#247

[@WaltonPete]

Great explanation of the circuit - succinct and straight forward without unnecessary waffle! I appreciate the use of the scope to illustrate the voltage differences within the working circuit. I defy anyone who doesn't find your style of explanation accessible and informative. Too many electronics enthusiasts on KZbin waffle and fail to put things in such an understandable way. Thanks.

[@w2aew]

Thank you, I appreciate your nice comments.

[@purza95]

I love your use of the helping hands to hold the schematic! I love these circuit descriptions, or as I call it "Psychoanalyzing the circuit designer".

[@jasoneyes01]

Alan, always had a hard time visualizing circuits till now. Thanks. Your system makes learning very easy.

[@fieldsofomagh]

Looks a very efficient meter that won't cost an arm and a leg. The best are always the simplest. Great explanation and thanks for sharing.

[@TheRadioShop]

I like this circuit. Think I will build a through hole version. Thanks for the circuit description Alan.

[@rpsproject5349]

Great little circuit, I'm very interested in that oscillator circuit using transistors that's really nice.

[@TheRangerDale]

Thanks Alan, like always very understanding what is happening in the circuit.I to have one here I use but now I have a better understanding whats going off in the circuit your very easy to follow.73's Alan

[@andr27]

one of most informative youtbe channels. Its unbelievable how easy and simple way you can explain all this electronics matters. I know this is not profitable but I would like yo to post more explanatory videos. Thanks! :)

[@EdEditz]

I build this 10 months ago (see earlier comment) and it's just awesome. It's become a very useful tool in my little electronics lab. Because I re-use a lot of components I solder out of old equipment, this meter has become the go to tool to check if the caps are ok.

[@svsv9]

Hi, I am very new to electronics, I've seen this project built with all ceramic cap, and some with Electrolytic and 5 ceramic Caps. I don't know which one to order and the voltage of them. I know it will be working with 9 Volts regulator but I can't find 16v to say something in my local store. only 50volts minimum value. May you light a little please. Which uA panel did you use it? and resistance for that? did you remove the shunt resistance in the uA panel?

[@EdEditz]

@@svsv9 You can use 50V. The higher voltage rating is only better. I can't comment on the meter I used because I re-used an old zener diode tester. It has a big analog meter and the case was just the right size so I built it into that. I know it doesn't have a shunt resistor, at least not outside the meter. It just had two leads that I connected the print to. Any capacitor over 1µF will be electrolitic. For the smaller ones you can use ceramic caps.

[@svsv9]

@@EdEditz Thank you so much. I was about to make an incorrect order. I opted for 50uA and 10 k Pot. and some sort of resistance to test and calibrate because I don't understand the formulas to get the total Resistance. but I will find a way to figure it. Thank once more. It's ok if I face problems ask you again?

[@EdEditz]

@@svsv9 Of course you can ask any time. If I can, I will help you :) Mind you, I am no expert! I've been doing electronics for 30 years but I'm not educated in the subject. But I have picked up a lot of knowledge along the way. I have a website on which I have electronics projects to build your own synthesizer. I don't know if that's your thing but here's the address: www.eddybergman.com/ What I mean to say is, I get a lot of questions from people who build from my website so I'm used to answering questions. So it's no problem ;-)

[@mikesradiorepair]

Nice simple circuit that looks to work well. Thanks for sharing. Mike

[@tonybell1597]

Excellent explanation, thanks. Off to the breadboard!

[@myenjoyablehobbies]

Thankyou, very well explained, I have a good understanding of the activity of the components in each block, thanks to your very well explanation of each block in the system.

[@EdEditz]

This is a cool circuit! I just finished building it on a breadboard. I didn't have schottky diodes but I used some Germanium ones with a voltage drop of 270mV and they worked fine. I have an old broken Varicap tester with a 40µA meter inside which is ideal to house this project in. Excellent stuff. It'll give me something to do over the weekend ^____^

[@w2aew]

Have fun with it! Hope it fits nicely in the old tester.

[@EdEditz]

It does. Like it's made for it :)

[@yekoof]

Great breakdown and description of the circuit! Excellent walkthrough!

[@dentakuweb]

Interesting oscillator I'll have to look through my collection of old meters now too.

[@dasolpan3194]

I like the way you explain, Thank you. I will try to built this DIY ESR

[@EJEuth]

I revisited this video, again, and if I could I would give more thumbs up 👍 than just the first one.

[@g0fvt]

Another excellent video, always thought provoking!

[@mashun-o4d]

Going to make this one!

[@realpower9ir]

Thank you and hats off for clear explanation. just maybe a short explanation on feedback circuit on C5 toward Q3.

[@w2aew]

It really isn't a feedback path. C5 is coupling the output of the oscillator Q3 into the base of Q5.

[@cosmicray007]

I don't know why but 7:15 hit stuck me as funny

[@Gonzi-ze1sk]

I always enjoy your videos.

[@PapasDino]

Great explanation Alan...sorry it took so long to comment but something screwy is going on with KZbin's new video notification system. If I didn't already have one I'd build this one up but I will pass the info around to our tech interested club members. 73 - Dino KL0S

[@amciaapple1654]

What a simple circuit...yet it does so much! Also, could you do a Back-to-Basics video about Ferroresonance? No the LC resonance but Ferroresonance as Wikipedia describes it. I have never seen anyone showing it occurring.

[@Stefan_trekkie]

I was looking up for nice design to build up. This is simple and easy to put in but need a analog uA meter. neat none the less

[@SSCPWS]

Terimakasih bang tutorialnya bermanfaat sekali

[@supyrow]

Thanks for sharing this Alan. gonna have to build this up.

[@extoprak]

I do not know whether it is a good idea or not, but how about replacing the oscillator part with an 555 oscillator so I can test the capacitor under different frequencies? maybe I can place several capacitors in parallel and use a switch to select in between, in this circuit too.

[@CarlosAndresEsparza]

Hi Alan, thanks for the clear breakdown of the circuit, very helpful. I just have a doubt, if I have a 30uA analog display, do I need to make some adjustments to the circuit? All the best mate.

[@jeremyp7293]

With a 100uA meter I did not use R24. The only adjustments you will have to make is going to be R24 I think.

[@KingOfTheGrailCup]

Hi. Big thumbs up to @w2aew. I see that Alan used 10nF (C3) instead of 22nF as per the circuit from the EEBlog forum. Are these values non critical? If I am attempting to use a 30uA meter I reckon the resistors R15-R20 can remain the same but with trial and error choose a higher value for R24. Do I need to be looking at signal attenuation through C3 and C8 too? Thanks for any insight here.

[@budude2]

Perhaps I missed it but was is the frequency of the oscillator circuit? I know with my ESR tweezers that you choose higher frequencies to get more accurate ESR measurements so was just wondering if the frequency could be increased to enhance its accuracy?

[@mrjohhhnnnyyy5797]

About 90kHz, the sweep was 2uS/div 10:25

[@stargazer7644]

Brian Ullmark the scope shows one cycle of the waveform to be 5.4 divisions, so at 2us per div, that's 10.8us, and 1/10.8=92.6 kHz. You could vary this frequency by changing the capacitor value in the oscillator, but if you vary it too much you might need to tweak some other components farther down the circuit also.

[@w2aew]

You can also see the Trigger Frequency readout in the lower right corner of the scope display.

[@jojotech4615]

Sir Nice tutorial

[@mrjohhhnnnyyy5797]

Nice little circuit. But I have a feeling that if you don't match Q4&Q5 by Vbe, the performance won't be that great. Did you pick a matched pair or just a random couple? And yes, the oscillator is quite a neat little circuit, the waveform looks good for such a simple arrangement running at 90kHz

[@w2aew]

There is enough degeneration in the CE amp that the small mis-matches won't affect things in a dramatic way. I simply picked a pair out of a random 2N3904 bag...

[@mrjohhhnnnyyy5797]

***** That's great, makes it real easy to get going

[@EJEuth]

I believe this circuit, with central reading at +/- 3R, is even more sensitive than another famous one, based on the Quad OpAmp TL084.

[@gilberto5018]

Parabéns pelo seu vídeo muito bom. Por favor pode me enviar por e-mail, diagrama electrico, layout da pcb e lista dos componentes eletrônico, muito obrigado

[@w2aew]

I'm sorry, I do not have a circuit board layout for this design. Check the EEVBLOG link in the description, maybe someone there has created one.

[@pirateman1966]

Very elegant.

[@gilberto5018]

Onde comprar um exemplar deste transistorizado

[@carlospeart6578]

Hi good day: Can you tell me if there is a diode to replace the 1N5711? Because I can't find it here.

[@w2aew]

Just about any small schottky diode will work.

[@geoffturner4018]

Alan, Great video as usual. Just a note about the very simple oscillator used in the circuit. I use it all the time for my projects all the way from simple 1 sec pulsers to 100 kHz circuits. I found it in the Tektronix 7603 oscilloscope Calibration pulse generator of approx 1KHz. Geoff.

[@ko2fjb]

I built the ESR meter in April 2014 QST. I'm curious about the performance of this unit compared to yours and the one you just went over.

[@w2aew]

I haven't looked at the one from QST. This circuit and the one that I built years ago perform similarly.

[@reproeletronicos1309]

Oséas Medeiros HELLO SET UP THIS PROJECT, BUT THE POINTER DISPLACES 2 CENTIMETERS OF THE INFINITE SCALE IS THAT BECAUSE I AM USING A 95W AMPERIMETER AND AN OLD KAMODEN 104B MULTIMETER THANKS FROM THE COOPERATION OF ALL FRIENDS

[@GaRbAllZ]

What frequency does the oscillator run at?

[@w2aew]

approximately 100kHz

[@jonathanhughes380]

Hello, I have a question. After watching your video i found the plans And build one on my bread board. After a few tries I got it to work, and it seems to be doing everything your build did. My question is I have a 2-3 uA of current showing on the meter when i turn it on with leads open. did your build act the same im using a 1.5% 0-50 uA meter. after reading all 10 pages on the EEV blog. I thought i was having a problem with Cap 3 in the circuit, but it is on spec @ 10n , I changed it to 22n. little to no change. any Ideas? thank you Jonathan.

[@w2aew]

It is likely that the gain of the two common emitter amplifiers on either side of the meter network isn't matched.

[@jonathanhughes380]

@@w2aew thank you very much that makes a lot of sense just like a vacuum tube amplifier that has two matched 6f6 output tubes. Thank you.

[@yoramstein]

Nice video again

[@amarinato]

Oi... sou leigo no assunto, mas montei circuito e as tensões estão iguais a que vi no seu projeto. Porem meu amperímetro não oscila. Qual a tensão entre o TP3 e TP4? Pode me ajudar? Apenas para testar o circuito, no lugar do amperímetro, se eu colocar um multímetro digital qual a escala que eu uso? desde já agradeço.

[@ohmslaw6856]

Great video. Can you explain how Q2 is being turned on again.. I understand that while Q1 is turned on the base of Q2 should be around 3.76V, that being the collector voltage of Q1.. so wouldn't the cap on the right side only have to discharge to around 3V to begin conduction of Q2.. I don't understand why it discharges to 2V instead.. please help, thanks

[@DavidLeeMenefee]

I learned a few things here. Thumbs up........PEACE

[@0MoTheG]

I did not understand the central point of it: How does it make the distinction between Z and R ?

[@alanwolke6253]

The test frequency is high enough (~100kHz) to make Z quite low (0.15 ohms for 10uF cap), so the reading is dominated by ESR.

[@PelDaddy]

Thanks for sharing and explaining the circuit. I finally started looking not at the voltages applied to the EBC of transistors but to the *differences* between those voltages, and the effect of those differences on the junctions. Now transistor circuits make a lot more sense. What effect would a more sinusoidal wave vs. the square wave have on this circuit? I just might try...

[@w2aew]

It would work just as well, I think.

[@PelDaddy]

w2aew Thanks for the reply. I was wondering more what effect a sine wave vs a square wave would have on the ESR measurement. Do the harmonics of the square make it different? Curious from an educational standpoint. Easy enough to test, I suppose.

[@trickedouttech321]

Great video. It's a nice little ESR circuit. I know it's getting up there in video years. However. I will attempt a question anyway. Can you clean up the overshoot or oscillation transition spike on the DC rail. or is that inherent to the transistors being used. If you can clean it up, would it be worth the effort, would it make the meter a tad more sensitive or steady? I would think that a small steady Pulse - + spike in the DC signal would cause small deflections on the marker needle, causing it to oscillate when using a high res meter like a 0 - 50uA / 0 - 100uA meter, ??

[@w2aew]

Those spike are so short in duration, they won't affect the readings at all.

[@robthorn3910]

Looking at the oscillator, how did you determine that the transistor Q2 turns off? The scope seems to be showing about a 1volt swing. At full on the emitter should be about 2.6 volts (and the collector also) and adding a volt shown on the scope puts it at 3.6 volts rather than going to 5v. Does this make sense or am I missing something?

[@w2aew]

The missing piece is that I didn't show the base voltage of Q2 (collector of Q1). However, the evidence that Q2 turns off is shown in the CH1 trace, the collector voltage of Q2. It rises to 5V, indicating that there is no collector current. Note that the vertical position is adjusted to 3 divisions below the midscale (note the indicator on the left side of the screen). The voltage swing on Q2 collector is being limited by the base-emitter drop of Q3.

[@taojiang719]

thank you sir

[@EJEuth]

Comparing your experience, do you believe your original / first circuit is simpler and still worth for someone else to give a try on it? Could you share it? Thank you for sharing these videos!

[@SuburbanDon]

Do you think 1N914/1N4148's and any Schottky diode would work ? Thanks.

[@w2aew]

Yes, D1 and D2 are just there for protection. Basically any Schottky will do for D3 and D4.

[@GlennPierce]

Why do the two voltage dividers at the start of the bridge circuitry have different values. Ie R11/R12 versus the lower values R8/R10. Is is to allow for extra current through the tested capacitor ? Thanks

[@w2aew]

Yes, considering that the ESR would be a few ohms or less, these resistors needed to be smaller.

[@marks6292]

Alan, what happens if one of the resistors in the bridge goes out of toleranance ? How would you know? Or, does R23 adjust for such a bridge anomaly?

[@w2aew]

If the bridge gets out of whack, then you'd see a small meter deflection even with no capacitor installed.

[@kevinsmallman3116]

Hi again, I'm going to have a go at building this in the powered breadboard first. For the panel meter, there is one I'm looking at on eBay UK that's 1900 ohms meter resistance - would that be an acceptable value for this? It looks from the circuit you adjust it for FSD with some additional series resistance plus a 10k trim pot, which is modelled as 20K - is that right?

[@w2aew]

that should work

[@kevinsmallman3116]

Yes indeed it does for me. One thing - when the oscillator is open circuit, i.e not driving the rest of the circuit, it's output is bang on 100khz with the 15n capacitor. When I connect the rest of the circuit, it makes the square wave nice and symmetrical, but the freq drop to about 87khz. I guess it doesn't matter much, but it was just something I noticed.

[@w2aew]

@@kevinsmallman3116 Interesting, I didn't notice that on my circuit, but it could've happened.

[@jeremyp7293]

I made the circuit and it work well. I used a 100μA meter so I did not use R24 only the 10K potentiometer. now I need to find a box to complete the project. Here a picture of it: www.flickr.com/photos/188548216@N02/50916240413/in/dateposted-public/

[@w2aew]

Nice build!

[@slimharley8692]

I didn't see electrolytic caps called for on the schematic, yet you used them on your breadboard design. Could you share your reason and placement of these caps? Thanks for your very informational videos.

[@w2aew]

I used electrolytics for C4 and C6, the degeneration bypass caps for the two common-emitter amplifiers. I didn't have any non-polarized caps that were 2.2uF.

[@jay_diddy_b4772]

The ESR of C4 and C6 should be small compared to the 33 Ohm resistors in series with them. By small, less than 1/10 of the value, so less than 3.3 Ohms. You can make the capacitance of C4 and C6 larger if you need to achieve this. 22uF or 47uF 10V electrolytic should work fine. If the ESR is large it will reduce the gain of the amplifiers.

[@richardgoebel226]

Thank you for posting this. Where can I find more info regarding what is acceptable ESR, borderline, and bad? Does the voltage rating of the capacitor factor into it? I am learning and appreciate good replies to my comment.

[@w2aew]

Opinions vary, and the acceptable ESR will depend on how the capacitor is being used in the circuit. However, in most cases, ESR should be less than 1 ohm or two.

[@richardgoebel226]

Thanks.

[@stargazer7644]

richard goebel the answer is yes. The higher the voltage, the bigger the cap. Physically larger capacitors will have lower ESR. Google for ESR chart.

[@richardgoebel226]

Star Gazer, thank you for the advice. I will check it out.

[@nihonam]

How do I need recalculate tie components of pointer instrument (or whole circuitry) for using 100uA graded one instead of 50uA? 20mA? I have both. Is it suitable for in-circuitry caps metering?

[@w2aew]

It's probably best to determine the series resistance experimentally, since the resistance of the coil inside the meter would enter into the equation, and most time this is an unknown value.

[@w2aew]

It only puts about 100mVpp across the cap, so it can be used for in-circuit testing. However, you always have to be mindful of parallel paths (additional caps, etc.) that might "fool" you.

[@Arnthorg]

Is it possble, theoretically. to make an ESR meter that would introduce a phase shift between two oscillators? So that if the meter was open circuit the two would be 180° out of phase and shorted in phase.

[@w2aew]

In theory, it would be possible, but probably not a simple circuit and measurement resolution could be tricky.

[@enojelly9452]

Unless I misunderstand (I'm just a hobbyist with not many years in the hobby), given that both your original and this ESR meters are both just "ohm meters", this in theory only works with capacitor values (or frequencies) that are "large", right? If I put in a cap with a tiny capacitance, the overall magnitude of the impedance will be high and the readings are effectively wrong. But I guess the frequency and resistors are just chosen so that it makes sense for the range of electrolytics? I've been wondering how the digital ESR meters that show both capacitance and ESR do it, and my best guess so far is that they look at both amplitude and phase instead of just magnitude. Then converting from polar to rectangular, effectively the real part is ESR and the imaginary part is resistance. Does that check out?

[@w2aew]

ESR testers mainly exist due to a common failure mode amongst electrolytic capacitors, which causes their internal resistance to increase. Electrolytic caps are generally large value (typically >1uF). The vast majority of ESR meters test at relatively low frequencies, so will NOT give you proper results for small value capacitors

[@enojelly9452]

@@w2aew Great explanation, thank you!

[@stevenbliss989]

Neat circuit! :)

[@siavasharash5448]

Maximum alowable shottkey diode junction capacitance please? I have 2 smd ss14 with 70pF. Acceptible or not? Those shottkey diode really hard to find I attemped to biuld the circuit and i have whole componets but small shottkey diode is a pain in my ass

[@w2aew]

This is a low frequency circuit, so capacitance shouldn't be a problem. I don't know where you are located, but Mouser.com has many of the 1N5711 parts in stock.

[@siavasharash5448]

Hah End of the world IRAN Thanks by the way

[@jonathanhughes380]

I have a question? I made a working model on a bread board. And every thing matched your Video with all your test resistors. So I etched a Circuit board and a completed it. Got a good pair of matching npn transistors for the metering circuit. I have been scratching my head All my voltage test point are on the money. I have a good 100kz 100mA peek to peek square wave on the DUT out. The tester works. and with the same meter i used on the Bread board the tester seems to be able too measurer up to a higher resistance. On the bread board 45uA was 0.2 ohms now on the Circuit board 45uA is 1 ohm. Its as if the scale changed. on the Bread board 10 ohms was 3uA. now 19 uA is 30 Ohms. Do you think i am falling into a Bread board Trap, or was it just to high resistance connections of the Bread board? any thoughts. Thank you for your video and your help with IDEAs.

[@w2aew]

Good question. I only built this circuit once, so I don't know how much variability there would be with component tolerances, etc.

[@jonathanhughes380]

@@w2aew I did change from 5% tolerances 4 band resistors to 1% 5 band. On the bread board no change. it was when it moved from the breadboard to the circuit board. the change happened. I'm trying to learn more and more everyday about Electronics but I don't understand everything. I really enjoy the challenge of building test equipment. Is this something that I'm just going to have to calibrate to a known resistance? the most accurate piece of equipment I own is a Fluke 87V DMM.

[@w2aew]

@@jonathanhughes380 Yeah, you'll just have to calibrate it with some known resistor values. The 87V is going to be more than adequate to measure the resistor values. For the low values (below a few ohms), be sure to use the Delta mode to zero-out the lead resistances of the meter.

[@amarinato]

Esqueci de mencionar usei um amperimetro de 50mA

[@w2aew]

It must be a 50 MICROAMP meter (not 50 milliamp).

[@amarinato]

@@w2aew Obrigado pela ajuda

[@alin936]

hey, do you think it will work with bc549 and bc559 transistors and also use 1n4148 diodes instead of es1j ? what is the purpose of 1n5711 ? can also be replaced with 1n4148 or 1n4007? (sorry for the noob questions)

[@alin936]

1n5819 diode insead of 1n5711, sorry

[@w2aew]

The BC549 and BC559 should work fine. The 1N5819 is probably not a good replacement for the 1N5711 - it is much higher in capacitance.

[@alin936]

Thank you for the replay, can you also tell me what change I should do so I can use it with a 1mA deflection meter?

[@w2aew]

You would likely have to scale down R15-R20 to make enough current available between the collectors to drive a 1mA meter.

[@jay_diddy_b4772]

I have looked at changing the circuit for a 1mA meter. It is tough. Alan is right you have to reduce the value of the resistors in the amplifier. You also need to increase the values of some of the capacitor. It is better to find a 50uA.

[@lingcod91]

It would have been helpful if the schematic provided by Diddy_B matched the version we see on this video. I assume they are both, basically, the same . . . but who knows since the one in this video doesn't match the jpg. image in the link. Details are important as even the smallest error can cause head-scratching or worse. [It would be nice to have those test point voltages . . . seen in RED on the schematic in this video. They must be important. This schematic has more info] Just an observation.

[@w2aew]

The schematic used in this video, and to build the circuit, is the schematic from this eevblog forum entry: www.eevblog.com/forum/projects/jay-diddy-5-transistor-esr-meter/msg933224/#msg933224

[@danielarriaga4806]

this proyect can be used in circuit ?

[@w2aew]

I generally advise against relying on in-circuit tests because surrounding circuitry can affect results. The signal amplitude is low enough that it shouldn't affect things too much, but you can still get fooled.

[@larrybud]

Do Q4 and Q5 have to be matched, or is any discrepancy all taken care of with the trimmer pots? Also, I'm just here to hear Alan say "Jay Diddy B". lol

[@w2aew]

It would be best if they were matched, or at the very least, the same type.

[@1pcfred]

Help! I've spent the last 3 weeks in a catatonic state due to my terminal OCD that I suffer from desperately trying to find R1 on the schematic. I fear if I don't find it soon I am not long for this world. It was all I could do to even post this comment. I was able to reconcile no C1 by considering the D.U.T. to be that component. Can I call the meter movement R1? Or is that cheating? Thanks. I'll just show myself out now. :)

[@w2aew]

If it helps your mental sanity, then call the meter R1 ;-)

[@1pcfred]

Now I just have to hope these low forward voltage mystery diodes I pulled out of one of my junk drawers will suffice for D3 and D4. They're close to what a 1N5711 is supposed to be.

[@1pcfred]

Now I just have to hope these low forward voltage mystery diodes I pulled out of one of my junk drawers will suffice for D3 and D4. They're close to what a 1N5711 is supposed to be.

[@MrWasim100100]

can a dmm is used instead of analog meter :) thanks for nice video

[@MrWasim100100]

nice video can i use 100 microamp full scale instead of 50 microamp?

[@w2aew]

Yes, you just might have to reduce the values of the resistors in series with the meter (R23 and R24).

[@MrWasim100100]

@@w2aew thanks one last question can i use 1n4148 diodes if not please some diodes that i can use in this circuit thanks again for your informative videos

[@w2aew]

@@MrWasim100100 They really should be small signal schottky diodes.

[@terencekaye9948]

I'm wondering what the highest voltage capacitor value that this tester will test,, Is it only for Electrolytic caps and not film caps?

[@w2aew]

The voltage rating of the capacitor doesn't matter. Testing for ESR is typically only done for electrolytic caps. Film capacitors don't suffer from elevated ESR as they age.

[@terencekaye9948]

Hi Thank you for replying to my question,,, So if you Test a 500 or higher volt capacitor,,, That circuit will give a ESR reading,, So then if one where to look at what the ESR specs for that Cap should be it could be determined whether the cap is good or bad,,, Good Stuff... Thank you for posting your videos.. :)

[@terencekaye9948]

Sorry forgot to add,,, so with that circuit using 4 volts, you can test higher voltage electrolytic caps at the rated voltage of the cap and still get an accurate ESR reading? ,, I"m hanging out with the wrong kids,, LOL

[@w2aew]

@@terencekaye9948 There is no need to test at the rated voltage of a capacitor in order to measure the ESR. ESR is not a function of the applied voltage. ESR is only *one* of the several failure modes of electrolytic capacitors, so it can help you find bad capacitors, but it won't find all of them, because some may fail in other ways.

[@pa4tim]

I like that circuit, its elegant. Does it measure ESR or does it measure impedance Z ? Often the Z-type measures only down to somewhere around 10 uF because the reactance part of Z becomes to high. If it only measures the ESR, the real part from Z, it can go down much further. DF becomes lower for small caps but that is because it is a ratio. ESR is going up if frequency drops but not as fast as the reactance. (calculate the ESR of a 100pF cap, it is huge but almost nothing compared to the reactance) ESR is general at the lowest point somewhere between 20 kHz and 100 kHz. ESR in datasheets is stated for 120 Hz in the form of the dissipation factor ( D or DF) , if Z is given, they state that at 100 kHz (for a sinewave ? I do not know how the factories measures, I think some kind of networkanalyser ) www.pa4tim.nl/?p=3775 : More about measuring ESR at several methods Fred, pa4tim

[@w2aew]

It measures Z really. So, only designed for checking ESR of electrolytic caps - common failure in consumer electronics. It uses a measurement frequency of about 100kHz.

[@reproeletronicos1309]

correcting my ammeter is 9.5 micro ampscorrecting my ammeter is 9.5 micro amps

[@GlennPierce]

Hi. I am trying to replicate this circuit. Trouble is when I create a short for the test capacitor I don't get a dc signal as good as you. I get www.dropbox.com/s/bcwdme8ul4mm75y/DS1Z_QuickPrint1.png?dl=0 at Q4 collector. Removing the short I get www.dropbox.com/s/6juovg10bz49hdv/DS1Z_QuickPrint2.png?dl=0 any idea what could cause this. I am using 2n2222 transitors and a 2n2907 but not much else is different. Voltages look more or less correct as on the schematic. Thanks

[@GlennPierce]

Actually I think it may have been stray capacitance or loose connections. Breadboard's drive me nuts.

[@gilberto5018]

Aqui Brasil me ajuda por favor

[@junemahinay12]

WHAT IS THE VALUE OF R24 ?

[@w2aew]

Depends on the full scale deflection of the meter (Ifsd), and the meter resistance (Rmeter) and the trim pot (Rpot). Value isn't too critical because you can make up for it with the pot. Rough approx: R24 = 0.75/Ifsd - Rmeter - Rpot/2

[@junemahinay12]

NO EXACT VALUE SIR ? I WILL FOLLOW THE SCHEMATIC DIAGRAM , I JUST WANT TO BUILD MY OWN ESR METER , THANK YOU VERY MUCH , IT MEANS SIR EVEN NO NEED THE R 24 TO INSTALLS ?

[@w2aew]

Since the value depends on the particular analog meter you are using (full scale current value and meter resistance), I can't give you an exact value.

[@junemahinay12]

SIR YOU HAVE YOU TUBE VIDEO ON HOW TO CALCULATE THE R-24 ? SO I HAVE AN EXAMPLE IN ORDER I ABLE TO GET THE VALUE, THANK YOU AGAIN

[@w2aew]

Impossible to give you a specific value because your meter is unknown to me. My suggestion: Build the circuit and start with R24=2.2K. If you can adjust the pot to full scale deflection on the meter with DUT terminals shorted, then you're done. If you can't reach full scale, then lower resistor value to 1K and try again. If you can reach full scale, but near the end of the pot range, then adjust R24 as needed to give yourself more "headroom" on the pot adjustment.

[@hullinstruments]

Man I wish there was a premade kit or circuit board for this. It seems like it would be extremely useful

[@MrWasim100100]

Nice video. Can I use *_BC547_* instead of *_3904 NPN_* in ESR meter

[@cbhargava]

Yes BC547 should work

[@svsv9]

@@cbhargava Hi Sr. Chetan. Silly question, I have seen this project some build this with ceramic cap others with 2 Electrolytic and 4 ceramic cap. Wondering the correct ones to use?

[@EdEditz]

Just a follow up on my last comment. I spend all day today designing a print then making it, soldering components etc etc and here's the finished product (see link). It worked at first try. :) I use two bits of copper instead of test leads. You can just touch the copper with the legs of the capacitor to get a measurement. www.flickr.com/photos/ededitz/35123697504 One question I have though. From which value onwards would this thing be accurate? Because if I test capacitors below 1 µF they all indicate high. And on the EEVBlog the designer does state that it's more of an impedance meter but at high capacitance that's the same as ESR. How high would that be?

[@siavasharash5448]

I made that lovely circuit and its working fine but i just have a 2000uA multimeter so i shòrted R24 and set the pot. On minimum resistance. But i get just 14uA in out put i gess because of high ohmic internal resistance of my meter in 2000ua Is that possible i change some of resistors to increase the output or not? Check this image pls drive.google.com/file/d/10untKeCUeVkLw2dKt27mfuI06Q1kJm6R/view?usp=drivesdk

[@w2aew]

You could try scaling down R15, 16, 17, 18, 19, and 20. Start by cutting them all in half and see if that gives you more deflection when the test leads are shorted.

[@siavasharash5448]

Thanks. Problem of my circuit was the two 2.2nf capacitors i installed instead of 2.2uf. Anywey i solve that and i get 104 microamp in close test lead condition for a moment But after that the output completly wanished. Is that possible it because of low quality of the fake chinese transistors i have used. After first try i check those by multimeter and no issue found. What do you think???

[@mrnmrn1]

+w2aew Nice video, well explained. You have a new subscriber. I really like the circuit also. I will definitely try it. I'm currently using a slightly modified Ludens ESR meter since 2010, I'm almost completely satisfied with it - I just want to enhance the lower readings, although the difference between e.g. 0.05 ohm and 0.1ohm can be noticed (not read precisely, just a hint of needle moving) with it in its current state. It has a much more non-linear scale than the original - which is good, because the lower region is stretched, so I can distinguish 0.05 ohm from 0.1 ohm, while still able to read 10ohms in the same, single range. ludens.cl/Electron/esr/esr.html I wonder what is the current consumption of this 5 transistor circuit. Maybe I will consider to build a FET oscillator if this tricky BJT one draws too much current. If I remember correctly, my Ludens ESR meter eats less than 1mA from a 9V battery. With a low drop 5V regulator, it can run on an alkaline battery for about a year - with a *lot* of accidental idle running, sometimes a week long :). I will consider to use a transistor array - if I remember correctly, there are some CAxxxx transistor arrays with 4 NPN and one PNP independent transistors in a common 16 pin DIP package. Maybe it worth to try it - better matching, maybe lower temperature drift caused by potentially unequal temperature changes of the standalone transistors.

[@w2aew]

Current draw for this circuit is about 25-30mA if I recall correctly.

[@mrnmrn1]

***** Thank you for the answer. Well, in that case, I still want to try it, but only for curiosity, or maybe for a benchtop meter with mains supply.

[@siavasharash5448]

Is quality of transistors matter? Fake chinese transistors working as well or not?