd this topic only ever seems to come up on the forums. I have never had this discussion in the workplace or with any customers.
WHy do you keep mentioning 1%? Where does the 1% come from?
P.S. There are multibillion dollar companies that don't think 0 and 5 as LSD look horrible.
0=short or a piece of wire.Why 20k and 20k for the unity inverting opamp? Why not 0 and 0?
Oh. I haven't a problem with the last opamp. Even understand that it is gain -1. I thought there was an opamp configuration (inverting buffer) that did not have any resistors in the feedback loop.0=short or a piece of wire.
20k and 20k = gain of -1 in this case. (inverting) Not 1 but -1.
The first amp inverts the signal and the second one also inverts. -1 X -1 = 1
Use any two resistor of the same value. (ok not any...) but 200k or 100k or 51k.... It is a good idea to use the same parts all over the design.
Oops.You can get a gain of +1 with out resistors.
I used -5V.The voltage reference is -4.5V. Where I am I supposed to get that?
What does that stage do?Unfortunately, the offset is also needed in the third stage but adding instead of subtracting.
Sends control signal out to the control box of the lab equipment. I got scope locked worrying about the out-of-range reading signal from the equipment, I forgot about the control signal.What does that stage do?