Short, to the point, accurate and without any of those annoying YT bad habits (useless intro, catchphrases, shouting, unneeded pictures...) The gold standard of video tutorials.
Upto now i sam many of your videoes which were of very precise expaination of complex topics ,please share your knowledge as always and enlighten us ,thanks
Alan, the TI (ex-NatSemi) LMC6482 is my go-to for most applications. R-R IO, 2.7-15V supply, and decent general-purpose DC and AC specs. Main caveat is you need to be careful with capacitive loads, especially near unity gain, but careful design will mitigate most issues.
Excellent video. I didn’t exactly know what to expect in this video from the title, but this is actually something I was just thinking about attempting for adding a bar graph s meter to a radio. This has everything I need to work through the process. Thank you
This is one of the reasons I'm a subscriber- well done, fully informative (nothing left out), and to the point, concise, accurate. Just a _pleasure_ to learn from.
A feedback ratio of this video of 2.2K:6 ("I like this" : "I don't like this") says everything. Thank your for all of your educational videos. They helped me a lot, seriously. This channel is worth gold.
Thanks for another great learning experience. Your teaching skills are excellent, enough detail without repeating and a great pace. Thanks for all the help with the basics!
If anyone with low basic electronics knowledge listens with detail the way you explain your tutorials will enhance his knowledge so much... thank you..
Your explanation and demonstration is very good as always. The single supply op-amp amplifiers are often just taught assuming a sinusoidal input signal. It is recommended to use a decoupling capacitor to remove the DC offset prior to connecting the input signal to the amplifier and it is assumed that the op-amp will be used with an offset in the middle of the dynamic range (2.5V in this case). With your example you have shown that in real life things can be quite different from the general assumptions and you have shown a practical way to address it. Thanks!
I look forward to every video - the format of clear and concise problem definition ( the why ) , followed by the step by step explanation of what you need to understand regarding the building blocks of the solution , and then a worked example ( the how ) should be the standard template for all such videos . Hearty congrats ! I'm sure during your career you have mentored many . Like Feynman you have that rare talent , and ability to explain technical issues in a way that a layman can understand .
Just a thought: Trim pot wipers going directly into opamp inputs (7:45) - if the wiper should ever go intermittent the opamp will go crazy. It's best to link wiper to one of the ends and adjust resistance values accordingly. Keep safe, Beamer.
I've been doing this for years and not once had I considered a graphical method for calculating the offset. I always learn something from your videos! Re: input bias compensation, don't forget that matching the impedances seen by the inputs can have detrimental effects in opamps with internal bias cancellation. That, and the magnitude AND the sign of the bias current changes in CMOS and JFET inputs with temperature and input common mode voltage. Probably beyond the scope of this video, though.
Thanks Alan. As an absolute noob a few years ago, it took me quite a while to get my head around even the basic op amp idea. After that I struggled to find a non-audio simple use that would illustrate its use. This was perfect as I could see myself with a similar need, right down to using the extra as a buffer. I thought I was catching up to you after getting my Simpson 7M, now I have to find another one :) Dave
Was waiting to see if there was a "set SCE to AUX" comment in there, but none came. However a nice reminder that analogue electronics is still the thing that you need in a digital world, because all signals are after all at some point analogue, and even your digital is merely a very limited form at heart.
I agree in the comments about this being a very good video on the topic. For myself, in the learning phase still, I'd like to see more of a build-up process. Start with an inverting op amp and see what the output is, add the gain circuitry, add see what the output is, add the DC offset.... and so on. This for me would help ground me in what happens when, how and why, so that I could then know, when designing circuits, what I need to do. Maybe I'm not your target demographic... but I'm working on it! 🙂 Subscribed
So, that's what signal conditioning means!!! I don't know why I struggle so much with electronic concepts. It all seems so simple when you explain things, Alan. :-)
I think you could have mentioned sometimes op amps are useful when you need to drive something that requires more current than the source ( or sensor ) can deliver... having to use one for exactly that .. apart from that another perfect video and I really like the way you explain how to set the offset voltage.
That’s interesting. It was throwing me a bit at first. I was wondering how you had a positive input to an inverting amplifier but still had a positive output. I see you’re inverting the slope, so the negative going input voltage is “inverted” to a positive going output. I’ve never used that configuration before. I’ll have to play with that in SPICE. Nice solution.
Thanks Alan! Another great video, touching on an interesting point - adjusting offset voltage - and then work out such a simple signal conditioning solution. Really loved it :-)
Nice walkthrough! I would have approached it slightly differently, noting that op amps originated in the world of analog computers to do mathematical operations (hence the name). You're after a linear relationship, y = ax + b. With a little bit of algebra, substituting in the points you have on that line, ie. (2.5, 0) and (0.5, 5) out pops a = -2.5 (gain), b = 6.25 (offset). Then slot those into the op amp formula.
This appnote describes how to do that: www.ti.com/lit/an/sloa097/sloa097.pdf Both will work, I just took a more practical approach to it with less math.
@@w2aew omg, that is really terrifying! Yes you were more practical, no argument. They even list E96 series resistors as an appendix. But I may have to challenge you to an op amp shootout...
Great video! Love to see more like that. I'm not saying anything bad about all the others because they're really good as well but I like to see circuit solutions to applications.
One more thing you forgot to mention in the list of other considerations is the offset drift! It is great to be able to trim the circuit for precision, but if the measurement includes the weather, it is not a good measurement, unless designing a weather station, hihi :D //you could than also talk about about gain drift and TCR of the resistors, the input votlage/current noise and other stuff, but the offset drift may be still very important one for many applications//
True, but if offset drift is a worry you will not be using a MPC 600x part or a 741, but those have been specified as parts in those kind of applications. I should know, I changed enough 741's that had "excessive drift" in an application, used because when it was designed there literally was the 741, or even worse earlier opamps around. But that 741 can be pretty good, providing you run it at +-15V rails, and a good number were also fine running off +-22V rails, so the output swing could be 15V either side of 0V. Funny enough only those which were inputs were the unhappy ones, the output drivers were fine with only a clip on TO100 heatsink on them. Yes the stuff did have certifications, so 741 it was, never to change.
Yes, there are a lot of other factors like operation over temperature (drift), as well as taking into account component tolerances, power supply tolerances, etc. Most hobbyists don't get into these details, but they would certainly be part of a professional's design process.
Well, the MCP600x opamp is not as bad with its Vos drift. About 2uV/K, which may (or may not) be fine. Just wanted to point to this temperature dependence. Many of the hobbyists now using microcontrollers, measuring and digitally calibrating stuff. But mostly forgetting some of the important bottlenecks of such calibration, even trimming the stuff with pots. As not only the OPAMP itself has drift (probably order of magnitude lower) than the RF power sensor, that was mentioned in the vijeo :)
Alan, great video as always. Could I make a request for another curve tracer video? I’ve been interested in transistor leakage at zero base current. I have some no name 3906 transistors that appear to have considerably more leakage than one would expect for a silicon transistor. Anyway I was wondering if you could do a more in depth video about curve tracing techniques. Thanks!
Thanks for walking us through the steps on this design! Could this be useful in the context of audio applications to bring an analog microphone signal to span a paticular voltage range prior to ADC encoding? I imagine some other preconditioning would be important, such as preventing the signal from being at too extreme an input level. I'm still learning circuit design and electronics, coming from a background in software development, and your entire channel has been very helpful!
:) I'm so happy! I understood everything you said in this video. I wouldn't be able to come up with such a solution myself - yet, but hopefully in the future. Thanks for this splendid video. Just what I need :)
Bill-N6EF-Thanks for a great explanation. Very informative. When I want to design something in general, I don't know which components to use since there are so many choices. How did you know to use that specific op-amp for this application? Experience with that series of devices?
Usually it comes down to the constraints and requirements for the circuit. Things like: Supply Voltage available, voltage range of input and output, speed/bandwidth required, power consumption, noise, etc. Sometimes it is only one or two of these constraints or requirements that will determine which type/family of op amp to use. Many times there will be a large variety of op amps that will fit the bill, and the choice may come down to availability, cost, etc., or even what stock you have on hand. Unfortunately, there is no simple answer. In this case, I had constraints of a single 5V supply and the need for a 0 to 5V output - so I needed a single supply op amp with rail-rail output. Those were the major constraints - then I looked at what I had on hand.
Great video, it's always worth watching your videos. By the way wouldn't be more stiff design if a cap is hooked up to R4 in parallel? This's what I thought of first.
I did it ! Mine has a gain of 1.74 with an input voltage of 2.8, R1 = 1K, R2 = 1740, V offset around 1.9. My power supply is 5V from an arduino so i kept the values small but it seemed to work on my scope. Drops to around 1 volt when i push a tactile for the input.
Very interesting! I try to fit those numbers into the linear equation and I got a transfer function y = -2.5*x +6.25, where x is the output from the sensor and y is the expected output from the circuit. I guess you can build a circuit to realize this but why it's different from what you mentioned? Your circuit seems much simpler.
This appnote describes how to do that: www.ti.com/lit/an/sloa097/sloa097.pdf Both will work, I just took a more practical approach to it with less math.
Neither of those have rail-rail outputs - so they will work *only* if the supply voltage exceeds the required output swing. You have to consult the datasheets to see how much headroom is needed between the supply rails and the min/max output voltage needed.
When looking at the Op amps datasheets it specs about the Input Biasing current is in the microamps from input#1 and input#2. What does this mean because the larger the input biasing current the worse the Op amp can be comparing inputs or differentiators and comparator circuits?
This is a great video, but I was so sure the offset voltage was going to be 6.25V, because if you multiply the full range by the gain then add that offset, you get the correct output from the problem. While I understand how you calculated the 1.78 offset, I don't quite feel like I have the full picture, so I would have liked if you had shown the formula of the amplifier gain which included the offset in the equation.
Then you have to split the circuit in two parts. One part with only the input voltage and the second part with only the offset voltage. With the superposition theorem and some calculations you can determine the offset voltage. I can send you a copy of that calculation but I don't see an link or something else to do so.
Would it be possible to make this in the non-inverting variety other then using a second op-amp as a unity gain inverter. I have a signal coming from a LM35 temp sensor that starts from 0.25v and goes to 0.75v and I need to condition it to 0 - 5v. Thanks
Sure, you could do this with a non-inverting configuration without the need for an inverter. You just need an overall non-inverting gain of +10 with an appropriate offset summed in.
Thanks. Q. How do you measure sensor output impedance ? is it on the datasheet? I saw this term for uControllers too, but I have never seen any number or way to measure an IC pin impedance. Thanks again
Usually on the datasheet. If not, then there's usually some information about how much of a load the output can drive, or how much current the output can deliver to a load. These will give you some insight into the output impedance.
Hi Alan, I have a tricky op amp circuit request. I have not found a single attempt at this solution anywhere on the web, or in text books. Say my signal is a 150mV AC signal at 2Hz on a +3VDC bias. I would like to separate my signal into its AC and DC components. The only way I can sort of achieve it is to 'average' the AC using a high value R and C to ground and take an 'average' at the mid point. Then use an adder in subtract configuration to remove it from the original signal. Not very clean, due to the very low frequency AC component remaining in the 'average' signal. The R is about 10Meg and the C is 10u. Does this question make sense? Thank you for your wonderful videos and very best regards,
Hi. Could you please elaborate a bit more on how you got to an input offset voltage of 1.78V? I was expecting it to be 2.5V since that would have brought the op-amp output to 0V for 2.5V input to the inverting terminal.
If the offset was 2.5V, and the input was 2.5V, that would imply that there is zero current in R1, which means that there would be zero current in R2, and the output would have to be at 2.5V also. The key to understanding this is that the inverting input of the op amp draws virtually no current.
@@w2aew You're right. I don't know in what world I was; I got it confused with a differential amplifier. Thank you for responding though. In hindsight, if I'm not wrong, one could use a differential amplifier too to achieve the same purpose, can't they?
Some op amps use emitter followers or source followers on the inputs such that the input common mode range can extend slightly beyond the supply rails.
More generally, if the power supply is not 5V or if it is susceptible to changing, you can use a biased Zener diode as the reference to the positive voltage divider.
Awesome video - and the perfect use for some analog meters. I'd love to pick up some just for such an occasion. Hmmmm....Any recommendations that don't break the bank, and are not 60 years old?
The 260 Series 8 is still being produced, but pretty pricey if purchased new. There are some inexpensive ones still available new: www.amazon.com/analog-multimeter/s?k=analog+multimeter
This was great. Thanx. What are practical uses for integrator and differentiator op amp circuits? Besides square to triangle or triangle wave to square wave generators.
There are a variety of filtering applications where they could be useful. I've used integrators to generate the average voltage of a signal, and I've used differentiators to produce short pulses at the edges of square waves and PWM signals.
Ok, a pedantic question from an engineering technician. Other than the two in a package why did you choose the MCP6002 over the National (now TI) LMC6001? I can see from the TI pages that the LM6001 (national), the TLV6002 (?) and the MCP 6002 are all slightly different but are very close. E.g. GBP LMC=1.3Mhz, TLV=1Mhz, MCP=1Mhz, Slew(typ) LMC=1.5, TLV=0.5, MCP=0.6 the noise figures are different, etc. The LMC lists the input bias current at 1000fA as a maximum where the TLV and MCP list that as a 'typical' unit. I suspect this is the same "design" and the differences are so small that except for corner cases I can see them being interchangeable with each other from an engineering standpoint. Now that's with only looking at data sheets for 30 min.
Why did I choose the MCP6002 over the LMC6001? Two reasons - 1) I needed another stage to buffer my 'sensor simulator', and 2) it's what I had in my personal stock. Plus, the MCP part is a lot cheaper.
If the 1.78V wasn't applied to the op amp input, the output would always stay pinned at the lower rail, because the input voltage applied to the inverting-input would always be higher than the voltage at the non-inverting input.
@@HalfLife2Beta For an inverting op amp with 0V on the non-inverting input, it converts a 0 to X voltage to a 0 to -Y voltage. Use a non-inverting configuration if you want 0 to X ---> 0 to Y. We wanted an inverting config here to make the trend go in the opposite direction.
There are a few options for the reverse banana probes. I show them in this video: ruclips.net/video/tfmRzkU_Y6g/видео.html These are the ones I'm using: www.amazon.com/gp/product/B07SSZVZLT Note that you will likely have to slightly distort (squeeze) the barrel a little as I show in the above video.
@@w2aew Thanks. I picked up a series 8 meter and I remember the probemaster recommendation. I have several sets of their probes and I like them a lot but these didn't fit property on my meter. They sent me a second pair to try and the contacts on both were too small in diameter and became deformed (★★★★★ support.) I also ordered some Oldaker 486-3 leads on ebay and those are a bit loose but work... OK.
Yes, of course. In this case, you want a voltage gain of (4-1)/(1.09-0.63) = 8.696. And, if you've described the relationship right, you want it to be non-inverting. So, you'd choose a non-inverting op amp configuration. You can use a "summing amplifier" type of design to add in an appropriate offset to get the output offset adjusted correctly.
A shunt regulator using - a resistor and a pair of diodes in series, - or with a "Vbe multiplier" Or, use a three terminal regulator like a LM317 with the appropriate scaling resistors.
Short, to the point, accurate and without any of those annoying YT bad habits (useless intro, catchphrases, shouting, unneeded pictures...)
The gold standard of video tutorials.
can't agree more
Excellent Presentation skills!
hah hah.. the shouting extends waaaay beyond RUclips.
Absolutely but you missed out waving his arms incessantly and shouting HEY GUYS WHAT IS GOING ON!
...(or incessant repetition or lengthy asides to promote one’s own products.)
Upto now i sam many of your videoes which were of very precise expaination of complex topics ,please share your knowledge as always and enlighten us ,thanks
And that, dear students, is a great example of exactly how good electronics engineers should always approach their opamp design work!
MCP600x is a very underrated series
its alive. thanks for your videos. those really made electronics and starting uni semester easy.
Agree- a lot of near-enough-to-ideal characteristics. What's your recommendation for something similar but will work up to 15V supply?
Microchip does such a good job on so many of its products.
the cont has awakened from his slumber...
Alan, the TI (ex-NatSemi) LMC6482 is my go-to for most applications. R-R IO, 2.7-15V supply, and decent general-purpose DC and AC specs. Main caveat is you need to be careful with capacitive loads, especially near unity gain, but careful design will mitigate most issues.
That was really intuitive video on op amp with clear explanation, really thanks a lot for this video sir
Excellent video. I didn’t exactly know what to expect in this video from the title, but this is actually something I was just thinking about attempting for adding a bar graph s meter to a radio. This has everything I need to work through the process.
Thank you
This is one of the reasons I'm a subscriber- well done, fully informative (nothing left out), and to the point, concise, accurate. Just a _pleasure_ to learn from.
Absolutely.
A feedback ratio of this video of 2.2K:6 ("I like this" : "I don't like this") says everything. Thank your for all of your educational videos. They helped me a lot, seriously. This channel is worth gold.
Never have I seen a clearer explanation of opamp signal conditioning -- bookmarked for next time I forget everything :). Thank you.
Thanks for another great learning experience. Your teaching skills are excellent, enough detail without repeating and a great pace. Thanks for all the help with the basics!
If anyone with low basic electronics knowledge listens with detail the way you explain your tutorials will enhance his knowledge so much... thank you..
Your explanation and demonstration is very good as always.
The single supply op-amp amplifiers are often just taught assuming a sinusoidal input signal.
It is recommended to use a decoupling capacitor to remove the DC offset prior to connecting the input signal to the amplifier and it is assumed that the op-amp will be used with an offset in the middle of the dynamic range (2.5V in this case).
With your example you have shown that in real life things can be quite different from the general assumptions and you have shown a practical way to address it.
Thanks!
Putting this one in my Favorites folder for reference!
I look forward to every video - the format of clear and concise problem definition ( the why ) , followed by the step by step explanation of what you need to understand regarding the building blocks of the solution , and then a worked example ( the how ) should be the standard template for all such videos . Hearty congrats ! I'm sure during your career you have mentored many . Like Feynman you have that rare talent , and ability to explain technical issues in a way that a layman can understand .
Just a thought: Trim pot wipers going directly into opamp inputs (7:45) - if the wiper should ever go intermittent the opamp will go crazy. It's best to link wiper to one of the ends and adjust resistance values accordingly. Keep safe, Beamer.
Yes, that's always a good idea.
I've been doing this for years and not once had I considered a graphical method for calculating the offset. I always learn something from your videos!
Re: input bias compensation, don't forget that matching the impedances seen by the inputs can have detrimental effects in opamps with internal bias cancellation. That, and the magnitude AND the sign of the bias current changes in CMOS and JFET inputs with temperature and input common mode voltage. Probably beyond the scope of this video, though.
Yeah, a little beyond the scope of this video - but all good points.
Serendipity strikes again. Just when I needed advice on optimizing input and offset values, this program popped up. Thank you and 73, Alan.
Thanks Alan. As an absolute noob a few years ago, it took me quite a while to get my head around even the basic op amp idea. After that I struggled to find a non-audio simple use that would illustrate its use. This was perfect as I could see myself with a similar need, right down to using the extra as a buffer. I thought I was catching up to you after getting my Simpson 7M, now I have to find another one :) Dave
I was just scratching my head trying to solve the exact same problem and this solution fits perfectly in my project, thank you!
very nice video. Another final tought: always limit the bandwith of an opamp circuit. you will get less noise and more stability.
Yes, good tip!
Clear and very good explanation of circuits. I see things that most theory books don't explain or fail to get the info across. Subscribed and liked.
Was waiting to see if there was a "set SCE to AUX" comment in there, but none came. However a nice reminder that analogue electronics is still the thing that you need in a digital world, because all signals are after all at some point analogue, and even your digital is merely a very limited form at heart.
I agree in the comments about this being a very good video on the topic. For myself, in the learning phase still, I'd like to see more of a build-up process. Start with an inverting op amp and see what the output is, add the gain circuitry, add see what the output is, add the DC offset.... and so on. This for me would help ground me in what happens when, how and why, so that I could then know, when designing circuits, what I need to do. Maybe I'm not your target demographic... but I'm working on it! 🙂
Subscribed
I enjoy the way you explain exactly how your circuits work with the maths ,always helpful, its nice to watch a professional at work. 73 Paul de M0BSW
That is perhaps the most elegant solution imaginable. Thanks!
Excellent video as always, thank you so much for the link to the paperwork download, I just wish more people did that!
Интересные старинные измерительные приборы.
Interesting old measuring instruments.
So, that's what signal conditioning means!!!
I don't know why I struggle so much with electronic concepts. It all seems so simple when you explain things, Alan. :-)
Lovely! If education material and university courses could be just half as good as your explanations :)
Good project to showcase the principles and versatility of simple OpAmp circuits!
A very well put together and explained example. One of the best I've seen in 30 years!
Nice video. Great as a quick refresher when studying electronics. I haven't thought about it graphically before.
I think you could have mentioned sometimes op amps are useful when you need to drive something that requires more current than the source ( or sensor ) can deliver... having to use one for exactly that .. apart from that another perfect video and I really like the way you explain how to set the offset voltage.
Good point - I "sort of" hinted at that with my sensor simulator being buffered with the unity gain stage.
That’s interesting. It was throwing me a bit at first. I was wondering how you had a positive input to an inverting amplifier but still had a positive output. I see you’re inverting the slope, so the negative going input voltage is “inverted” to a positive going output. I’ve never used that configuration before. I’ll have to play with that in SPICE. Nice solution.
I will never grow tired of op amps and I will never grow tired of these fantastic videos. Thank you for doing what you do, sir :-)
Hallo Bang Admin yang baik hati,
This video is very useful. We can understand the information clearly. Thank you.
Nice. A practical, real world example that you may come across. 👍
Thanks Alan! Another great video, touching on an interesting point - adjusting offset voltage - and then work out such a simple signal conditioning solution. Really loved it :-)
Input bias currents and compensation resistance should be taken into consideration
@@aqib2000 You didn't watch to the end, did you...
You are an invaluable asset to newbies. Another awesome video. I appreciate your efforts!
Nice walkthrough! I would have approached it slightly differently, noting that op amps originated in the world of analog computers to do mathematical operations (hence the name). You're after a linear relationship, y = ax + b. With a little bit of algebra, substituting in the points you have on that line, ie. (2.5, 0) and (0.5, 5) out pops a = -2.5 (gain), b = 6.25 (offset). Then slot those into the op amp formula.
This appnote describes how to do that: www.ti.com/lit/an/sloa097/sloa097.pdf
Both will work, I just took a more practical approach to it with less math.
@@w2aew omg, that is really terrifying! Yes you were more practical, no argument. They even list E96 series resistors as an appendix. But I may have to challenge you to an op amp shootout...
Thanks a lot for the video. Еvery time I watching a new video from you I'm upgrading something in myself.
Great video! Love to see more like that. I'm not saying anything bad about all the others because they're really good as well but I like to see circuit solutions to applications.
What a gfreat excuse to use the Simpson meters! :)
I spent countless hours TI's circuit simulator designing the same type of circuit for a Pirani Vacuum gauge that you spent 15 minutes on here LOL!
All your videos are amazing. Am a long time subscriber of yours. Really love to see those beefy analog meters everytime.
One more thing you forgot to mention in the list of other considerations is the offset drift! It is great to be able to trim the circuit for precision, but if the measurement includes the weather, it is not a good measurement, unless designing a weather station, hihi :D
//you could than also talk about about gain drift and TCR of the resistors, the input votlage/current noise and other stuff, but the offset drift may be still very important one for many applications//
True, but if offset drift is a worry you will not be using a MPC 600x part or a 741, but those have been specified as parts in those kind of applications. I should know, I changed enough 741's that had "excessive drift" in an application, used because when it was designed there literally was the 741, or even worse earlier opamps around. But that 741 can be pretty good, providing you run it at +-15V rails, and a good number were also fine running off +-22V rails, so the output swing could be 15V either side of 0V. Funny enough only those which were inputs were the unhappy ones, the output drivers were fine with only a clip on TO100 heatsink on them. Yes the stuff did have certifications, so 741 it was, never to change.
Yes, there are a lot of other factors like operation over temperature (drift), as well as taking into account component tolerances, power supply tolerances, etc. Most hobbyists don't get into these details, but they would certainly be part of a professional's design process.
Well, the MCP600x opamp is not as bad with its Vos drift. About 2uV/K, which may (or may not) be fine. Just wanted to point to this temperature dependence. Many of the hobbyists now using microcontrollers, measuring and digitally calibrating stuff. But mostly forgetting some of the important bottlenecks of such calibration, even trimming the stuff with pots. As not only the OPAMP itself has drift (probably order of magnitude lower) than the RF power sensor, that was mentioned in the vijeo :)
Excellent video. I love videos. About opamps. Waiting on super small input voltages into opamps projects from you.
Alan, great video as always. Could I make a request for another curve tracer video? I’ve been interested in transistor leakage at zero base current. I have some no name 3906 transistors that appear to have considerably more leakage than one would expect for a silicon transistor. Anyway I was wondering if you could do a more in depth video about curve tracing techniques. Thanks!
Thanks for walking us through the steps on this design! Could this be useful in the context of audio applications to bring an analog microphone signal to span a paticular voltage range prior to ADC encoding? I imagine some other preconditioning would be important, such as preventing the signal from being at too extreme an input level. I'm still learning circuit design and electronics, coming from a background in software development, and your entire channel has been very helpful!
Yes, it certainly could be used to adjust the amplitude and offset of an audio signal.
Nice work, Alan. Thanks.
Excellent as usual ... with downloadable notes!!! Thanks
:) I'm so happy! I understood everything you said in this video. I wouldn't be able to come up with such a solution myself - yet, but hopefully in the future.
Thanks for this splendid video. Just what I need :)
Bill-N6EF-Thanks for a great explanation. Very informative. When I want to design something in general, I don't know which components to use since there are so many choices. How did you know to use that specific op-amp for this application? Experience with that series of devices?
Usually it comes down to the constraints and requirements for the circuit. Things like: Supply Voltage available, voltage range of input and output, speed/bandwidth required, power consumption, noise, etc. Sometimes it is only one or two of these constraints or requirements that will determine which type/family of op amp to use. Many times there will be a large variety of op amps that will fit the bill, and the choice may come down to availability, cost, etc., or even what stock you have on hand. Unfortunately, there is no simple answer. In this case, I had constraints of a single 5V supply and the need for a 0 to 5V output - so I needed a single supply op amp with rail-rail output. Those were the major constraints - then I looked at what I had on hand.
Great video, it's always worth watching your videos. By the way wouldn't be more stiff design if a cap is hooked up to R4 in parallel? This's what I thought of first.
Yes, that couldn't hurt as well.
I did it ! Mine has a gain of 1.74 with an input voltage of 2.8, R1 = 1K, R2 = 1740, V offset around 1.9. My power supply is 5V from an arduino so i kept the values small but it seemed to work on my scope. Drops to around 1 volt when i push a tactile for the input.
Very interesting! I try to fit those numbers into the linear equation and I got a transfer function y = -2.5*x +6.25, where x is the output from the sensor and y is the expected output from the circuit. I guess you can build a circuit to realize this but why it's different from what you mentioned? Your circuit seems much simpler.
This appnote describes how to do that: www.ti.com/lit/an/sloa097/sloa097.pdf
Both will work, I just took a more practical approach to it with less math.
Ha! This is actually relevant to a kludge of mine. Good timing!
Wonderful instruction, well done and thanks.
Thanks for sharing.
Does common 4558/TL072 works on these setups?
Neither of those have rail-rail outputs - so they will work *only* if the supply voltage exceeds the required output swing. You have to consult the datasheets to see how much headroom is needed between the supply rails and the min/max output voltage needed.
@@w2aew Thanks for quick reply and clear explanation.
When looking at the Op amps datasheets it specs about the Input Biasing current is in the microamps from input#1 and input#2. What does this mean because the larger the input biasing current the worse the Op amp can be comparing inputs or differentiators and comparator circuits?
How is the latency in this circuit? Was thinking about the use case as a level shifter for data signals.
All you need to do is use an op amp with more bandwidth, although there are probably better ways to level shift data signals.
Wow. So simple. Great tutorial.
This is a great video, but I was so sure the offset voltage was going to be 6.25V, because if you multiply the full range by the gain then add that offset, you get the correct output from the problem. While I understand how you calculated the 1.78 offset, I don't quite feel like I have the full picture, so I would have liked if you had shown the formula of the amplifier gain which included the offset in the equation.
Then you have to split the circuit in two parts. One part with only the input voltage and the second part with only the offset voltage. With the superposition theorem and some calculations you can determine the offset voltage. I can send you a copy of that calculation but I don't see an link or something else to do so.
Excellent tutorial, dude.
More of such please !!
Would it be possible to make this in the non-inverting variety other then using a second op-amp as a unity gain inverter.
I have a signal coming from a LM35 temp sensor that starts from 0.25v and goes to 0.75v and I need to condition it to 0 - 5v.
Thanks
Sure, you could do this with a non-inverting configuration without the need for an inverter. You just need an overall non-inverting gain of +10 with an appropriate offset summed in.
@@w2aew Thanks.!!!
Tony. KE8SPI
Really really great video! Very informative and clear. Thank you,sir!
Outstanding quality content. Very much appreciated :)
Thanks. Q. How do you measure sensor output impedance ? is it on the datasheet? I saw this term for uControllers too, but I have never seen any number or way to measure an IC pin impedance. Thanks again
Yes. Always consult the datasheet.
Usually on the datasheet. If not, then there's usually some information about how much of a load the output can drive, or how much current the output can deliver to a load. These will give you some insight into the output impedance.
A nice example of analog signal conditioning.
Looking forward to more op-amp fun... maybe a brain twisting delve into gyrators? :D
Cheers,
That was beautifully done👏👏
Very nice vintage multimeters!
Hi Alan, I have a tricky op amp circuit request. I have not found a single attempt at this solution anywhere on the web, or in text books. Say my signal is a 150mV AC signal at 2Hz on a +3VDC bias. I would like to separate my signal into its AC and DC components. The only way I can sort of achieve it is to 'average' the AC using a high value R and C to ground and take an 'average' at the mid point. Then use an adder in subtract configuration to remove it from the original signal. Not very clean, due to the very low frequency AC component remaining in the 'average' signal. The R is about 10Meg and the C is 10u.
Does this question make sense?
Thank you for your wonderful videos and very best regards,
Hi. Could you please elaborate a bit more on how you got to an input offset voltage of 1.78V? I was expecting it to be 2.5V since that would have brought the op-amp output to 0V for 2.5V input to the inverting terminal.
If the offset was 2.5V, and the input was 2.5V, that would imply that there is zero current in R1, which means that there would be zero current in R2, and the output would have to be at 2.5V also. The key to understanding this is that the inverting input of the op amp draws virtually no current.
@@w2aew You're right. I don't know in what world I was; I got it confused with a differential amplifier. Thank you for responding though. In hindsight, if I'm not wrong, one could use a differential amplifier too to achieve the same purpose, can't they?
Can you help to explain further on Common Mode and why some chips can handle voltages higher than their supply voltages
Some op amps use emitter followers or source followers on the inputs such that the input common mode range can extend slightly beyond the supply rails.
could u make a video about junction fet drain detector?
also how is it possible to design a jfet circuit where its biased at cutoff?
More generally, if the power supply is not 5V or if it is susceptible to changing, you can use a biased Zener diode as the reference to the positive voltage divider.
lovely! always enjoy these.
Awesome video - and the perfect use for some analog meters. I'd love to pick up some just for such an occasion. Hmmmm....Any recommendations that don't break the bank, and are not 60 years old?
The 260 Series 8 is still being produced, but pretty pricey if purchased new. There are some inexpensive ones still available new: www.amazon.com/analog-multimeter/s?k=analog+multimeter
Beautifully done as always :)
Great explanation. Fun stuff.
Two Simpsons - grassroots electronics, I like it! Useful stuff as always, welcome back :-)
I want oldschool meters like those- are they still manufactured?
This was great. Thanx. What are practical uses for integrator and differentiator op amp circuits? Besides square to triangle or triangle wave to square wave generators.
There are a variety of filtering applications where they could be useful. I've used integrators to generate the average voltage of a signal, and I've used differentiators to produce short pulses at the edges of square waves and PWM signals.
@@w2aew OHH!!! OK Makes sense. Thanx.
beautiful tutorial
This guy knows his Shi&! You should be a university professor
Very very useful tutorial. Thanks very much.
Very enjoyable video!
Ok, a pedantic question from an engineering technician. Other than the two in a package why did you choose the MCP6002 over the National (now TI) LMC6001? I can see from the TI pages that the LM6001 (national), the TLV6002 (?) and the MCP 6002 are all slightly different but are very close. E.g. GBP LMC=1.3Mhz, TLV=1Mhz, MCP=1Mhz, Slew(typ) LMC=1.5, TLV=0.5, MCP=0.6 the noise figures are different, etc. The LMC lists the input bias current at 1000fA as a maximum where the TLV and MCP list that as a 'typical' unit. I suspect this is the same "design" and the differences are so small that except for corner cases I can see them being interchangeable with each other from an engineering standpoint. Now that's with only looking at data sheets for 30 min.
Why did I choose the MCP6002 over the LMC6001? Two reasons - 1) I needed another stage to buffer my 'sensor simulator', and 2) it's what I had in my personal stock. Plus, the MCP part is a lot cheaper.
Can u explain what would happen without the offset voltage created by the voltage divided please? I didnt quite get that.
If the 1.78V wasn't applied to the op amp input, the output would always stay pinned at the lower rail, because the input voltage applied to the inverting-input would always be higher than the voltage at the non-inverting input.
@@w2aew thanks so it means it would only work for converting for e.g. 0 to X V input to 0 to Y V output ?
@@HalfLife2Beta For an inverting op amp with 0V on the non-inverting input, it converts a 0 to X voltage to a 0 to -Y voltage. Use a non-inverting configuration if you want 0 to X ---> 0 to Y. We wanted an inverting config here to make the trend go in the opposite direction.
@@w2aew thanks its so clear now
What are those late series Simpson banana jack adapters you're using?
There are a few options for the reverse banana probes. I show them in this video: ruclips.net/video/tfmRzkU_Y6g/видео.html
These are the ones I'm using: www.amazon.com/gp/product/B07SSZVZLT
Note that you will likely have to slightly distort (squeeze) the barrel a little as I show in the above video.
@@w2aew Thanks. I picked up a series 8 meter and I remember the probemaster recommendation. I have several sets of their probes and I like them a lot but these didn't fit property on my meter. They sent me a second pair to try and the contacts on both were too small in diameter and became deformed (★★★★★ support.) I also ordered some Oldaker 486-3 leads on ebay and those are a bit loose but work... OK.
Very well done. Thanks.
Hello, i have a question.. if i have input values ranging from 0.63 to 1.09V and i want corresponding output values of 1-5V ... is this possible?
Yes, of course. In this case, you want a voltage gain of (4-1)/(1.09-0.63) = 8.696. And, if you've described the relationship right, you want it to be non-inverting. So, you'd choose a non-inverting op amp configuration. You can use a "summing amplifier" type of design to add in an appropriate offset to get the output offset adjusted correctly.
@@w2aew 🙏thank you! Seems like a pain in the butt
@@ohmslaw6856 Not really, just your basic, very common, op amp design process.
@@w2aew doesn't help I'm some what of a dumb@ss haha.. im just struggling with the offset..
@@w2aew i finally got it! Thank you again for your time
What be the best/easiest way to convert a 3.0 volt(or other voltage) wall charger to power a 1.5 volt AA wall clock? Thanks in advance
A shunt regulator using
- a resistor and a pair of diodes in series,
- or with a "Vbe multiplier"
Or, use a three terminal regulator like a LM317 with the appropriate scaling resistors.
I thought you will use an arduino and map the output but this is much cheaper and tons of fun
fantastic as always.
Hi Alan, always great videos. Can you make a similar one but with non rail-rail opamps. Thanks.
Trivial - simply use power supply rails that are sufficiently far away from the input/output voltage extremes.
@@w2aew thanks
Another kind of signal conditioning is the conversion of a 0 to 10 V input signal to a 4 to 20 mA output signal or the other way around.
Thank you sir for the tutorial.
Great tutorial.
Helpful video 👍