#90: Measure Capacitors and Inductors with an Oscilloscope and some basic parts

[@aqib2000]

The 8 divisions tip is epic

[@mavamQ]

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.

[@w2aew]

Oooh - that is very handy - thanks!

[@syedshigarfmashaam9974]

Even after 10 years, You're enlightening budding engineers like us. Kudos to you man!

[@petti78]

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.

[@ZilogBob]

What a rarity! A KZbin video by someone who really knows his electronics theory, clearly explaining what he's showing, and with good audio at a reasonable level. Excellent! :)

[@Walter-Montalvo]

Zilog Z80?

[@ZilogBob]

@@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. ;)

[@DucatiMTS1200]

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.

[@JlerchTampa]

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!

[@jeromekerngarcia]

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!

[@DuanvantSlot]

Thank you. Got a new scope and your channel is just gold. :D

[@VoidHalo]

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.

[@w2aew]

Best of luck and learning with your new scope!

[@Dullthud007]

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.

[@Greg-lo1tl]

I agree. Practical application scope videos are harder to come by.

[@nsknyc]

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!

[@daver1964]

Heh, me too! More than twice for a couple of them. This channel is a superb resource :)

[@bullshyte8585]

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.

[@w2aew]

Glad you liked it, and good common sense advice of course.

[@acmefixer1]

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.

[@ronjones4069]

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.

[@marcusjenkins]

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

[@jspencerg]

You made the best instructional videos!

[@valiza123]

thank you for this guide, I used the 1khz test signal from the oscilloscope but worked perfectly.

[@syedhaider7121]

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.

[@mkschreder]

This is the best video on the subject so far. Well done!

[@wadehicks9270]

I've seen this explanation a few times so far yours was the simplest good work Sir.

[@u0000]

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 ??

[@w2aew]

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.

[@roundhouse283]

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 ;)

[@Taran72]

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. :)

[@Steve_LSP]

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

[@w2aew]

As long as the rising edge of the CAL output pin is substantially faster than the expected RC time constant, then yes.

[@alocin110]

Thank you for sharing this. Very thorough explanation with formulas. Great presentation. I liked your video.

[@jasoneyes01]

Figuring out unknown variables is alot of fun this way. Thanks!

[@w2aew]

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!!

[@Debraj1978]

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.

[@rtecha.m9648]

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

[@dougkiss7630]

Excellent, extremely helpful, very well presented and spoken.

[@jimifarrell3667]

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

[@ronaldschild157]

I love that vintage Hewlett Packard calculator 😃. Take care of those and they will last a lifetime, as you are obviously doing.

[@henrihoopkins2822]

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.

[@larrybud]

You could always measure the resistor so you know the actual value

[@x86cowboy]

Your videos are very educational & inspiring. Thank you so much for sharing. Please keep making more videos like this!

[@vanningale495]

Very nicely done. Thanks... I loved your signal source, and the parallel outputs to make the edge faster...

[@jspencerg]

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.

[@darqen271]

Great videos, Self teaching EE here.Thanks!

[@AxelWerner]

MORE! MORE!! MORE SIMPLE TESTING AND MEASUREMENT TOOLS FOR DIY: great timeless content like that is worth like GOLD! THANKS A LOT, OM! 73!

[@hansblooeyribbon4207]

Hello W2aew. The inductors I'm testing or measuring are .1H to 10H for audio equalizers. Would the procedure/ math here remain the same?

[@JohnSmith-gp1kr]

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.

[@ernestb.2377]

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... 🤔

[@w2aew]

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.

[@ernestb.2377]

@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.

[@hoptoad]

Your videos are great, i'm learning so much. Thanks for the all the material and instruction.

[@andrewferg8737]

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...

[@w2aew]

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.

[@yoramstein]

Nice video, nice clear English with easy talking.

[@waynegram8907]

When measuring DC Decoupling capacitors on the input of audio amplifier circuits they use different values 0.001uf, 0.01uf, 0.1uf, 1uf, 2uf, 5uf. What formula do you use to know what frequency range the capacitor value will pass a band of frequencies? Because 1uf - 0.01uf = a difference of 0.9uf and 0.01uf - 0.001uf is a difference of 0.09uf. The difference going down in capacitance values is 0.9uf of a difference. Sweeping the frequency range from 20hz to 20Khz the difference in capacitance values will make the band of frequencies roll off, I'm guessing at a difference of 0.9% as you select different capacitor values from 0.001uf, 0.01uf, 0.1uf, 1uf, 2uf, 5uf? The band of frequency that is passing will roll off at a difference of 10%?

[@williamogilvie6909]

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.

[@gkdresden]

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.

[@hans-jrgenbernhardtsen8506]

Instead of the fast pulse generator, can I use a piezo ignitor? Thanks for the very informative videos 👍

[@rolfw2336]

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.

[@w2aew]

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.

[@Soupie62]

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

[@nnamrehck]

You make this stuff look easy!

[@AltayBrusan]

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.

[@ilierazvan5485]

Is this method useful for measuring small inductors like 50nH to 100nH ?

[@w2aew]

Unfortunately, not really.

[@micahwright7760]

I am doing a project which compares different inductors on the same circuit for their efficiency. One of the criteria is that I have to implement some sort of calculus element for the project to be gradable. Could I measure and compare the area of the curve for one cycle of the frequency? Would this measurement show that the inductor with the most area is the most efficient? I would take the area under the curve for the very first cycle.

[@sheaton319]

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.

[@SimpleEnough2k9]

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.

[@waynegram8907]

Measuring the inductors Ringing is the resonance frequency? But when calculating the RLC resonance frequency it doesn't equal the same result when measuring the inductors ringing frequency, any reasons why they are different?

[@tunicana]

watching your videos is a kind of great pleasure...thank you so much

[@TonyButchT]

Can't thank you enough for sharing your knowledge and these educational videos!

[@friddevonfrankenstein]

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 ;)

[@Debraj1978]

Would it still work (by series resonance), if we just keep the series capacitor and inductor (remove the parallel cap with inductor)? And probe the connecting between the C and L point?

[@w2aew]

Not really - remember a parallel resonant circuit looks very high impedance at resonance, a series resonant circuit appears very low impedance at resonance.

[@utoopuser]

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.

[@jaredwirth3990]

Your handwriting looks like Forest Mims III. Neatly written!

[@w2aew]

Thanks! I studied his Notebook series in the 1970s.

[@wernerlopez5433]

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.

[@sstrama]

Pretty good presentation. In text below here, links to general information can be provided such that others can refer to details too.

[@diedraak1]

Great video. How can this be used to determine impedance of a coil/ speaker?

[@w2aew]

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

[@CanadairCL44]

Now THIS is really interesting and well presented! You have a new subscriber! Thank you for uploading.

[@waynegram8907]

To Correct the 90 degree phase angle in capacitors and inductor to make it "0" degrees would need a power factor of "0" which should shift the phase from 90 degrees to 0 zero degrees?

[@hrjm7544]

is the 10pf part of the scope probe, as your video showing the board you built has only 1 cap on it. Is the one on the board the 1nf. Please reply

[@w2aew]

The 10pF cap is the small orange disk capacitor that is located between the two rows of pin sockets. I point to it at 4:28 in the video. The 1nF cap is connected to the pin sockets with the unknown inductor.

[@mikefinn2101]

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

[@visweswararaokalla411]

nice video this is the video i am looking for, i don't have inductance meter, even function generator, so i programmed AVR(atmega164p) to generate PWM 6KHz of 50% duty cycle and followed this and measured inductance sucessfully. the measured value is 8.9uH and mentioned on it is 10uH (maybe the component tolerance ) but is there any particular frequency to measure the accurate value of inductance? thank you sir.

[@w2aew]

Not really. Lower inductance values require higher frequency to measure.

[@hackercop]

Really informative video thanks. I need to measure some inductors for a induction heater

[@hrjm7544]

for your videos, where would I go to see a list, as the video come up as #. for this video or similar topics, I have a 20MH analog scope, is this good enough for general hobby work, or what size of a used MH scope do you recommend as a min value.

[@w2aew]

One of my subscribers compiled a complete list, but it is not published online at this time. A 20MHz scope is a nice starter scope that will be fine for a lot of hobby uses.

[@josemartin6865]

Hi Nice videos. Very well done. Question for you.. With your R&S 9khz to 1.1Ghz sig gen.. Are the rubber buttons hard to push? I mean you have to push them fairly hard for them to work? Mine are like that and I'm debating if I should take the front panel off and clean the carbon contacts inside.

[@w2aew]

No, the buttons aren't hard to push on sig gen.

[@josemartin6865]

***** Ok then I have some work to do lol

[@keithostertag]

Hi Alan- another question: I haven't tried this yet, but I was thinking one way to determine a good rate would be 5 x the RC time constant or so. Yet, I recently came upon this article which uses 10HZ ! which seems unusual to me. What do you think? KZbin won't allow to post the webaddress, but you can search on the title which is "Quick Methods for Reliable Component Testing" by Dennis Weller, Agilent Technologies, March 2011 on the evaluationengineering site.

[@Lyrics9801]

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.

[@IsaacOLEG]

Nice and fun ! What is the name of those trhu boards with rivets ? thanks . I am wondering something : may I use a cheap wave generator mimic alternative current with it ? I thought I could test a full wave bridge rectifier with a sinusoidal by entering it in a T shape BNC, it seemed to work on the oscilloscope, (showing rectified waves) but I am unsure it really did the job . Did you make avideo on that sort of subject ? Sorry for the out of topic , Thank you

[@w2aew]

The board is an old piece of Vectorboard (www.vectorelect.com/prototyping-boards.html).

[@IsaacOLEG]

@@w2aew Thank you (is the reasoning for my other question totally wrong ?) regards

[@IsaacOLEG]

@@w2aew ​ Thank you I am trying to understand why an alimentation is not starting, with CM6802 Can you tell me what I use to check the mosfets outputs . There is a comparator I suppose before the CM , The oscilloscope show no stable SB voltage but something at 4 then 8 V alterning at 1Hz +-, and I do not understand what can be is causing this . each capacitor I test seem to be good . I am far from being at the level of comprehension for that type of job but I wish to understand something of the primary then secondary portion of a classical alimentation (as one for a PC ATXtype) it is on a NAS alim board.. A finger pointing a direction would be largely enough for my pleasure ;) as "do measured tensions show the place where something is wrong? May I look for RT & CT and VREF ? A simple experimental circuit /video to understand how is working an oscillator would please me a lot Sorry to be long winding and thanks for reading me / regards

[@w2aew]

@@IsaacOLEG You can use a function generator to mimic AC signals for the experiment you describe - the only difference is that AC/line impedance is typically very low, while the output impedance of a function generator is typically 50 ohms (or higher), so you may experience loading issues with the function generator that you won't see with the AC/line powered experiment.

[@tubeDude48]

Your R-C circuit for your Fast-Edge Generator shows a 6.8k resistor, but I can't read the Cap. is it 4.7nF or 47nF. You mentioned another video that you did on this circuit, but I can't seem to locate it. Thanks.

[@SuperJetjockey]

Green band? I had a helmet fire for a minute until you showed the correction. Nice explanation. Thanks

[@martinsleguizamon]

Is there a way to measure the selectivity (Q) of that LC tank circuit with the oscilloscope ? Thank you.

[@w2aew]

One thing to remember that the Q will depend on the circuitry around it (loaded Q). So, you'd have to measure it "in-circuit" - usually by sweeping a signal through it.

[@BryanByTheSea]

Is it critical to use a AC or will a HC variant of the 74xx14 suffice. I am not sure if a super fast fast edge of the oscillator is critical for measuring inductance or capacitance. Thanks

[@sanjursan]

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.

[@w2aew]

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.

[@sanjursan]

@@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.)

[@itrstt66]

hi i was looking for a screen color filter for my 2467 and got on eye on this video thumbnail. do you have any idea of where can i get a filter like yours in organge? and what is the technical name for those filters?

[@w2aew]

The color is from the phosphor in the CRT, not from an external filter.

[@itrstt66]

@@w2aew Well i have on orange filter and the crt is blue, and i appears yellow because of the filter. by the way do you know where can a i get another orange filter?

[@XPFTP]

i dont see a math video for the caps.. iam testing a 473 cap. and i can not get it to add up..the old scope i use. i set the T/D on main dial.. the screen doesnt give any info. i count left to rite 4 of the 5 subgraticules. t/d set to 50u. 50/5=10 10/1000= 0.01.. thats with the 473 in place.. so iam lost.. lol if theres a video or something i can see.. would be cool.. the trace is at 8D. if i go more it slopes over more. or is that what we want. as much slope to the flat. thank you kb2wvo

[@conflubmw1505]

Nice to see RPN on the old style HP calculator.

[@Tekjive]

That OG 350mHz scope is badass

[@Atetus94]

Super cool still in 2020 ;)

[@JosiahRitchie]

My Siglent SDS1102CML has a 1Khz square wave on it. Could I put that into the circuit in the place of the fast edge pulser to accomplish something similar? Sorry if this is a super-newb question. I've been trying to figure out how to measure salvaged parts to make my own LC Meter.

[@w2aew]

+Josiah Ritchie You can give it a try. You may have to characterize the output impedance of the circuit creating the squarewave to be sure it doesn't impact (or to include it in) the calculation for the RC time constant for checking caps. On the inductor test - it's usability will depend on how fast the rise/fall edges are - you need fast edges to inject the high frequency energy to ring the LC tank circuit for the inductor test.

[@JosiahRitchie]

Thank you for your reply. I'll consider that as I play with it. Your direction on what to be aware of gives me some confidence knowing what to consider as possible variance. Thank you!

[@snaprollinpitts]

hey 2 whiskeys, for a lack of better name for you, that is a cool method/ way to use your scope. I have a question for the professor, I have given capacitor that I need to resonate with an inductor that I will have to wind. But I have found that if the coil is too big or too small it won't resonate. Do you know of good way to find this value that is within the parameters of resonance. that is within a given frequency range. thanks mk

[@w2aew]

snaprollinpitts It's a good idea to keep a couple of "known" capacitors around to give you good frequency coverage. Also, you might want to use caps that have a capacitive reactance value within reason at the expected operating frequency range. By within reason, I mean a Xc of something >10ohms but less than a few Kohms.

[@Yorumcu63]

Thank you for video (I must watch again)

[@rapsod1911]

Can you built ANDERSON's BRIDGE for inductance measurement? What methods are used to measure inductance in nH range?

[@waynegram8907]

how can you measure the EMF & C-EMF counter in inductors? what lab equipment measures EMF and Counter EMF in inductors and transformers?

[@t1d100]

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?

[@thomasmaughan4798]

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.

[@Darkblue332]

Simple and effective method . Thank you for sharing .

[@46bovine]

Great vid, I just found your channel. Will keep viewing.

[@warywolfen]

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.

[@bullshyte8585]

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.

[@anonhollmuller4032]

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!

[@tonythediyer8537]

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?

[@w2aew]

1-10kHz works fine. Yes, a function generator can be used. It was 5Vpp in this case.

[@sachingoyal45]

could we use a dual channel oscilloscope insted of fast edge pulse generator to create the square pulse ?And will this method work for high fequency inductor(50khz) with ferrite core ?

[@w2aew]

+Sachin Goyal I'm not sure how you would substitute a dual channel scope for a fast edge pulse generator. Can you explain what you had in mind?

[@tiwanacote]

Nice Video! How you could compute error in that measuring method? Which is the correct way to obtain an error bound? Regards!

[@w2aew]

+Maximiliano Bertotto There would be a lot of factors to consider. Smaller values will be subject to more error because of the parasitics in the setup. Errors are high enough that it's probably not worth the exercise. These methods will likely give you results within 10% or so, or a little better with great care.