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.
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.
What a rarity! A RUclips video by someone who really knows his electronics theory, clearly explaining what he's showing, and with good audio at a reasonable level. Excellent! :)
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.
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!
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.
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!
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.
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.
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.
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.
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.
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. :)
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
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?
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.
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 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
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 ;)
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 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
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.
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 informative. Just got me a free scope (70s Siemens Oscillar) and your videos are a great help getting started with it. subscribed ;)
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.
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.
I use this principle to measure inductance of inductors used in power circuits, speaker crossovers and relays too, with ferrite cores. I set the test current to the steady state value. Using inductor meters you do not measure an accurate value because you have no idea where on the B-H curve of the core material the inductor is operating. Inductor meters are accurate for air cored inductors.
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.
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.
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.
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.
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.
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.
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
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.
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? RUclips 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.
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.
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?
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?
+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.
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.
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.)
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
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.
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 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.
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.
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 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
@@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.
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.
w2aew, LCR meters have an SERIES/PARALLEL mode on the DE5000 LCR meter. This puts the resistance of the inductors either in series or in parallel. An inductor is a Series L+R+C or is it L/R/C in parallel?I'm not sure which mode to use when measure inductance of a inductor or coil
In general it is not terribly important which model you use, but the manual has some suggestions of which model to use based on whether you're measuring low or high values. See page 5 on the manual (www.ietlabs.com/pdf/Manuals/DE_5000_im.pdf). I'd say that for capacitance, high values would be anything about about 1uF. For inductance, high values would be anything above a few hundred uH.
Other techs say when measuring a coil or inductor using a DE5000 to use the SERIES mode when measuring Inductance and use the PARALLEL mode when measuring capacitance. The Series mode is putting the ESR resistance in series with the inductance and the parallel mode is putting the ESR resistance in parallel. My other LCR meter "doesn't" have a SERIES/PARALLEL mode. I'm not sure why LCR meter have a series/parallel mode for measuring inductors
@@waynegram8907 Read the manual, it describes why there is a series and parallel mode. Meters that don't have this function simply ignore the parasitic resistance.
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?
Yes I see you used the VAR vernier to make the voltage to fit 8 divisions to measure the time constant 63%. I thought when you adjusted the VAR vernier it changes/alters the amplitude voltage so that its not a real absolute true voltage but just a relative voltage, not sure if that is true or not?
Yes, it is relative, but that is what we want in this case. By making the peak voltage occupy 8 divisions, we know that 5 divisions is 63%. All relative.
I would think it would give you a "false 63% time constant" because you have altered the peak voltage by stretching it or collapsing it using the VAR vernier. In some Oscope manuals I think they give a formula to use when you have the VAR vernier adjusted Multiplied by the Volts per Division, I'm not sure what the formula is but you have to use a formula to "add in" the VAR vernier to the volts per division. You have mostly used the VAR vernier to measure Rise time/fall time and Time constant. What else can you use to measure using the VAR vernier? Because older electronic technicians in the 50's and 60's would use the VAR vernier often I heard because Oscopes in the 50's and 60's used the VAR vernier much more for some reasons you had to use the VAR vernier to make measurements because the Oscopes were different in the 50's and early 60's.
@@waynegram8907 No, it won't give a false 63% time constant. 5 divisions is always 63% of 8 divisions, regardless of how many volts it represents. So, there is no problem. On the older scopes from the 50's and 60's, the vertical scale was NOT calibrated, so you would put a KNOWN voltage into the scope and adjust the vernier for a certain number of divisions so that you would have a calibrated scale. That is not necessary on more modern scopes (anything less than 40 or 50 years old).
What was causing the vertical scale to NOT be calibrated in the older scopes? was their a stage/circuit missing inside the Oscope that new Oscopes have that calibrates the vertical scale?I would think using the VAR vernier is stretching or squeezing the voltage amplitude which would change and alter the voltage amplitude to another new "instantaneous value". But you're saying that when you're adjusting the VAR vernier that its NOT changing/altering the Instantaneous voltage value , its just only a visual thing that's its stretching and squeezing the amplitude only in a visual display but "not" changing the Instantaneous value of the voltage?
@@waynegram8907 Back in these early scope days, it was very difficult to make a vertical front end and deflection system for the early CRTs that would operate consistently and hold a particular calibration in a cost effective manner. The VAR control just changes the gain or scaling of the waveform, it does not just compress the extremes, so the signal maintains its linearity.
in the learning stages. the time/div. is there a chart that shows what decmials to enter for each time or to learn more of the M , U secs. iam guessing M is micro. but what is U and a example of the numbers pluged in for cap values. ive tested a few known caps. and numbers are not matching at all..
bug ya one more time olmand. i have the analog hp1740a. Sq's on screen as normal. the lil marks also .. cant rememebr how to spell that big 10 dollar word ... so if iam at .1mSec the sq's are .1 each then divid that by 5 for each sub mark on the Gline..
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%?
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?
Not really - remember a parallel resonant circuit looks very high impedance at resonance, a series resonant circuit appears very low impedance at resonance.
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.
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.
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
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.
No real benefit to this method other than: - an excuse to play with you oscilloscope - gain some better understanding of how capacitors and inductors behave. So, no, this method was show mainly as an educational exercise, not necessarily a more practical way to measure capacitors and inductors.
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.
Even after 10 years, You're enlightening budding engineers like us. Kudos to you man!
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!
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.
What a rarity! A RUclips 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. ;)
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.
The 8 divisions tip is epic
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!
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!
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 :)
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.
Thank you. Got a new scope and your channel is just gold. :D
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.
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.
This is the best video on the subject so far. Well done!
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.
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.
I've seen this explanation a few times so far yours was the simplest good work Sir.
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. :)
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
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?
Thank you for sharing this. Very thorough explanation with formulas. Great presentation. I liked your video.
Your videos are very educational & inspiring. Thank you so much for sharing. Please keep making more videos like this!
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.
You made the best instructional videos!
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 the information. I need to know how to measure unknown 3 phase line reactor. My concern is current rating and inductance. Thank you
Excellent, extremely helpful, very well presented and spoken.
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.
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 ;)
MORE! MORE!! MORE SIMPLE TESTING AND MEASUREMENT TOOLS FOR DIY: great timeless content like that is worth like GOLD! THANKS A LOT, OM! 73!
Very nicely done. Thanks... I loved your signal source, and the parallel outputs to make the edge faster...
Your videos are great, i'm learning so much. Thanks for the all the material and instruction.
Nice video, nice clear English with easy talking.
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!!
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.
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
thank you for this guide, I used the 1khz test signal from the oscilloscope but worked perfectly.
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.
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.
watching your videos is a kind of great pleasure...thank you so much
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 ;)
Now THIS is really interesting and well presented! You have a new subscriber! Thank you for uploading.
Can't thank you enough for sharing your knowledge and these educational videos!
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
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.
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.
Instead of the fast pulse generator, can I use a piezo ignitor? Thanks for the very informative videos 👍
I use this principle to measure inductance of inductors used in power circuits, speaker crossovers and relays too, with ferrite cores. I set the test current to the steady state value. Using inductor meters you do not measure an accurate value because you have no idea where on the B-H curve of the core material the inductor is operating. Inductor meters are accurate for air cored inductors.
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.
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.
Great video, could you please clear the fog in my brain on the RC setup. Where does the capacitor discharge to between pulses.
Thru the series resistor into the generator output and its termination.
Many thanks, instruments coupling might be a very interesting topic, 👍
I love that vintage Hewlett Packard calculator 😃. Take care of those and they will last a lifetime, as you are obviously doing.
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.
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.
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.
No, the buttons aren't hard to push on sig gen.
***** Ok then I have some work to do lol
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?
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.
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
Great videos, Self teaching EE here.Thanks!
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.
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? RUclips 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.
You make this stuff look easy!
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.
Not really. Lower inductance values require higher frequency to measure.
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.
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?
Nice Video! How you could compute error in that measuring method? Which is the correct way to obtain an error bound?
Regards!
+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.
Is this method useful for measuring small inductors like 50nH to 100nH ?
Unfortunately, not really.
Hello W2aew. The inductors I'm testing or measuring are .1H to 10H for audio equalizers. Would the procedure/ math here remain the same?
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
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.
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.)
Can you built ANDERSON's BRIDGE for inductance measurement? What methods are used to measure inductance in nH range?
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
Pretty good presentation. In text below here, links to general information can be provided such that others can refer to details too.
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.
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 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.
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.
It would have been nice if you compared your values to what a good LCR meter says to see how accurate this method is.
What peak to peak voltage are you getting with the fast edge generator ? great videos by the way.
It is dependent on the supply voltage applied to the circuit - the output swings close to rail-to-rail.
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
The board is an old piece of Vectorboard (www.vectorelect.com/prototyping-boards.html).
@@w2aew Thank you (is the reasoning for my other question totally wrong ?) regards
@@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
@@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.
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.
w2aew, LCR meters have an SERIES/PARALLEL mode on the DE5000 LCR meter. This puts the resistance of the inductors either in series or in parallel. An inductor is a Series L+R+C or is it L/R/C in parallel?I'm not sure which mode to use when measure inductance of a inductor or coil
In general it is not terribly important which model you use, but the manual has some suggestions of which model to use based on whether you're measuring low or high values. See page 5 on the manual (www.ietlabs.com/pdf/Manuals/DE_5000_im.pdf). I'd say that for capacitance, high values would be anything about about 1uF. For inductance, high values would be anything above a few hundred uH.
Other techs say when measuring a coil or inductor using a DE5000 to use the SERIES mode when measuring Inductance and use the PARALLEL mode when measuring capacitance. The Series mode is putting the ESR resistance in series with the inductance and the parallel mode is putting the ESR resistance in parallel. My other LCR meter "doesn't" have a SERIES/PARALLEL mode. I'm not sure why LCR meter have a series/parallel mode for measuring inductors
@@waynegram8907 Read the manual, it describes why there is a series and parallel mode. Meters that don't have this function simply ignore the parasitic resistance.
Oh ok thanks, I'm not normally use to using LCR meters that has this parasitic resistance function.
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?
Bro that worked pretty good. Thanks for advice you just saved my hours. 😘
Yes I see you used the VAR vernier to make the voltage to fit 8 divisions to measure the time constant 63%. I thought when you adjusted the VAR vernier it changes/alters the amplitude voltage so that its not a real absolute true voltage but just a relative voltage, not sure if that is true or not?
Yes, it is relative, but that is what we want in this case. By making the peak voltage occupy 8 divisions, we know that 5 divisions is 63%. All relative.
I would think it would give you a "false 63% time constant" because you have altered the peak voltage by stretching it or collapsing it using the VAR vernier. In some Oscope manuals I think they give a formula to use when you have the VAR vernier adjusted Multiplied by the Volts per Division, I'm not sure what the formula is but you have to use a formula to "add in" the VAR vernier to the volts per division. You have mostly used the VAR vernier to measure Rise time/fall time and Time constant. What else can you use to measure using the VAR vernier? Because older electronic technicians in the 50's and 60's would use the VAR vernier often I heard because Oscopes in the 50's and 60's used the VAR vernier much more for some reasons you had to use the VAR vernier to make measurements because the Oscopes were different in the 50's and early 60's.
@@waynegram8907 No, it won't give a false 63% time constant. 5 divisions is always 63% of 8 divisions, regardless of how many volts it represents. So, there is no problem.
On the older scopes from the 50's and 60's, the vertical scale was NOT calibrated, so you would put a KNOWN voltage into the scope and adjust the vernier for a certain number of divisions so that you would have a calibrated scale. That is not necessary on more modern scopes (anything less than 40 or 50 years old).
What was causing the vertical scale to NOT be calibrated in the older scopes? was their a stage/circuit missing inside the Oscope that new Oscopes have that calibrates the vertical scale?I would think using the VAR vernier is stretching or squeezing the voltage amplitude which would change and alter the voltage amplitude to another new "instantaneous value". But you're saying that when you're adjusting the VAR vernier that its NOT changing/altering the Instantaneous voltage value , its just only a visual thing that's its stretching and squeezing the amplitude only in a visual display but "not" changing the Instantaneous value of the voltage?
@@waynegram8907 Back in these early scope days, it was very difficult to make a vertical front end and deflection system for the early CRTs that would operate consistently and hold a particular calibration in a cost effective manner. The VAR control just changes the gain or scaling of the waveform, it does not just compress the extremes, so the signal maintains its linearity.
in the learning stages. the time/div. is there a chart that shows what decmials to enter for each time or to learn more of the M , U secs. iam guessing M is micro. but what is U and a example of the numbers pluged in for cap values. ive tested a few known caps. and numbers are not matching at all..
m = milliseconds, u = microseconds, and n = nanoseconds.
awsome ty very much oldman.. gives a hint what i do for hobby lol ... your the man of the hour.. fav bev to ya. kb2wvo
bug ya one more time olmand. i have the analog hp1740a. Sq's on screen as normal. the lil marks also .. cant rememebr how to spell that big 10 dollar word ... so if iam at .1mSec the sq's are .1 each then divid that by 5 for each sub mark on the Gline..
yes, exactly. The value on the knob refers to the large divisions, usually 10 of them across the screen. The little tic marks are 1/5 of that.
ty ty sir w2aew. de kb2wvo
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%?
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.
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?
Not really - remember a parallel resonant circuit looks very high impedance at resonance, a series resonant circuit appears very low impedance at resonance.
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
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.
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.
Your handwriting looks like Forest Mims III. Neatly written!
Thanks! I studied his Notebook series in the 1970s.
great video. thanks. Could you tell us how to measure the Q factor, R(ohms),dissipationfactor of a coil on scope please ?
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
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.
Simple and effective method . Thank you for sharing .
What is the benefit of doing it this way versus just using a ESR/Capacitance meter?
No real benefit to this method other than:
- an excuse to play with you oscilloscope
- gain some better understanding of how capacitors and inductors behave.
So, no, this method was show mainly as an educational exercise, not necessarily a more practical way to measure capacitors and inductors.
@@w2aewCool. Thanks for the reply.
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.