What a rarity! A TH-cam video by someone who really knows his electronics theory, clearly explaining what he's showing, and with good audio at a reasonable level. Excellent! :)
I'm enjoying your videos, thanks. Another easy measure on the scope is, 0.707 x 7 units = 5 units, useful for 3db points. Actual 4.949, closer than I can see! Edit: Reading my mail 2 years late, to describe how I do this a little better, I set the Volt/Div so the signal is more than 7 units and then adjust the variable knob for 7 units, then I make any external circuit adjustments until the signal drops to 5 units, this is the 3db point.
One never gets around to doing back to basics but you have inspired me to do so. Your videos are so enthusing and fun. Keep up the good work. You are an excellent teacher.
Some of the most clear, to the point and instructional videos I've seen! Wow, keep up the good work! A joy to watch and an effective way to learn some basics.
I have to say, I think I've seen most you videos maybe even twice. I really appreciate the effort you've placed with all this content. I accidentally found your channel looking for ESR measurements with oscilloscopes and saw that you have a plethora of info on radio stuff as well. Well I could go on and on... In short, I have to say thank you very much for giving us all these invaluable lessons!
I've had the money set aside to buy my first real scope and I've been researching and humming and hawing over this for some time. Watching this finally pushed me over the edge and I made my decision. Just bought a Hantek DSO5202P from Amazon. It has almost everything I wanted, except integration and differentiation. But as it is, this one as $470, which is about $150 more than I planned to spend. I decided it was worth the extra money for a 2 channel scope vs 1 channel. I get the feeling the extra channel will be worth it. My only regret is doing this at 5am when I haven't slept yet. I'm far too excited to sleep now. Listen to me gushing like a school girl with a crush. =D Now for my next dilema, buying a function generator.
Great bench technique to pass along to our younger players, & led me back to your "Fast Edge Pulser / TDR" one; which videos earned my subscription. Nostalgia for the many fast pulse edges & TDR work in my misspent youth!
Reminds me of the electronics training I received in the US Army (circa 1991), straight and to the point highly effective knowledge transfer! Thank You!
Thank you. There's loads of "what is an oscilloscope?" videos and loads of TY2603L-Mega reviews, but not so many "things to do with one" vids. Really liking your other vids too.
You want to measure frequently at the zero crossings. It is hard to tell the peak, but the zero crossings are well defined. Also, it is more accurate to make the zero crossings as far apart on the CRT as possible either by adjusting the horizon sweep time or measure the time between a number of crossings and divide accordingly. It goes without saying that these zero crossings should all be the high to low or low too high crossings. Distortions in the wave can make your frequently measurement inaccurate if you measure half cycle times. Excellent video and I love your test fixtures.
Great explanation. Uses a mathod I've never tried before. 👍 One thing that I've noticed is that just about everyone makes the assumption that their viewers already know what units of measurement the formulas will be using when they do the math. But that average neophyte electronics student doesn't know that all the calculations answers will be in units of farads and henrys, or even in ohms. They most likely assume that the units will be in microfarads microhenrys and kilohms. So these units really need to be explicitly stated. Thanks for this useful video.
Thanks for a great treatment of my scope junction blog! Nice setup; when I do this I just slap-solder the parts together in the air. One point needs comment - for very small capacitors one needs to measure the capacitance of the fixture and the 10:1 scope probe first with the same technique so the probe and fixture capacitance can then be subtracted from the final measured value when the cap under test is added to the RC circuit. The LC circuit is also known as a "tanktwanger" since the effect is so similar to twanging a guitar string.
You used the rise time measurement for "C", and used the frequency measurement for knowing "L". We can as well use the frequency measurement for determining the "C" as well, when we have a known value of "L". Very resourceful video indeed.
Thank you for a very informative video and presentation of techniques. I liked it and the best thing was the quality of video and crystal clear voice; rather commentary. You are a good teacher. Thank you.
Using 74HC14 (as opposed to 74AC14), I'm getting 5ns rise time with 100nF + 3k3 RC. The squarewave runs at about 5kHz. The rise time seems to be pretty much independent of supply voltage between 2.5V through to 6V. I'm going to try packaging into an Altoids tin with 2xAA Alkaline => 3V supply. Mine's a Texas Instruments manufactured chip. I measured the rise time on my Owon DS7102V 100MHz Chinese scope. Compare this to the 350ns coming out of the scope's own 1kHz square wave probe calibration pins. 74HC14's are super-cheap and readily available in DIP on eBay. Thanks for a great circuit tip! EA5IGC
I really appreciate your very hands-on review of basics! Quite useful. But, I imagine there is some limit to the range of capacitance if your input waveform is set at 5-6KHz.
The capacitance measurement is made by looking at the risetime of the signal (the RC time constant), so the frequency of the signal really doesn't enter into it, as long as it is low enough to permit the RC circuit to fully settle before the next half cycle.
Great video. One of the best that I have seen. Now I can measure the C 's that I have to see if the value is as marked, the same for the L's I have. Since I am a retired EE I like to know the value as to how close the value as marked. I suggest that the value for measuring C's I would make the resistor 1% or better. The same applies for the C's to measuring the value L.
Great lab. What you just demo are is one of the first lab students perform in ac circuits courses. Brings back memories. You shot title your videos engineering lab ;)
Thank you for explaining this in so little time. It really takes a lot of skill!!! I'm watching your video for the first time, and I will definitely try to build the pulse generator. :)
Thanks for clear instruction and demonstration of this measurement. I was lucky to find a 2467 in January. I need to study the manual better. Very nice functionality.
well i found out my function generator uses the max038 chip witch the data sheets said square wave rise and fall for both are 12ns so i guess your circuit would work so i will build it thank you for your help in answering my questions even i majored in electronics in high school i forgot some and guess some things didnt stick because i must not of fully understood either but with your teaching i see it in a whole different light thank you again
Thank you for showing this. I've been trying to measure inductance with my scope for some time now, but I could never figure out how to do it correctly.
you seem to be very knowledgeable both about fully utilizing your very capable scope and combining that with known formulas. Might I ask if you have a video that would show a person who has both a speaker, an audio amplifier, a frequency generator and a (lesser capable) scope than yours - how they would measure the 'free air impedance' of a speaker transducer at a desired frequency?
Great video!!! Do you know how to measure the inductance "online"? This is when it is loaded, i.e. current flows through it and in the same time the inductance changes (ex. the core varies)? It's difficult but can be extremely useful.
Alan, Thank you very much for the quick answer. I will really appreciate if you can share some quick tips meanwhile video is on the way. Congratulations for your Amazing job and to share all this tips.
With your ground free battery operated steep egde pulse generator you can use also the same circuit for the inductor as for the capacitor. It is not necessary to build up a resonator. Also the error is increasing because its much easier to get a tightly tolerated resistor than such capacitor. In the inductor case you just need to clamp your oscilloscope aross the terminals of the resistor to observe the voltage rising, which represents the current rising across the inductor. The math behind is the same.
At first glance, it seems to work with calibration output of the scope, although there might be some limitations. For example, on my scope, the rising edge of that signal is about 3.5us, therefore if we estimate that the rising time is the required time to go from the 10% up to the 90% of the signal amplitude, that would be about 2.197 times tau. Under those circumstances, if we want to see the complete signal, from 0 to 5 tau, with a 1k resistor, I would be able to estimate the capacitors values from about 1.33nF and up. Overall, there is always a way, but we need to experiment and do some homework to understand what is happening.
Very interesting. One guy I worked with liked to test diodes with a low voltage 60 Hz signal. He would look at the response with his VOM, I think. I prefer to just measure the resistance both ways with an analog VOM, on the 1k or 10k scale.
One caution - the capacitor used for inductance measurement must be a high quality dielectric with minimum losses. ie, don't use a capacitor purchased from a Chinese supply chain source. A couple days ago one of my colleagues tried this to test a transformer winding and could not get it to ring. After looking over his setup, I suggested he use a capacitor from my junkbox, not that brown ceramic disc of dubious origin. It turned out that was exactly the problem.
Your videos are very informative. Just got me a free scope (70s Siemens Oscillar) and your videos are a great help getting started with it. subscribed ;)
Hi. Thanx for the educational video's. Really nice to watch. I just did the similar measurement with my (from work :-D) scope Tek.MDO3014, with build-in function generator. I have put the 1Vpp and used 1k resistor. If I measure the time @630mVpp I get 20-25% more calculated capacitance. My DMM Fluke 185 agrees good with printed value on the capacitor. Measured time is in few us (microseconds) and rise time of the scoop is few ns (nanoseconds). So I don't know what I am doing wrong. Also used very short wires/leads to connect all together. 630mVpp would be 63% of 1Vpp. And of course, I know too that RC-time is @63% from the start. But... something is off... 🤔
With a measured risetime of a few uS, the capacitance will be a few nF. How are you connecting to the scope? BNC-cable with clips, or are you using a 10x probe? If you are using the former, that will add more than 100pF to your capacitor under test.
@w2aew hi. I have used a coax from the back of the scoop to bring the test signal, and have used the original probe, with the side 5cm gnd connection. Indeed the 3 tested C's are about a few nF.
Great inspiring video. Thank you ao much for the unvaluable contents and the clear and calm way to explain. A question: may this measurements be done also with the CAL output pin used and available at any scopes instead of the TDR circuit? would be good for measurements on the fly. Thanks again and keep going posting. Greets from Italy
Thanks for great contributions. How does the probe capacitor effect or side effect the results? On so datasheets (e.g. sensor ICs) in the test setup section, I saw they mentioned that the probe impedance too.
Ringing in a LC tank also gives an indication of how lossy the inductor is as well, lots of cycles = low loss, only a few = more resistor than inductor.
Hi, i have an inductor of 7 turns wound on a T44-6 (Yellow-Clear) Amidon Toroid. According formulas the inductance should be around 0.2 uH. I have an LCR meter that shows 0.37 uH so i am suspecting some measure error in the instrument. I attemped to compute the inductance following the method here proposed. So i made a tank with a capacitor of nominal 470 nF (actually is 489nF) and i used my signal generator with a square wave of 20 Khz. I measured the ring period about 30nsec. Resonant frequency is around 33.3 Mhz. Applying the formula f=1/(2*pi*sqrt(LC)) results in an inductance value (52 pH) by far lower than it should be. I tested square waves of different frequencies and i measured exactly the same resonant frequency of the tank around 33.3 Mhz. This seems to me perfectly normal since it does not matter the square wave period but only the rising edge. However, the inductor computed value is clearly wrong since the error is too huge. I guess something is wrong in my setup but i did not figured out yet what it could be. Is this method valid for inductance values in the below 1 uH ??
The LCR meter is probably the better way to go for small value inductors like this. But, you have to be very careful to account for (and minimize) the inductance of the leads and connections. Many LCR meters have a means to adjust or zero-out the lead inductance. To do this, you'd place a very small short between the connections where you would normally connect your inductor - note this reading, and subtract it from the reading you get with the inductor in its place. If the meter has a zero function, hit hte Zero button with the short in place, then this value will be automatically subtracted from the result with the inductor. For these low value inductors, the parasitic inductance and capacitance of the hookup for the tank measurement will often dominate the result unless special fixturing and probing is employed to minimize these effects.
A more accurate way to measure L is hook a decent signal generator across the LC circuit, and carefully tweak for a peak. With a little expertise, you can find the peak very accurately, and you can measure the frequency accurately with a counter. Also, you can use a series LC circuit and go for a null. That might be even more accurate. One more thing. Use a good signal generator, the kind that produces a pure sine wave. Unless you know pretty much what the L ought to be, you might end up peaking on a harmonic, if you use one of those horrible "service grade" generators.
Clyde Wary Yes, this too would work, but requires a signal generator with a variable frequency within the range of the LC tank resonance. The idea of this video is using a home-brewed fixed-frequency pulse generator along with your scope.
A speaker voice coil impedance is typically dominated by its resistance, so a simple ohmmeter will do. A more rigorous process is described here: www.epanorama.net/documents/audio/speaker_impedance.html
Thanks Alan. Think I found a well documented starting point here by looking at: document/how-guide/oscilloscope-measurement-lab-measuring-impedance-and-capacitance on tek-com
What are those terminal strips that you have soldered to plug in components called? I'm trying to find some online but don't know what to search for. Thanks Edit: Never mind, found out they are called machine pin sockets.
Great presentation as always! I've always been wondering, in an LC tank circuit, if the L and C were not physical components but parasitic L and C which is causing unwanted ringing on the output, what can be done to eliminate the ringing in order to get our clean square wave back?
You cannot entirely get rid of it but if you can get some resistance in there it will reduce the "Q" and quickly damp the ringing. You can sometimes also use clamping diodes.
sorryly i have a verry old scope. i have to do more math. but this is really good explained and remember me to some things during education. thank you:) Sorry for my poor english!
Hi Alan. I am impressed with your work and the quality of your videos. I am looking for a way to measure complex impedance of a circuit at resonance or in any other frequency using the oscilloscope, is this doable? Thanks , Werner.
I just checked my Owon DS7102V. 350ns rise time on the 1kHz calibration square wave with probe on x10. :-o. I ordered some HC parts (the AC ones are hard to get on eBay in DIP) and I'll be making one of the oscillators. I'm hoping to get something like a 15ns edge transition from HC. The first use will be to tweak some air core 700nH coils for a 20m low pass filter. Thanks! EA5IGC
Conceptually it is trivial; just put a blocking capacitor from the square wave signal source to the device under test. Then, have a mechanism to not instantly apply the DC (rc time constant; a resistor and filter capacitor feeding the device under test). If you simply switch high voltage on the device under test some of that is going to go through the blocking capacitor into your pulse generator.
Nice video! Thanks for the tutorial. I guess you could use a function generator to accomplish this? I don't recall seeing what frequency that you used for the square wave pulses. Are the input pulses at 5 volts?
It would seem that if you take an RC circuit and feed it a step, say 0 -> 10 V, DC input, then with a stopwatch, you could simply measure the time it takes for the cap to reach 6.32 Volts. Adjusting the value of R to give a long time should lead to accurate measurements of the cap. Have you tried this simple method? The input voltage and the resistor can be measured to fine accuracy so the result should be easy and I have done some of this with strangely mixed results.
That is really all that this video is doing - except using the scope to measure the delta-t to 63% (5 divisions out of 8) - and no need to use a very large resistor to get a human-measurable delta-t.
@@w2aew Sorry for the delay; open heart surgery and long-term covid played a role. Clearly, my method represented a proof of concept only. Next step is to be creating a simple circuit to interface with my HP 5316A Counter to replace the hand measurements of the time. (Interesting that in contrast to other physical sciences, the accurate measurement of time in electronics is strangely absent.) In any event the use of an electronic interface with an accurate counter to replace the hand measurement of time should improve the accuracy of the system by 4-5 orders of magnitude. Eye-balling the trace on a oscilloscope screen would have no chance to compete. At that point we could realistically begin to seriously address the true causes of inaccuracy of measurement of capacitor values, such as ESR of the meters and cablage and bread boards, etc. So, hows about designing that stop watch app for the counter. You can have all the credit. I just want to see it work. At 73 years old and poor health, I still enjoy my little lab, but I know my limitations. Best wishes to you and presented in the honest quest for improvement of the art, I remain your ... etc. Sanjursan. (One more thing. Have you seen Jack Lewis' book Modeling Engineering Systems? I, and many others I am sure, would love to hear your opinion of this amazing book, for use in the autodidact environment aiming at learning electronics. It is free on PDF.)
but that can also mean the cap has a high ESR, and i believe it can also be affected by the cap losing capacitance depending on how good the cap behaves at X frequency.
It might work for higher uH values, but don't think it would work well for nH level measurements. The parasitic inductance and capacitance of the fixture will be the limiting factor.
Even after 10 years, You're enlightening budding engineers like us. Kudos to you man!
The 8 divisions tip is epic
What a rarity! A TH-cam video by someone who really knows his electronics theory, clearly explaining what he's showing, and with good audio at a reasonable level. Excellent! :)
Zilog Z80?
@@Walter-Montalvo A little bit of Z80 a long time ago, and much more Z8. Now I've crossed over to the dark side with Microchip PICs. ;)
I'm enjoying your videos, thanks. Another easy measure on the scope is,
0.707 x 7 units = 5 units, useful for 3db points. Actual 4.949, closer than I can see!
Edit: Reading my mail 2 years late, to describe how I do this a little better, I set the Volt/Div so the signal is more than 7 units and then adjust the variable knob for 7 units, then I make any external circuit adjustments until the signal drops to 5 units, this is the 3db point.
Oooh - that is very handy - thanks!
One never gets around to doing back to basics but you have inspired me to do so. Your videos are so enthusing and fun. Keep up the good work. You are an excellent teacher.
Some of the most clear, to the point and instructional videos I've seen! Wow, keep up the good work! A joy to watch and an effective way to learn some basics.
I have to say, I think I've seen most you videos maybe even twice. I really appreciate the effort you've placed with all this content. I accidentally found your channel looking for ESR measurements with oscilloscopes and saw that you have a plethora of info on radio stuff as well. Well I could go on and on... In short, I have to say thank you very much for giving us all these invaluable lessons!
Heh, me too! More than twice for a couple of them. This channel is a superb resource :)
I've had the money set aside to buy my first real scope and I've been researching and humming and hawing over this for some time. Watching this finally pushed me over the edge and I made my decision. Just bought a Hantek DSO5202P from Amazon. It has almost everything I wanted, except integration and differentiation. But as it is, this one as $470, which is about $150 more than I planned to spend. I decided it was worth the extra money for a 2 channel scope vs 1 channel. I get the feeling the extra channel will be worth it. My only regret is doing this at 5am when I haven't slept yet. I'm far too excited to sleep now. Listen to me gushing like a school girl with a crush. =D
Now for my next dilema, buying a function generator.
Best of luck and learning with your new scope!
Great bench technique to pass along to our younger players, & led me back to your "Fast Edge Pulser / TDR" one; which videos earned my subscription. Nostalgia for the many fast pulse edges & TDR work in my misspent youth!
Reminds me of the electronics training I received in the US Army (circa 1991), straight and to the point highly effective knowledge transfer! Thank You!
Thank you. There's loads of "what is an oscilloscope?" videos and loads of TY2603L-Mega reviews, but not so many "things to do with one" vids. Really liking your other vids too.
I agree. Practical application scope videos are harder to come by.
You want to measure frequently at the zero crossings. It is hard to tell the peak, but the zero crossings are well defined. Also, it is more accurate to make the zero crossings as far apart on the CRT as possible either by adjusting the horizon sweep time or measure the time between a number of crossings and divide accordingly. It goes without saying that these zero crossings should all be the high to low or low too high crossings. Distortions in the wave can make your frequently measurement inaccurate if you measure half cycle times. Excellent video and I love your test fixtures.
Great explanation. Uses a mathod I've never tried before. 👍
One thing that I've noticed is that just about everyone makes the assumption that their viewers already know what units of measurement the formulas will be using when they do the math. But that average neophyte electronics student doesn't know that all the calculations answers will be in units of farads and henrys, or even in ohms. They most likely assume that the units will be in microfarads microhenrys and kilohms. So these units really need to be explicitly stated. Thanks for this useful video.
Thanks for a great treatment of my scope junction blog! Nice setup; when I do this I just slap-solder the parts together in the air. One point needs comment - for very small capacitors one needs to measure the capacitance of the fixture and the 10:1 scope probe first with the same technique so the probe and fixture capacitance can then be subtracted from the final measured value when the cap under test is added to the RC circuit.
The LC circuit is also known as a "tanktwanger" since the effect is so similar to twanging a guitar string.
Glad you liked it, and good common sense advice of course.
Thank you. Got a new scope and your channel is just gold. :D
You used the rise time measurement for "C", and used the frequency measurement for knowing "L". We can as well use the frequency measurement for determining the "C" as well, when we have a known value of "L". Very resourceful video indeed.
I've seen this explanation a few times so far yours was the simplest good work Sir.
Thank you for a very informative video and presentation of techniques. I liked it and the best thing was the quality of video and crystal clear voice; rather commentary. You are a good teacher. Thank you.
Using 74HC14 (as opposed to 74AC14), I'm getting 5ns rise time with 100nF + 3k3 RC. The squarewave runs at about 5kHz. The rise time seems to be pretty much independent of supply voltage between 2.5V through to 6V. I'm going to try packaging into an Altoids tin with 2xAA Alkaline => 3V supply. Mine's a Texas Instruments manufactured chip. I measured the rise time on my Owon DS7102V 100MHz Chinese scope. Compare this to the 350ns coming out of the scope's own 1kHz square wave probe calibration pins. 74HC14's are super-cheap and readily available in DIP on eBay. Thanks for a great circuit tip! EA5IGC
This is the best video on the subject so far. Well done!
I really appreciate your very hands-on review of basics! Quite useful. But, I imagine there is some limit to the range of capacitance if your input waveform is set at 5-6KHz.
The capacitance measurement is made by looking at the risetime of the signal (the RC time constant), so the frequency of the signal really doesn't enter into it, as long as it is low enough to permit the RC circuit to fully settle before the next half cycle.
Your videos are very educational & inspiring. Thank you so much for sharing. Please keep making more videos like this!
Great video. One of the best that I have seen. Now I can measure the C 's that I have to see if the value is as marked, the same for the L's I have. Since I am a retired EE I like to know the value as to how close the value as marked. I suggest that the value for measuring C's I would make the resistor 1% or better. The same applies for the C's to measuring the value L.
You could always measure the resistor so you know the actual value
thank you for this guide, I used the 1khz test signal from the oscilloscope but worked perfectly.
Great lab. What you just demo are is one of the first lab students perform in ac circuits courses. Brings back memories. You shot title your videos engineering lab ;)
Thank you for explaining this in so little time. It really takes a lot of skill!!! I'm watching your video for the first time, and I will definitely try to build the pulse generator. :)
MORE! MORE!! MORE SIMPLE TESTING AND MEASUREMENT TOOLS FOR DIY: great timeless content like that is worth like GOLD! THANKS A LOT, OM! 73!
Thanks for clear instruction and demonstration of this measurement. I was lucky to find a 2467 in January. I need to study the manual better. Very nice functionality.
When a work bench starts to get crowded, a decent calculator [or phone app] makes more sense than a laptop or PC.The 15C is a good model, too
well i found out my function generator uses the max038 chip witch the data sheets said square wave rise and fall for both are 12ns so i guess your circuit would work so i will build it thank you for your help in answering my questions even i majored in electronics in high school i forgot some and guess some things didnt stick because i must not of fully understood either but with your teaching i see it in a whole different light thank you again
You made the best instructional videos!
Very nicely done. Thanks... I loved your signal source, and the parallel outputs to make the edge faster...
I love that vintage Hewlett Packard calculator 😃. Take care of those and they will last a lifetime, as you are obviously doing.
Figuring out unknown variables is alot of fun this way. Thanks!
Yea - it's kind of like firing up the lawn tractor to mow a tiny patch of grass - a bit overkill on the equipment side, but a lot more fun!!
Thank you for sharing this. Very thorough explanation with formulas. Great presentation. I liked your video.
Thank you for showing this. I've been trying to measure inductance with my scope for some time now, but I could never figure out how to do it correctly.
Excellent, extremely helpful, very well presented and spoken.
Great videos, Self teaching EE here.Thanks!
you seem to be very knowledgeable both about fully utilizing your very capable scope and combining that with known formulas. Might I ask if you have a video that would show a person who has both a speaker, an audio amplifier, a frequency generator and a (lesser capable) scope than yours - how they would measure the 'free air impedance' of a speaker transducer at a desired frequency?
Great video!!!
Do you know how to measure the inductance "online"? This is when it is loaded, i.e. current flows through it and in the same time the inductance changes (ex. the core varies)? It's difficult but can be extremely useful.
Nice video, nice clear English with easy talking.
Alan, Thank you very much for the quick answer. I will really appreciate if you can share some quick tips meanwhile video is on the way. Congratulations for your Amazing job and to share all this tips.
With your ground free battery operated steep egde pulse generator you can use also the same circuit for the inductor as for the capacitor. It is not necessary to build up a resonator. Also the error is increasing because its much easier to get a tightly tolerated resistor than such capacitor. In the inductor case you just need to clamp your oscilloscope aross the terminals of the resistor to observe the voltage rising, which represents the current rising across the inductor. The math behind is the same.
Your videos are great, i'm learning so much. Thanks for the all the material and instruction.
At first glance, it seems to work with calibration output of the scope, although there might be some limitations. For example, on my scope, the rising edge of that signal is about 3.5us, therefore if we estimate that the rising time is the required time to go from the 10% up to the 90% of the signal amplitude, that would be about 2.197 times tau. Under those circumstances, if we want to see the complete signal, from 0 to 5 tau, with a 1k resistor, I would be able to estimate the capacitors values from about 1.33nF and up. Overall, there is always a way, but we need to experiment and do some homework to understand what is happening.
In memory of my good friend and colleague Roger. He would have taken a sheet of logarithmic graph paper and with it save a lot of calculations.
watching your videos is a kind of great pleasure...thank you so much
Your handwriting looks like Forest Mims III. Neatly written!
Thanks! I studied his Notebook series in the 1970s.
Can't thank you enough for sharing your knowledge and these educational videos!
Thank you for the information. I need to know how to measure unknown 3 phase line reactor. My concern is current rating and inductance. Thank you
Very interesting. One guy I worked with liked to test diodes with a low voltage 60 Hz signal. He would look at the response with his VOM, I think. I prefer to just measure the resistance both ways with an analog VOM, on the 1k or 10k scale.
One caution - the capacitor used for inductance measurement must be a high quality dielectric with minimum losses. ie, don't use a capacitor purchased from a Chinese supply chain source.
A couple days ago one of my colleagues tried this to test a transformer winding and could not get it to ring. After looking over his setup, I suggested he use a capacitor from my junkbox, not that brown ceramic disc of dubious origin. It turned out that was exactly the problem.
Your videos are very informative. Just got me a free scope (70s Siemens Oscillar) and your videos are a great help getting started with it. subscribed ;)
Hi. Thanx for the educational video's. Really nice to watch. I just did the similar measurement with my (from work :-D) scope Tek.MDO3014, with build-in function generator. I have put the 1Vpp and used 1k resistor. If I measure the time @630mVpp I get 20-25% more calculated capacitance. My DMM Fluke 185 agrees good with printed value on the capacitor. Measured time is in few us (microseconds) and rise time of the scoop is few ns (nanoseconds). So I don't know what I am doing wrong. Also used very short wires/leads to connect all together. 630mVpp would be 63% of 1Vpp. And of course, I know too that RC-time is @63% from the start. But... something is off... 🤔
With a measured risetime of a few uS, the capacitance will be a few nF. How are you connecting to the scope? BNC-cable with clips, or are you using a 10x probe? If you are using the former, that will add more than 100pF to your capacitor under test.
@w2aew hi. I have used a coax from the back of the scoop to bring the test signal, and have used the original probe, with the side 5cm gnd connection. Indeed the 3 tested C's are about a few nF.
Really informative video thanks. I need to measure some inductors for a induction heater
Great inspiring video. Thank you ao much for the unvaluable contents and the clear and calm way to explain. A question: may this measurements be done also with the CAL output pin used and available at any scopes instead of the TDR circuit? would be good for measurements on the fly. Thanks again and keep going posting. Greets from Italy
As long as the rising edge of the CAL output pin is substantially faster than the expected RC time constant, then yes.
Nice to see RPN on the old style HP calculator.
the best results that i've ever had was with the Gregs Electro Blog (i found it on google) without a doubt the most useful info that I've tried.
Pretty good presentation. In text below here, links to general information can be provided such that others can refer to details too.
Green band? I had a helmet fire for a minute until you showed the correction. Nice explanation. Thanks
That OG 350mHz scope is badass
My function generator is on its way, so I had to use the square wave generator on my 475 scope. It worked!
Thanks for great contributions. How does the probe capacitor effect or side effect the results? On so datasheets (e.g. sensor ICs) in the test setup section, I saw they mentioned that the probe impedance too.
Ringing in a LC tank also gives an indication of how lossy the inductor is as well, lots of cycles = low loss, only a few = more resistor than inductor.
So glad you have taken the time to make these very helpful videos for free. It was very well done PH D style great job many thanks 73's wb7qxu
Hi, i have an inductor of 7 turns wound on a T44-6 (Yellow-Clear) Amidon Toroid. According formulas the inductance should be around 0.2 uH. I have an LCR meter that shows 0.37 uH so i am suspecting some measure error in the instrument.
I attemped to compute the inductance following the method here proposed. So i made a tank with a capacitor of nominal 470 nF (actually is 489nF) and i used my signal generator with a square wave of 20 Khz. I measured the ring period about 30nsec. Resonant frequency is around 33.3 Mhz. Applying the formula f=1/(2*pi*sqrt(LC)) results in an inductance value (52 pH) by far lower than it should be. I tested square waves of different frequencies and i measured exactly the same resonant frequency of the tank around 33.3 Mhz. This seems to me perfectly normal since it does not matter the square wave period but only the rising edge. However, the inductor computed value is clearly wrong since the error is too huge. I guess something is wrong in my setup but i did not figured out yet what it could be. Is this method valid for inductance values in the below 1 uH ??
The LCR meter is probably the better way to go for small value inductors like this. But, you have to be very careful to account for (and minimize) the inductance of the leads and connections. Many LCR meters have a means to adjust or zero-out the lead inductance. To do this, you'd place a very small short between the connections where you would normally connect your inductor - note this reading, and subtract it from the reading you get with the inductor in its place. If the meter has a zero function, hit hte Zero button with the short in place, then this value will be automatically subtracted from the result with the inductor. For these low value inductors, the parasitic inductance and capacitance of the hookup for the tank measurement will often dominate the result unless special fixturing and probing is employed to minimize these effects.
A more accurate way to measure L is hook a decent signal generator across the LC circuit, and carefully tweak for a peak. With a little expertise, you can find the peak very accurately, and you can measure the frequency accurately with a counter. Also, you can use a series LC circuit and go for a null. That might be even more accurate. One more thing. Use a good signal generator, the kind that produces a pure sine wave. Unless you know pretty much what the L ought to be, you might end up peaking on a harmonic, if you use one of those horrible "service grade" generators.
Clyde Wary Yes, this too would work, but requires a signal generator with a variable frequency within the range of the LC tank resonance. The idea of this video is using a home-brewed fixed-frequency pulse generator along with your scope.
Now THIS is really interesting and well presented! You have a new subscriber! Thank you for uploading.
You make this stuff look easy!
Great vid, I just found your channel. Will keep viewing.
Great video. How can this be used to determine impedance of a coil/ speaker?
A speaker voice coil impedance is typically dominated by its resistance, so a simple ohmmeter will do. A more rigorous process is described here:
www.epanorama.net/documents/audio/speaker_impedance.html
Simple and effective method . Thank you for sharing .
Nice tutorial! I now really miss my old analog scope. It's 70 pounds and 3 feet long!
Thanks Alan. Think I found a well documented starting point here by looking at: document/how-guide/oscilloscope-measurement-lab-measuring-impedance-and-capacitance on tek-com
Instead of the fast pulse generator, can I use a piezo ignitor? Thanks for the very informative videos 👍
What are those terminal strips that you have soldered to plug in components called? I'm trying to find some online but don't know what to search for.
Thanks
Edit: Never mind, found out they are called machine pin sockets.
Great presentation as always! I've always been wondering, in an LC tank circuit, if the L and C were not physical components but parasitic L and C which is causing unwanted ringing on the output, what can be done to eliminate the ringing in order to get our clean square wave back?
You cannot entirely get rid of it but if you can get some resistance in there it will reduce the "Q" and quickly damp the ringing. You can sometimes also use clamping diodes.
Bro that worked pretty good. Thanks for advice you just saved my hours. 😘
This is awesome... Is it ok to use calibration output points on the scope ( most scope have 5V p-p and 1KHZ waveform) for as a fast edge source?
sorryly i have a verry old scope. i have to do more math. but this is really good explained and remember me to some things during education.
thank you:)
Sorry for my poor english!
Such a beautiful oscillation. Thank you.
Hi Alan. I am impressed with your work and the quality of your videos. I am looking for a way to measure complex impedance of a circuit at resonance or in any other frequency using the oscilloscope, is this doable? Thanks , Werner.
Excellent contents/presentation, many thanks
Thank you, very nice video. When I grow up I wanna be like you.
Great little video.
I just checked my Owon DS7102V. 350ns rise time on the 1kHz calibration square wave with probe on x10. :-o. I ordered some HC parts (the AC ones are hard to get on eBay in DIP) and I'll be making one of the oscillators. I'm hoping to get something like a 15ns edge transition from HC. The first use will be to tweak some air core 700nH coils for a 20m low pass filter.
Thanks!
EA5IGC
Super cool still in 2020 ;)
Real Electronics (tm) ! Love that oscilloscope and good old reliable HP calculator (I have that same calculator and many others).
great video. thanks. Could you tell us how to measure the Q factor, R(ohms),dissipationfactor of a coil on scope please ?
Hi, Alan. Another great video! Thanks for your efforts! Is there any way to add a DC offset to this circuit, to test caps at their working voltage?
Conceptually it is trivial; just put a blocking capacitor from the square wave signal source to the device under test. Then, have a mechanism to not instantly apply the DC (rc time constant; a resistor and filter capacitor feeding the device under test). If you simply switch high voltage on the device under test some of that is going to go through the blocking capacitor into your pulse generator.
Very nice presentation - thank you
Good, simple video. Thanks for sharing with us.
Nice video! Thanks for the tutorial. I guess you could use a function generator to accomplish this? I don't recall seeing what frequency that you used for the square wave pulses. Are the input pulses at 5 volts?
1-10kHz works fine. Yes, a function generator can be used. It was 5Vpp in this case.
It would seem that if you take an RC circuit and feed it a step, say 0 -> 10 V, DC input, then with a stopwatch, you could simply measure the time it takes for the cap to reach 6.32 Volts. Adjusting the value of R to give a long time should lead to accurate measurements of the cap. Have you tried this simple method? The input voltage and the resistor can be measured to fine accuracy so the result should be easy and I have done some of this with strangely mixed results.
That is really all that this video is doing - except using the scope to measure the delta-t to 63% (5 divisions out of 8) - and no need to use a very large resistor to get a human-measurable delta-t.
@@w2aew Sorry for the delay; open heart surgery and long-term covid played a role. Clearly, my method represented a proof of concept only. Next step is to be creating a simple circuit to interface with my HP 5316A Counter to replace the hand measurements of the time. (Interesting that in contrast to other physical sciences, the accurate measurement of time in electronics is strangely absent.) In any event the use of an electronic interface with an accurate counter to replace the hand measurement of time should improve the accuracy of the system by 4-5 orders of magnitude. Eye-balling the trace on a oscilloscope screen would have no chance to compete. At that point we could realistically begin to seriously address the true causes of inaccuracy of measurement of capacitor values, such as ESR of the meters and cablage and bread boards, etc. So, hows about designing that stop watch app for the counter. You can have all the credit. I just want to see it work. At 73 years old and poor health, I still enjoy my little lab, but I know my limitations. Best wishes to you and presented in the honest quest for improvement of the art, I remain your ... etc. Sanjursan. (One more thing. Have you seen Jack Lewis' book Modeling Engineering Systems? I, and many others I am sure, would love to hear your opinion of this amazing book, for use in the autodidact environment aiming at learning electronics. It is free on PDF.)
but that can also mean the cap has a high ESR, and i believe it can also be affected by the cap losing capacitance depending on how good the cap behaves at X frequency.
Great video. Do you think this set up will work in the micro or nano Henry range? It seems I'm always guessing with small value coils...
It might work for higher uH values, but don't think it would work well for nH level measurements. The parasitic inductance and capacitance of the fixture will be the limiting factor.
Nice one Alan, thanks for this educational video excellently explained again!
Thank you for video (I must watch again)
Very interesting video, lots of useful information. Thanks.
Thankkk youuu alllann!!!! I needed this right now