Inductor Tester

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In this video i show how to build a circuit that can measure the value of an inductor in conjunction with an oscilloscope. This is meant to be a replacement for my $10 LCR meter, which isn't very accurate, and has very poor resolution below ~1mH of inductance.
The circuit works by sending a single pulse through an inductor, which has a known capacitance in parallel with it. When current through the inductor is shut off, the L-C pair "rings" at its resonant frequency, determined by f = 1/[2pi*sqrt(LC)]. Since frequency "F" and capacitance "C" are known, the inductance can be determined.
Current through the inductor under test is limited by current limiting resistor(s), which are manually configured by toggle switches. By default, a 680 ohm resistor is connected in series with the inductor, but 220, 100, and 10 ohm resistors can be toggled as well to allow more current for the test pulse. This is because smaller inductor values need to be pulsed with a larger current to generate a readable "ringing" signal, due to their lower energy storage for a given current.
In addition to multiple resistor options, there are two capacitance values that can be tested against. By default, a 1 nF capacitor is connected in parallel with the inductor under test, but a 47 nF can be added in parallel by toggling a switch.
If you don't have an oscilloscope, it may also be possible to measure frequency using a high impedance AC coupling to a schmitt trigger which would send square wave pulses to an arduino or similar microcontroller to be measured.
This is a valuable addition to any power electronics toolkit, because inductors/chokes and transformers are used so often, and knowing the exact component values is crucial for design optimization.
However, if you're only looking for something to give you a rough approximation of inductance / capacitance, the cheap amazon/ebay LCR meters will still get the job done, and I've used this one for several years:
www.amazon.com/AITRIP-Transis...
Automatic coil winder video:
• Automatic Coil Winding...
Music Used:
Lakey Inspired - Chill Day
Lukrembo - This is for you
Kevin MacLeod - Lobby Time

Опубликовано:

4 авг 2022

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Комментарии : 149

@FodderBoi Год назад

Impressive electrical engineering skills. I wish I had half the ability you do.

@martinkuliza 2 месяца назад

Don't wish.......... KEEP PRACTISING AND LEARNING one thing i see a lot of with beginners is I WISH i knew this or that or whatever. Forget Wishing, Pull shit apart and learn what you can and if you don't know.... ASK US I suppose another thing worth mentioning is.. - Remember everything starts as 1 BASIC CIRCUIT - Then we add a circuit to that circuit to give the first circuit added functionality and before you know it we have massively complex circuits Look at his schematic again, Step by step and imagine it as separate circuits and you can actually build those separate circuits and test them so you understand what each stage does, after you do that (which will likely take you 2 weeks) YOU WILL WISH NO MORE :P

@wa4aos Год назад

Glad I found your channel. As an engineer, we know, no one knows it all. Learning new concepts and applications on RU-vid is an excellent way to TRY to keep up. Great video, THANKS !

@crazyirishman121 Год назад

That was an excellent video. You don’t waste time. You just give all the facts. It’s great.

@rav3nx33 Год назад

Thanks for taking the time to put this out, just starting to take my inductor understanding higher; and this helped a lot. I will be building this, Ta!

@jakobhalskov Год назад

Very well explained and pleasant to watch :) Looking forward to follow your future projects!

@Leezorc Год назад

Brilliant. Very simple and elegant. Great Thanks for this project!

@martinhorner642 Год назад

Amazingly, I have been looking for exactly this video for quite a while now. Thank you.

@jupiter909 Год назад

Fantastic insights into your builds, thanks!

@coderhex1675 Год назад

I encounter your video and this is the most usefull project i have seen on the electronics channel.

@djisydneyaustralia Год назад

Very smart guy, thanks, your explanations gave me some insight as to why some components are used in unrelated circuits

@chronobot2001 Год назад

Excellent video. I particularly liked the explanation on how to make an scr out of a npn and PNP transistor.

@AhmedSherif-mn8gu Год назад

This is gonna be on my list of home-lab devices ! Subscribed !

@roboticus3647 Год назад

I recently stumbled across you channel. I'm happy to see another channel for technophiles! I got to this vid through your two-stage refrigerant project. I don't know anything about hvac technology, so it'll be interesting to see the progress for your LN generator.

@t1d100 Год назад

Super interesting and useful. The latch method is very clever. All very cool. Thank you for sharing.

@isururanaweera376 Год назад

Thank you very much. Learned a lot of valuable information. I appreciate the effort put into explaining it so simply on video❤

@newburypi Год назад

Nice video. Tagged it for the next time I expand my tool set. If anyone decides to go with arduino the could likely add some front end functions. One button test (no need to switch the tester on and to arm it) and a timer to disconnect the battery after a few minutes of idle time. Thanks again.

@trevorhunt6083 Год назад

Excellent video.. concise and very informative.. thanks 👍

@alocin110 Год назад

Your vidoes and experiments are the best. Your knowledge about the electronics is so superior and the way you tackle the problems and find the issues are amazing. I love to watch your videos and it really a great learning channel. I subsribed to your channel and enjoy watch the clear ideas and implementations. Thank you for sharing. You are the best on YT>

@arniesneider7163 Год назад

Love your channel, it's all the stuff I'm interested in:)

@failvail2399 Год назад

Man I just found this channel, thank God

@papalevies Год назад

I love these homemade lab equipment projects

@weldit1251 Год назад

Just stumbled across your channel.... You're awesome bro. Good work!

@JohnUsp Год назад

Awesome, please, continue doing videos like this one.

@NeonblueIndustries Год назад

Wow! Kick ass Bro! Thank you! Great videos!

@BlondieSL Год назад

Nice. What I really like, beside the circuit, is how nice the box printed out. It looks like you also print on clear glass (no texture). I do the same thing because on the cases I design, I like the ultra smooth faces rather than textured. Plus, my "textured" bed glass got all chewed up when I first got this crap printer. LOL The extruder dug right into it and slid across the surface, creating a trench. So that would mess up a textured-look face. The other side of this particular bed also has a different texture, but the glues and stuff I've used are so embedded into the texture that nothing I do removes it. Not even Isopropyl alcohol. LOL So yeah, smooth faces on cases are excellent. A suggestion for a future video would be in fact adding an Arduino to this, with the math and code. Personally, I use Nextion displays as they are a wondrous screen. You can code right in the display itself as well as create the most amazing "pages" with many objects on them. For Arduino to send (or receive) data to/from the display, is not load heavy at all. Plus, one does NOT need to use the horrible Nextion libraries!! Anyway, this might be a nice complete project that would look amazing and reduce switches to only the power switch. Yes, the Nextion has "soft buttons" that can be sent to Arduino to do whatever the physical buttons were doing.

@marcosdalmeida6629 Год назад

Very nice video, especially for the ones like me that are starting :)) Very well explained, thanks a lot

@tonygomes6306 Год назад

THIS ONE IS GREAT... THANK YOU

@ukaszlipski4663 6 месяцев назад

I love to learn things like this.

@vobinhthu5299 Год назад

This project is very good!

@awesomecronk7183 Год назад

For the electronic output, maybe "amp it then clamp it"? Boost the voltage so that small ones get captured, then clamp it with zeners so it still can't exceed the 5V limit.

@liveen Год назад

at this point you'd have to introduce something to compensate/filter noise as well though, which in itself means more control there as well. It's a good idea though, but I get that the creator wanted to keep things a bit simpler, even though it means less accuracy. Easier for us plebs to understand while also being something that won't be too complicated to maintain

@lalogarcia6686 16 дней назад

Excellent video!!

@moustafaesber3690 Год назад

Very beautiful and important video

@SC.243k Год назад

Great work

@koalabanana1998 Год назад

very useful might try building one

@Mike__B Год назад

Man I would have loved this when I was teaching an E&M lab class, we'd do one experiment with an RLC circuit and we'd power it with a square wave and try to find the inductance but regardless of what setup we'd use the inductance measured from the time constant decay would have discrepancies from the measured inductance based on the cycle frequency and could never figure out which one is "right" because the inductors have been in the department for years were theoretically "20mH" but without knowing trying to problem solve why I always got discrepancies was impossible.

@CNCmachiningisfun Год назад

Perhaps you could use the LC tank circuit as the phase shift element in a PLL, thereby automating the frequency extraction process.

@TheBypasser Год назад

Nice, although afaik there is a frequency shift due to the oscillations decaying in amplitude. I usually go with the "frequency-sweep" approach, that is sweeping the frequency on a series RLC while looking for a peak voltage across the resistor.

@Yorumcu63 Год назад

Great video

@ebarbere Год назад

Great channel.

@EJEuth Год назад

Very interesting your device/tester. If possible, I would like to see a continuation, probably using an add-on in the output. I guess those clamping diodes you have mentioned would shift or dampen the oscillation too much, and most jellybean Op-Amp would not work. Instead, I imagine a simple stage of most signal BJT transistor (HFE > 100) could be used to decouple & perform the saturation/cut (probably 5~10x gain), while sending its output to a frequency meter function of a DMM, for instance.

Год назад

you're a GOD

@niknam. 5 месяцев назад

many thanks buddy!!!

@Debraj1978 11 месяцев назад

One important point: The waveform that we observer on oscilloscope is the "damped" waveform. And damped waveform frequency is not same as the resonant frequency. Resonant frequency = wn = 1/sqrt(LC) Damped frequency = wd = wn*sqrt(1 - zeta^2) And zeta = (R/2)*sqrt(C/L) Overall, is the resistance of the inductor is significant, you can still calculate the L value by measuring the "R" separately and making correction to the damped waveform. That way, you will get better accuracy of the inductance measurement.

@wizrom3046 Год назад

I would have preferred a free running oscillator where the freq is based on the test inductor. Then a microcontroller could take a freq measurement over a long period like a couple of seconds, and then give you a quite accurate inductance reading on a little display.

@peterschets1380 Год назад

Also add noise.

@Robothut Год назад

You can make a Latch with the remaining Inverter gates as well, reducing the parts count of the design.

@Debraj1978 Год назад

I am exactly making this for measuring the transformer inductance. There is a similar video from "Diodegonewild". He uses the setup for Q-factor measurement to find coil short on transformer.

@anthonywilliams7052 2 месяца назад

You could do a frequency sweep for an estimate, then resweep in the range where you saw resonance for more accuracy.

@nf4x Год назад

Your slow turn-on may be due to browning out your HC14 STs. They can source or sink 4mA, so at 5V you need like 1.3K Rg to keep the current in range. You might experiment with this a little to see if things improve. Otherwise another gain stage or gate-driver to allow a higher gate current will improve the situation / get you past the miller plateau faster.

@seanchallenge Год назад

Awesome 😎

@SteveWard Год назад

Keep in mind some frequency-related effects for core materials. For instance, the powdered iron core loss might be worse than the 1nF cap at ~500khz. Also, solid steel slug cores will have large eddy currents, especially at 10s of kHz. Maybe worth trying bigger capacitors to lower the testing freq? My quick and dirty method for measuring high power inductors, especially over wide range of current or flux density, is to apply a fixed voltage pulse to the inductor from a low impedance source, could be large electrolytic cap, with a mosfet and measure the current response during the pulse with a current transformer or shunt or hall-effect sensor. For instance, 5V applied to 1mH gives a current rise rate of V/L = di/dt or 5A per millisecond (keep the pulses short!).

@HyperspacePirate Год назад

Good advice, thanks. I did notice a slight discrepancy in inductance on the 1nF vs 48 nF caps with certain core materials, so i guess that explains it

@denz37 5 месяцев назад

Can u made tutorial of it

@lavy9740 Год назад

Hey man great project! I have a question about your toggle resistors. Since the 680 ohm is hardwired, when you toggle a different resistor wouldn't the resistance add to the 680 in parallel? For example, with the 220 switch flipped, the resistance of it paralleled with the 680 would be around 166 ohms. Does having a precise resistance value there not matter or am I missing something? Keep up the good work btw, I love analog electronics and I'm working towards my EE. Guys like you are a great inspiration and help me gain a better intuition for circuit design. Love.

@koharaisevo3666 Год назад

Yes it would be added in parallel but the value of the resister isn't important it just change the amplitude of the oscillation and make it easier to measure, what you care about is the frequency of the oscillation.

@taylorboultinghouse8296 Год назад

Yes, adding the other resistors in parallel with the 680 ohm resistor drops the overall resistance. This is because as the inductors get smaller their response to the smallest current (from 680 ohm resistance) decreases. The parallel resistors allow for the current to be increased and therefore increasing the amplitude of the frequency response. I hope this helps. I'm pursuing a BSEE as well. Cheers!

@lctrstone8302 Год назад

That's what I noticed

@xhunter3437 Год назад

Nice🔥

@proffesor4709 9 месяцев назад

6:51 if u have always connected the 680 ohm resistor and u connect another parralel resistor, doesnt the resisteance decrease?

@boonedockjourneyman7979 Год назад

Very good.

@barbasbandas6665 Год назад

Great video. How about continuing the arduino measuring thing? Maybe add an lcd screen too. It would be awesome and you could even try to sell a kit. Cheers!

@Basetonic Год назад

Nice video and I like the project! But SCRs are Silicon Controlled Rectifiers, not Relays.

@Dragonrider616 Год назад

Loved the video, but what pins did you use on the schmidt trigger?

@StormBurnX Год назад

This makes me want to compare a transistor latch vs an optoisolator-based latch

@_tiredofidiocy_ 15 дней назад

There is simpler method. Just apply step voltage to inductor for short period of time and measure speed of increasing of current in the beginning of transient dI/dt. The inductance will be calculated as Voltage / (dI/dt). Using this method you can also observe how the inductance decreases while current rises and dI/dt also increases (meaning current rises faster). You can measure saturation current which is important for power applications using this method.

@roganthoerson1909 7 месяцев назад

khz still seem to be on the high side for measuring with an Arduino no ?

@tnt-hv6qw Год назад

very cool thank you

@sayedroni7035 Год назад

Thanks

@terrymay2970 Год назад

I enjoyed your project and plan to try to replicate it. Also liked the project box you used, could you provide a source, or at leat a brand neme?

@jamescollier3 Год назад

nice!!

@EasyOne Год назад

nice

@andrewdoherty737 Год назад

SCR - silicon controlled RECTIFIER

@mohinderkaur6671 9 месяцев назад

Nice build. Why not add a microprocessor to automate it and directly display the inductance? And Arduino or PIC should be ok and 20x2 or 16x2 lcd

@mohbit3336 Год назад

Hey can you use it to measre inductance while transformer or inductor in circuit ?

@acmefixer1 Год назад

It should be possible to use some of the unused inverters to replace the two transistors. The 1N4148 diode has a breakdown voltage of 75V *minimum*; my guess is that the actual value is above 100 volts. Also the diode in the MOSFET should protect the device. Thanks for the interesting project. My one drawback is that I don't have a 'scope that gives measurement of waveforms so I wouldn't be able to use this project.

@shauni_jade Год назад

you still can use the time divisions to eyeball the time between peaks and calculate the frequency as 1/T

@acmefixer1 Год назад

@@shauni_jade I've measured many inductors by paralleling a capacitor and finding the resonant frequency then calculating the inductance. It's simpler than measuring pulses, and with a signal generator or receiver it's more accurate.

@mohbit3336 Год назад

Hey I looked up the IRF540N RDS-ON =40milloohms so the maximum current that the LC circuit can draw in while charging up the LC circuit to store energy in case of 10ohm resistor is 4.5/(10+0.04)=0.432amps I hope this is correct since I'm designing a similar circuit to your's thanks any way your design is so helpful I used the oscillator part but with lower Mosfet RDS-ON =2.5 IRLB ohm

@joejane9977 4 месяца назад

great fun

@willyrivero470 Год назад

Great video, thanks! Would you be so kind to tell me where do I have to connect the oscilloscope probes?

@HyperspacePirate Год назад

I probe the anode side of the diode connected to the MOSFET

@willyrivero470 Год назад

@@HyperspacePirate Thanks so much.

@cosmiccashcosmiccash8358 Год назад

Change the world!

@dandan-gf4jk Год назад

Now do a capacitance meter! But for reliable pF measurement

@xtevesousa Год назад

There are inductor testers that detect shorted turns by the much higher damping, Could you do a test adding a shorted turn to see how much it effects the ressonance frequency?

@JosePerez-il5qy Год назад

Great video. Thank you for that. Can you do a similar circuit, but instead, to detect the most efficient frequency to be used in an unknown ferrite core? Since there are different composites for ferrite cores, not knowing the specifics will not make it easy to choose the frequency to be used in a switching application. You would need to try from several tens of kilohertz up to maybe 1 MHz. A circuit to determine the most efficient frequency will certainly be VERY handy.

@liveen Год назад

Could have something with software, maybe? Like a program controlling a mosfet, measuring the ringing and stability, and doing a sweep across a large frequency range automatically? With the speed of electrons and components in circuits, this could be something only limited by the clock speed of the processor of the program

@JosePerez-il5qy Год назад

@@liveen Hello LiVeen. Thank you for your suggestion. Yes, using a microcontroller is a sure thing and as you said, sweeping a specific frequency range. About the uProcessor clock, I use a PIC microcontroller using from 20 to 40 Mhz and they cover the range very well. The measuring part is the one that I am asking for. You know, how to determine the best frequency out of the measures over the frequency sweep. Since I was thinking about custom switching power supplies, I had the idea to measure the combination of voltage and current produced by different frequencies but I was asking to see if there is any better idea around for determining the best frequency for a specific ferrite core.

@liveen Год назад

@@JosePerez-il5qy well from what I remember the resonant frequency is a big deal in ferrite efficiency. I can imagine that if you manage to find the resonant frequency at a low frequency, you could for example be safe in using an exponent of that frequency (like 10 times higher for example) while keeping the correct ringing, just at a higher rate, kinda like octaves in music. A C1 and a C2 are the same notes, just with exponents on the frequency, achieving the same general resonance between them. So the same is probably true with inductance. If so, you could probably figure out what qualifies as the best resonant frequency, what things are measured, then implement that with a low frequency range (so its easier for a simple board to pick up through noise, and then for the actual real-world example, you multiply the frequency and there ya go. Obviously, since this would be low frequency, it would get you to the general area of where the resonant frequency is, when used irl, but it would at least be a start. BUT: I dont really know exactly what methods are used to figure out the right frequencies, so I wouldn't know what things to measure and what filters etc are necessary

@gonzagaribotti9852 3 месяца назад

"I built the circuit , but I have a problem. The pulse enters the gate of the MOSFET correctly, but when measuring at the anode of the MUR120G diode, the pulse is inverted. The MOSFET I used is a 3N80C with an RDS on of 4.8 ohms, instead of the RF540 which has an RDS on of 77 mohms

@alloverflorida5886 Год назад

Noice!

@Tr0nism Год назад

6.9 nice!

@indianinventionboy Год назад

#nice_video

@ZeekSuds Год назад

Build any synthesizers? This type of thing would make some good analog wave forms

@HyperspacePirate Год назад

i've definitely thought about it. Not really a music guy though

@edwarcastro4590 Месяц назад

I don't have a oscilloscope or arduino what can I do to check the value of the inductor?? I would appreciate your suggestion.

@Space_Reptile Год назад

i would love a followup where you show off the "scopeless" readout method

@csu9242 Год назад

Consult ebay and look for a Belco LCR bridge, the better one has an additional poti for defining the coil-Q, but it’s hard work to work with ..

@alexloktionoff6833 Год назад

Actually, you could make a latch /*actually RS trigger*/ from two spare Schmitt triggers elements and resistors! The transistors could be better used in MOSFET gate driver to make ON/OFF edges sharper and not overload Schmitt trigger.

@gallium-gonzollium Год назад

7:35 “6.9x higher to be exact” *nice*

@PureCoKayne Год назад

Sir is there any chance you could use another music backing track? It's the same one used in Kerbal Space Program when you're in the build editor. I'm purely asking because hearing it makes me impatiently look away from your videos at my main monitor CONSTANTLY thinking I've left the game open. Fair enough if not but oboy edit : wait this video's is different! This one's okay! To be specific, it's the backing track at 9:20 of your 5000V Power supply, or the one played at the start of the magnetic remote control video.

@abdelghanisiradj3026 Год назад

Please can you make an electronic circuit that can calculate inductance without an oscilloscope

@AnalogDude_ 11 месяцев назад

VERY Cool, but how about CD4053? or CD4066 or ADG419 and CD4044 S/R latch / CD4013 flip flop?

@ethanmarlatt797 Год назад

Video has been up for awhile, but thought I would ask why you used the Schmitt Trigger output to drive a MOSFET instead of just using the pulse that it generated?

@HyperspacePirate Год назад

making sure there's no repeat triggerings from switch bounce

@ethanmarlatt797 Год назад

@@HyperspacePirate I was under the impression that the transistor latch circuit was meant to eliminate switch bounce, is the MOSFET just an extra precaution?

@HyperspacePirate Год назад

@@ethanmarlatt797 theoretically the peak current could be really high so i didn't want that going through the small switch or tiny BJTs

@ethanmarlatt797 Год назад

@@HyperspacePirate Ah okay, thanks for replying! Looking forward to next update in your cryocooler series!

@zim2493 Год назад

What is the suitable pulse duration time?

@csu9242 Год назад

This resonance- and triggermode ist good for bigger inductors. But for amateurpurposes in micro and nanoranges only a well tested LCR Wheatstonebridge is fitting, but Nanohys are difficult to define and the potis of such a bridge are often scratching and to find the zeropoint is annoying. And bridges in multipurpose digitalmeters are failing for coils having to work up to 200 MHz for amateur applications, ie cristall oscillators. And to take the PLL or freerunning oscillator mode you need a perfect working microwave osci with a range over several octaves and a frequency counter synchronized by gps or dcf77. And then the Thomson formula has to be transformed and your sunday is over ..

@subramaniamchandrasekar1397 Год назад

Where can I buy that miniature push button on the test jig? Need to replace one in my transistor tester. Regards.

@Dragonrider616 Год назад

They're really cheap on amazon. I got a set of something like 150 or so for about 10 dollars (approximately).

@charanvemula2623 Год назад

Sir,can you make a video that represents how electricity is produced from tidel weaves

@swp466 Год назад

Nice video, except the R in SCR stands for rectifier, not relay...

@sayantanmaiti2513 Год назад

why u didn't used 555 for pulse generation??

@Aboudy1989 Год назад

I wish you would try to replicate don smith resonant transformer and make some useful energy out of resonating transformer

@idris110 Год назад

Make Inductor tester : Step 1: own an oscilloscope Step 2: video *_*

@Dc_tech386 10 месяцев назад

So you mean to tell me all ferrite core have it’s own operations frequency to get good power results

@patrickbennett4043 Год назад

Are you planning to make a flyback transformer?

@neail5466 Год назад

Why just don't use microcontroller triggering? Don't get me wrong it is always better to know the way, still a mc can reduce the bulk. Are there any inherent limitations I am missing out?