Author Topic: What about home made (ESR) Meter ? (Read 69328 times)

Kiriakos-GR · « **on:** August 15, 2011, 11:26:25 pm »

I just found one video about a home made (ESR) Meter.

The web page about it is here.
http://ludens.cl/Electron/esr/esr.html

I am trying to understand if the idea about getting fooled from an damaged capacitor,
is still on, when we use the latest and greatest capacitor testers found on the most modern and expensive DMM ?

ejeffrey · « **Reply #1 on:** August 16, 2011, 08:50:56 am »

The most common form of degradation of electrolytic capacitor is by increasing series resistance. A capacitance meter doesn't measure this -- it measure only the reactive/capacitive part of the impedance. It isn't that the capacitance meter is malfunctioning or getting fooled, it just isn't measuring what you need to know. For a full measurement you want an LCR meter that can measure both the capacitance and the ESR/Q/dissipation factor (which are all equivalent) at a selectable frequency. A simple ESR meter is a lot easier to build and is effective at identifying bad devices.

Balaur · « **Reply #2 on:** August 16, 2011, 02:02:14 pm »

Quote from: Kiriakos-GR on August 15, 2011, 11:26:25 pm

The web page about it is here.
http://ludens.cl/Electron/esr/esr.html

I am trying to understand if the idea about getting fooled from an damaged capacitor,
is still on, when we use the latest and greatest capacitor testers found on the most modern and expensive DMM ?

Yassou Kiriakos,

This is exactly the same schematics I've used myself. When I'll get home I'll put a picture eventually.

I've replaced the internal board of a 8 euros analog multimeter with my board while taking care of re-using the selector button for on/off; measured the indications while using a series of low-value resistors and changed the original scale with a custom design (as shown) to be able to read accurately.

Works nicely enough for my needs and it was able to provide a surprisingly useful service.

One drawback of this particular implementation is that the working frequency is a fixed 50KHz, while a more sophisticated approach could be to use several choices up to 100KHz maybe.

Cheers,
Dan

Kiriakos-GR · « **Reply #3 on:** August 16, 2011, 10:00:13 pm »

Hi Balaur

Thanks for the picture about the analogue meter.
Yes the idea about the conversion of one cheap analogue multimeter looks fantastic smart !!

No way to use the body of my own analogue Metrawatt for a such a project, but I will find something in the way.

I would love to see all the details of your project, and mostly to see what version of transformer you had find for it.

Balaur · « **Reply #4 on:** August 16, 2011, 11:19:02 pm »

Hello Kiriakos,

Thank you for your interest.

Here are some details about my implementation.

I have found a Mastech M1015B in my local home improvement store for about 8 euros or so. The donor provided the shell, the microampere meter, the full-scale adjustment potentiometer and the selector knob.

I had tried to wound my own transformer but I didn't had enough of the correct wire gauge at hand. The transformer you see in the picture is retrieved as is from a defective computer switching supply. The turn ratio is a bit different and I had to modify the R8 value to avoid saturation.

The galvanometer is a 150uA or so. I've reused the original ohm adjust pot as a full-scale (0 ohm) pot.

The galvanometer display is made by myself. I've measured the deflection for a few resistor values (this is where your resistor box could have come in handy) and used the Galva software to design a new replacement panel that I've laminated and cut to size.

The PCB is a one-side job (with only two wires). The selector knob is used to power on/off the meter. I had to measure the size, the adjustment and selector positions to ensure the good fit. It worked out nicely in the end.

Power is provided by a 9v battery that fits in the original AA battery after some modding.

Cheers,
Dan

Kiriakos-GR · « **Reply #5 on:** August 17, 2011, 12:26:55 am »

Great work the least that I can say !!

What is the value of the C4 ?
And the C8 ? does not look clearly

w2aew · « **Reply #6 on:** August 17, 2011, 06:10:09 am »

For what it's worth - I also have a video of the ESR meter that I built several years ago. Here's the link. It's not as nice looking as the one at the head of this thread, but it works well...

Balaur · « **Reply #7 on:** August 17, 2011, 08:01:35 am »

Quote from: Kiriakos-GR on August 17, 2011, 12:26:55 am

Great work the least that I can say !!

What is the value of the C4 ?
And the C8 ? does not look clearly

Thanks!

C4 is a 10uF, C8 is a 100nF.

Cheers

ejeffrey · « **Reply #8 on:** August 17, 2011, 08:40:38 am »

Quote from: Balaur on August 16, 2011, 02:02:14 pm

One drawback of this particular implementation is that the working frequency is a fixed 50KHz, while a more sophisticated approach could be to use several choices up to 100KHz maybe.

If you want do that, I think it is better to implement a full LCR meter. A fixed frequency is sufficient to test the vast majority of electrolytic capacitors you will run across. Maybe a simple thing to do would be to put a potentiometer to set the frequency roughly, and you can just see if the ESR varies with frequency. At the low end, the capacitor's capacitance will start to affect the reading, and at the high end maybe the ESL will be a problem but there should be a very broad minimum for properly functioning capacitors.

With a proper LCR meter you can measure separately the ESR and C at any given frequency, so you can properly measure the low frequency behavior as well.

Kiriakos-GR · « **Reply #9 on:** August 17, 2011, 02:26:10 pm »

It looks that many started to use the word " frequency behavior "

and this had born in my head some extra question marks.

Questions :
The correct Frequency ( for testing )has to do with the type of the capacitor ? ( electrolytic tandalium ceramic )
OR
the high frequency ( 150KHz) can tell if the capacitor are totally healthy for usage in high ripple situations like Pulsing PSU ?

And the Chery in the pie

The one who does analogue TV repairs , does it have the same needs about the LCR testing Frequency,
with some one who does exclusively repairs on Pulsing PSU ?

Balaur · « **Reply #10 on:** August 17, 2011, 04:15:49 pm »

Ideally, any ESR readings at a given frequency should be corrected by removing the expected reactance, according to the cap value and the working frequency.

The kind of simple ESR meters that we are discussing rely on the assumption that the reactance of the cap is negligible wrt. the ESR at the current working frequency. To fulfill this expectation, the working frequency and the cap value should be high enough. Or, the operator could correct the value by using pre-computed tables or additional scales.
A more sophisticated approach should consists in measuring the cap value, computing the reactance and deducting the ESR.

As an example, a 10 uF cap @ 100 KHz frequency has a 0.159 Ohms reactance. Good ESR expectations for common aluminium caps are in the range of 0.1-5 Ohms.

Low ESR electrolytic caps (both aluminium and tantalum-based) are available. Ceramics have a very low ESR (<0.01).

The choice of the working frequency is indeed dependent of the required application. Electrolytic caps are usually used with low (<a few hundreds KHz) applications. A practical 100 KHz frequency for a ESR seems reasonable for most cases, including checking capacitors used in switching PSUs and TV repairs.

I would guess that a higher working frequency for measuring the ceramic capacitors could be useful in order to minimize the reactance. However, I haven't really seen very high frequency (i.e. >> 150 KHz) ESR meters.

Kiriakos-GR · « **Reply #11 on:** August 17, 2011, 05:45:17 pm »

Thanks Balaur

I will start working on this new project about making my own home made (ESR) Meter,
in few days from now, my bench space is currently occupied.

Due the fact that I am currently working on a B&O TV set, I had the chance to check about 60 electrolytic capacitors,
I discovered that the small ones like 0.47uF to 10uF, are the most " sensitive group " about indicating a damaged.
The Agilent DMM U1272 did a great work, and even if it rared at 10.000 uF it managed to measure up to 11.200 uF at easy.

One last general question , due the fact that I own one tone generator that it has a square wave output up to 25KHz,
is there any way, to work out with it , in combination with a DMM and get similar readings , like to was an dedicated ESR meter ?

ejeffrey · « **Reply #12 on:** August 17, 2011, 06:18:42 pm »

Just apply your tone generator and measure RMS voltage and current with two meters. Volts/amps = ohms.

alm · « **Reply #13 on:** August 17, 2011, 08:27:33 pm »

Watch the AC current bandwidth of your meter if you do this, it's often less than the AC voltage BW. Especially if you use a square wave, but if you measure current, you might as well use a sine. Putting a resistor in series seems like the obvious solution to me, but I haven't researched ESR meters. There's a fair bit of documentation about DIY ESR meters, some methods are more accurate than others.

ejeffrey · « **Reply #14 on:** August 17, 2011, 09:10:43 pm »

I happen to know that Kiriakos has a meter that will read out to 100 kHz on volts and amps

A series resistor is a good idea in any case. The tone generator is not designed to drive such a low impedance -- the capacitor is essentially a short circuit at this frequency. I don't know how small a series resistor you can get away with, it will depend on your tone generators output impedance. Probably either 600 ohm or 50 ohm. With 600 ohm the voltage drop across your capacitor will only be a few millivolts per ohm of ESR, which may limit your resolution. With a 50 ohm function generator you should have no problem.

alm · « **Reply #15 on:** August 17, 2011, 10:08:13 pm »

Quote from: ejeffrey on August 17, 2011, 09:10:43 pm

I happen to know that Kiriakos has a meter that will read out to 100 kHz on volts and amps

Which meter? Few handhelds have 100kHz ACI bandwidth.

Kiriakos-GR · « **Reply #16 on:** August 17, 2011, 11:51:46 pm »

True I can do 100kHz on ACV, but only 2kHz at ACI .

I bet that my reply helped Alm to not had a hart attack .. LOL

Thanks for all the suggestions.

I will share my results as soon I run few tests.

Conrad Hoffman · « **Reply #17 on:** August 20, 2011, 04:12:50 am »

Just some armchair thoughts on the matter-

ESR meters are used on caps that fail, and that would mostly be electrolytics of a few uF and higher. Thus a fixed frequency of 50 or so kHz seems fine. Almost any cap one would be suspicious about would be essentially a short circuit at that frequency. For the service person an ESR meter makes a lot of sense.

That said I prefer a proper LCR meter, but not the common types built into DVMs and such. What I want is a proper LCR meter that will give me dissipation factor (DF) and Q (1/DF). Dissipation factor tells me how much energy I got back out for what I put in on each cycle.

Further, many commen meters use the series capacitance model, and that can totally mislead you with defective caps if you're not paying attention. A cap with high dissipation can give you an artificially high capacitance reading- the bad cap looks good. If the meter doesn't read dissipation, it's pretty much useless except for sorting parts by value.

When in doubt, the parallel capacitance model makes a lot more sense. You'll see high dissipation combined with a low capacitance reading, which is what you'd expect from a bad cap. There's nothing wrong with the series model or the meter, it's just how the math works.

I've got some useful capacitance utilities and articles on my site at http://www.conradhoffman.com

Kiriakos-GR · « **Reply #18 on:** October 04, 2011, 01:27:14 am »

Ok got my spare parts in hand, and even made a hand made transformer ,
about the transformer I did my best because I had to use used parts.

The ferrite transformers found in PC PSU, its almost impossible to open them up and rewired them.
Mostly because the ferrite are glued, and if you use force the ferrite breaks apart.
Even so I did all my hokes-pokes, and managed to open it up.

My first attempt will be to replicate the primary thread link.
Wish me luck.

eliocor · « **Reply #19 on:** October 04, 2011, 08:11:20 am »

Quote from: Kiriakos-GR on October 04, 2011, 01:27:14 am

[...] The ferrite transformers found in PC PSU, its almost impossible to open them up and rewired them.
Mostly because the ferrite are glued, and if you use force the ferrite breaks apart. [...]

Put your transformer in boiling water for some minutes: the two ferrite parts will separate easily.

firewalker · « **Reply #20 on:** October 04, 2011, 08:45:02 am »

Sometimes I use a solution of paint removal or acetone.

Alexander.

Quote from: eliocor on October 04, 2011, 08:11:20 am

Quote from: Kiriakos-GR on October 04, 2011, 01:27:14 am
[...] The ferrite transformers found in PC PSU, its almost impossible to open them up and rewired them.
Mostly because the ferrite are glued, and if you use force the ferrite breaks apart. [...]

Put your transformer in boiling water for some minutes: the two ferrite parts will separate easily.

Kiriakos-GR · « **Reply #21 on:** October 05, 2011, 12:36:33 pm »

Thanks for the tips, If my current transformer fails, I will need probably another one ...

In one piece.

BravoV · « **Reply #22 on:** October 06, 2011, 03:25:53 am »

I know you got all your components there, just want to share another version that is using 100KHz (this is more common freq) and the best part is "NO INDUCTOR"

, also it has an internal discharge diodes (DS1 and DS2) which I think is good enough for common caps when they're still charged.

Source - > http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/index.htm

Kiriakos-GR · « **Reply #23 on:** October 06, 2011, 04:30:49 am »

Have you built this one ?
Do you have test it ?

amspire · « **Reply #24 on:** October 06, 2011, 05:10:36 am »

Inspired by Kiriakos's post, I decided it was about time I made an ESR tester too.

I had seen the circuit from BravoV, but I decided on the transformer based approach as well. The bridge circuit needs the full 9V from the battery, and it draws a fair bit of current, so you would have to re-zero the meter every time the battery volts falls.

The transformer based circuit is a lot more efficient and stable. With the regulator, it looks like it doesn't need to be zero'ed more then once.

For the transformer, I took a ferrite toroid off a dead PC motherboard, and wound it. It is only about 15mm in diameter with about 420 turns on the primary, 20 on the secondary. Works great. I will run it at 100KHz, but the transformer could do 500KHz or more easily. Maybe I will have switchable frequencies.

I went and ordered a $10 multimeter that looks like it has a decent 50uA meter movement. I will build the ESR meter into it. It has a 9V battery holder. I will probably build the ESR circuit in the space the AA cell currently occupies.

Richard

Kiriakos-GR · « **Reply #25 on:** October 06, 2011, 07:12:06 am »

About the meter for the ESR tester I have run in to problems, the local stores haves 100uA 150 200 300 but no 50uA in stock,
and it costs 7 Euros.
And one cheap analogue multimeter about 8 Euros.

From the other hand , the Italian circuitry shows that the connected multimeter is set to 500mA !!
How can this be right ? when the battery is a single 9V !!

Balaur · « **Reply #26 on:** October 06, 2011, 07:38:08 am »

Quote from: Kiriakos-GR on October 06, 2011, 07:12:06 am

About the meter for the ESR tester I have run in to problems, the local stores haves 100uA 150 200 300 but no 50uA in stock,
and it costs 7 Euros.
And one cheap analogue multimeter about 8 Euros.

You can use any reasonably-sized galvanometer that the opamp can safely drive. Obviously, you will need to adjust the pot + resistance in series with the galvanometer in order to adjust the full-range (0 ohms indication).

There are two main things that are useful with the schematic you selected:

- Verify whether the amplitude of the signal on the output of the transformer is low enough.
The original transformer has a 400:20 ratio. That means that a 5V peak-to-peak signal generated by the first opamp will become a 250mV at max applied on the tested capacitor. This low value is required to not polarize any junctions if you test the cap in circuit. If the transformer you use has a different ratio, you will need to adjust the second opamp gain to not saturate the rectified signal for low ESR values (basically, when test leads are shorted, the output of the second opamp should be as high as possible but no saturation)

- Instead of the single adjustment pot, use resistor and a pot. This way, you will have a much better adjustment window.

Cheers,
Dan

Balaur · « **Reply #27 on:** October 06, 2011, 07:50:41 am »

Quote from: Kiriakos-GR on October 06, 2011, 07:12:06 am

From the other hand , the Italian circuitry shows that the connected multimeter is set to 500mA !!
How can this be right ? when the battery is a single 9V !!

Are you looking at the picture of the multimeter?

The original galvanometer is supposed to be 500 microamps. The gentlemen on the indicated link (http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/index.htm says that he used a 1mA galva with a transistor amplifier. Why? You just need to adjust the series resistors.

Kiriakos-GR · « **Reply #28 on:** October 06, 2011, 02:32:36 pm »

You are totally correct Balaur ...

In this case if I start the Italian idea I will need a 500uA meter, and no extra amplification stage.

Thanks for the info..

The good part is that I have not start anything yet,
I would prefer to make a full scale ESR tester, and not to convert a multimeter.
The IC1=TL084 needs more voltage, like steady 9-10V .
And so it can not be powered by batteries if you seek 100% success.
But the first design it can be powered with 9V or less.

Any way, there is still some time for suggestions .

BravoV · « **Reply #29 on:** October 07, 2011, 04:54:20 am »

No Kiriakos, I haven't build it yet, its just your thread here has inspired me to build a non mcu based esr meter, and this Italian design is in my bookmark, thought I'd share it here, also I might join you here building discrete esr meter, its just its not easy to get the enameled copper wires for the inductor here, for the core, we got plenty, for diy winding, I just want a new and fresh copper wire rather than used/ salvaged wire, it might have chipped/scratched enamel.

Already built one using mcu based few years ago and working fine, but it was hijacked and kidnapped by one my good friend here

, so I think its time to build another one but non mcu based.

Quote from: Kiriakos-GR on October 06, 2011, 02:32:36 pm

Any way, there is still some time for suggestions .

Another discrete non mcu based variant design as an option -> http://www.siliconchip.com.au/cms/A_103805/article.html

kripton2035 · « **Reply #30 on:** October 07, 2011, 07:02:40 am »

hello to you all,
to give you some ideas, please consult my esr repository page
you will get lots of schematics, and i hope you will get inspiration for your own esr meter !!!

http://kripton2035.free.fr/esr-repository.html

I'm currently designing a digital esr meter with a minimum component count
(6 including the two protection diodes...) I will post on the site as soon as it works !

regards,

BravoV · « **Reply #31 on:** October 10, 2011, 06:03:11 am »

Quote from: kripton2035 on October 07, 2011, 07:02:40 am

hello to you all,
to give you some ideas, please consult my esr repository page
you will get lots of schematics, and i hope you will get inspiration for your own esr meter !!!

http://kripton2035.free.fr/esr-repository.html

I'm currently designing a digital esr meter with a minimum component count
(6 including the two protection diodes...) I will post on the site as soon as it works !

regards,

Hey Kripton, its amazing you've collected so many esr measuerement circuits, thanks.

PS : I noticed at one of the German's circuit, you're using google translation, now you can use better one here -> https://www.eevblog.com/forum/index.php?topic=5087.0 and post it at your web site.

amspire · « **Reply #32 on:** October 10, 2011, 06:22:25 am »

Quote from: kripton2035 on October 07, 2011, 07:02:40 am

I'm currently designing a digital esr meter with a minimum component count
(6 including the two protection diodes...) I will post on the site as soon as it works !

regards,

I am looking forward to see this.

I guess it has to have a micro and display, a supply capacitor, the two diodes.

And that leaves one more component - I guess it would have to be a resistor.

I suppose you could get the two diodes in one package and call it one component.

Whatever your plan is, if you can pull it off, it could be very popular.

Richard

kripton2035 · « **Reply #33 on:** October 10, 2011, 09:35:42 am »

Quote from: BravoV on October 10, 2011, 06:03:11 am

Hey Kripton, its amazing you've collected so many esr measuerement circuits, thanks.

PS : I noticed at one of the German's circuit, you're using google translation, now you can use better one here -> https://www.eevblog.com/forum/index.php?topic=5087.0 and post it at your web site.

uh yes Richard's translation is far better than google translate !!!!
I will correct my documents and post them soon. thanks for it !

kripton2035 · « **Reply #34 on:** October 10, 2011, 09:43:02 am »

Quote from: amspire on October 10, 2011, 06:22:25 am

And that leaves one more component - I guess it would have to be a resistor.

good guess !

Quote from: amspire on October 10, 2011, 06:22:25 am

I suppose you could get the two diodes in one package and call it one component.

no I didnt but this is a VERY nice suggestion !

saturation · « **Reply #35 on:** October 10, 2011, 11:07:46 pm »

FWIW if you have a capacitance meter that show DF , then ESR can be calculated:

DF is really all you need since ESR proportionate to DF.

So ESR = DF x Xc

For more calculations and samples:

http://www.illinoiscapacitor.com/pdf/Papers/impendance_dissipation_factor_ESR.pdf

amspire · « **Reply #36 on:** October 11, 2011, 02:26:57 am »

Capacitance meters are not great at measuring ESR.

Capacitance meters usually want to measure big valued capacitors at low frequencies, because they are concerned at accurately measuring the capacitance.

The ESR reading is usually done at 100KHz and at that frequency, it is just about impossible to measure the capacitance of an big electrolytic, but it is really easy to measure ESR.

Also ESR meters test capacitors in-circuit, whereas capacitance meters need the capacitor removed from the circuit first.

So if you want to measure ESR, nothing beats a good ESR meter.

Richard.

Conrad Hoffman · « **Reply #37 on:** October 11, 2011, 04:39:42 am »

As owner and collector of many capacitance bridges, I have to agree with Richard. Almost all normal bridges and meters are incapable of measuring big caps at high frequencies. If you want esr, an esr meter is quite handy. I will say however, that I've never seen a bad capacitor that didn't reveal itself, usually in-circuit, with a conventional low frequency dissipation factor measurement. If DF is high and/or Cp is low, it's toast. The only time you can't get good results with an in-circuit measurement is if the cap is already shunted by some low impedance.

kripton2035 · « **Reply #38 on:** October 11, 2011, 06:44:50 am »

hi,
to follow the nice idea from Richard of putting the two diodes in the same package,
does anyone ahave a reference of a double reverse schottky diode in a single package ?
like the bat54s (the s is important must be reverse diodes) but with higher voltage rating like 500v or 1000v ?
thanks.

amspire · « **Reply #39 on:** October 11, 2011, 07:03:33 am »

Quote from: kripton2035 on October 11, 2011, 06:44:50 am

hi,
to follow the nice idea from Richard of putting the two diodes in the same package,
does anyone ahave a reference of a double reverse schottky diode in a single package ?
like the bat54s (the s is important must be reverse diodes) but with higher voltage rating like 500v or 1000v ?
thanks.

Schottky diodes cannot be high voltage - the physics doesn't allow it.

But aren't you putting them back to back, so the maximum voltage across the diodes is one diode drop?

Richard

kripton2035 · « **Reply #40 on:** October 11, 2011, 12:02:06 pm »

yes I put them back to back like in the bat54S (and not bat54a or c they are the same direction)
ok for "normal" diode. I only found same direction diodes in a single package ...

amspire · « **Reply #41 on:** October 11, 2011, 12:20:52 pm »

So you don't need a high voltage rating. The diodes never have more then one forward diode drop voltage across them, so you can use any Schottky you can find.

Richard

amspire · « **Reply #42 on:** October 11, 2011, 12:54:21 pm »

I am assuming you are testing below the Schottky forward voltage.

Here is my suggestion from Digikey:

http://search.digikey.com/us/en/products/CDBHD240-G/641-1213-1-ND/1678631?vendor=641

The diodes are 2A each, and the bridge has 4 diodes so that will make 4A current capacity in each direction. The 8.3 mSec surge current is 100A for each pair.

The forward voltage of these will be under 200mV, but if you need more voltage, the CDBHD260-G has double the forward voltage of the 240.

amspire · « **Reply #43 on:** October 11, 2011, 11:47:12 pm »

I hadn't thought of that. Nice!

For the ESR meter, you need to measure sub ohm resistances, and it looks like the circuit in the app note has way too much series resistance. If the series resistance is reduced to 1 ohm, then it will limit the current at 1A. A bit much.

But I will definitely keep it in mind for protecting high impedance inputs. It has to compete of course with the PTC now in every multimeter.

Richard

amspire · « **Reply #44 on:** October 12, 2011, 05:06:38 am »

The force and the sense connections can be seperate but the biggest problem here is how to add some sort of protection without going above 6 5 components for the total design.

That seems to be the design mission.

Richard.

kripton2035 · « **Reply #45 on:** October 12, 2011, 09:57:46 am »

AcHmed99,
yes it is to protect the input of the esr meter
but as richard already said, it is for measuring around the ohm value
so it's not a good thing to insert a 1kohm resistor in the measure ...
anyway thanks for the trick.

I'm looking for a two diodes in one package component
but all I see are for rectifiers of smps, so they have the cathode of the diode connected together
I want the two diodes reversed.
richard say it doesnt exist in schottky, so does it exist in normal diode with voltage like 500V ?
I repeat this is to protect the measuring circuit from charged capacitors of smps ...
thanks

amspire · « **Reply #46 on:** October 12, 2011, 10:16:18 am »

I have no idea how you are going to protect the meter with two reversed diodes.

You have got me stumped there.

They cant be in series with the test capacitor, and if they are in parallel with the capacitor, they will do nothing as no electro will ever have more then 450VDC.

What is left?

Richard

kripton2035 · « **Reply #47 on:** October 12, 2011, 11:15:13 am »

some protection like this one :

amspire · « **Reply #48 on:** October 12, 2011, 11:28:22 am »

The maximum forward drop possible across the diodes in that circuit is one diode drop, so any diode rated at more the 1V will be fine.

One diode is always forward biased, and the trick is to keep the measurement voltage below the turn-on voltages of the diodes.

The only reason someone used the 700V 1N4007 diodes was because it is a very common, very cheap part.

So you can use your BAT54S diodes or for more rugged diodes, you could use my bridge rectifier package.

Richard.

kripton2035 · « **Reply #49 on:** October 12, 2011, 01:01:38 pm »

I also have an UC3611 bridge that is rated 3A
will certainly do with it...
regards,

Conrad Hoffman · « **Reply #50 on:** October 12, 2011, 02:14:40 pm »

Maybe use a couple LEDs for more headroom? Not sure how fast they are.

eternal_noob · « **Reply #51 on:** October 13, 2011, 04:25:57 pm »

Here is the meter i built awhile back. Maybe early 2010 if I remember correctly. I have not to this date used the meter for checking capacitors that much, but it became very handy when locating and confirming bad relay contacts in a control unit for an old central heating furnace. The combination of an analog meter movement and a tiny AC current makes it usable for detecting even pretty small flaws in switches or contacts in general.
The transformer core is scavenged from a dead CFL bulb so there is a little tip for you that want to DIY a simple ESR meter.

Kiriakos-GR · « **Reply #52 on:** October 13, 2011, 07:55:36 pm »

Did you use 400/20 windings ratio on this transformer ?

eternal_noob · « **Reply #53 on:** October 13, 2011, 08:14:47 pm »

Quote from: Kiriakos-GR on October 13, 2011, 07:55:36 pm

Did you use 400/20 windings ratio on this transformer ?

If that question was for me, yes I did. I didn't really need to rewind it. Originally the former/core was filled to the brim with approx 0.15mm wire and it actually was exactly 400 turns. So, if you come across one of those, you just have to add some turns for a secondary.
Here is the output waveform of the transformer:

FenderBender · « **Reply #54 on:** November 02, 2011, 02:51:39 am »

Quote from: w2aew on August 17, 2011, 06:10:09 am

For what it's worth - I also have a video of the ESR meter that I built several years ago. Here's the link. It's not as nice looking as the one at the head of this thread, but it works well...

Do you have a high(er) res shot of the schematic. I can see it for the most part, but I'm not sure about a few of the parts. ie. What transistor did you use?

I'd like to build yours. It seems well done.

Kiriakos-GR · « **Reply #55 on:** November 02, 2011, 03:27:07 am »

Well I have one wild idea and I need to ask if there is any hope for it.

I have next to me the analogue Metrawatt multimeter with an minimum mA range of 2,5 mA .

And I am thinking if there was an sort of amplifier circuitry so to operate my analogue multimeter instead of an separate 50 uA panel meter,
it would be a great idea.

But is it possible?

I know that I sound as wacko , voltage amplifier = normal / signal amplifier = normal / current amplifier = crazy !!

amspire · « **Reply #56 on:** November 02, 2011, 04:03:41 am »

Quote from: Kiriakos-GR on November 02, 2011, 03:27:07 am

And I am thinking if there was an sort of amplifier circuitry so to operate my analogue multimeter instead of an separate 50 uA panel meter,
it would be a great idea.

But is it possible?

Definitely you could use your meter for almost any of the popular non-digital ESR circuits . Especially since the 75mV range is also a 750uA range, It would be very easy to modify most of the circuits for a different meter current. In most cases, it is probably a matter of changing the series resistor to the meter and the value of the zero ohms potentiometer.

Richard.

Kiriakos-GR · « **Reply #57 on:** November 02, 2011, 04:31:09 am »

Richard you just made my day.

750uA on the mV , I just realized it too because of you.

And here is my 50uA on the screen, a quick test with my precision current source.

.

w2aew · « **Reply #58 on:** November 04, 2011, 11:44:10 pm »

Quote from: FenderBender on November 02, 2011, 02:51:39 am

Quote from: w2aew on August 17, 2011, 06:10:09 am
For what it's worth - I also have a video of the ESR meter that I built several years ago. Here's the link. It's not as nice looking as the one at the head of this thread, but it works well...

Do you have a high(er) res shot of the schematic. I can see it for the most part, but I'm not sure about a few of the parts. ie. What transistor did you use?

I'd like to build yours. It seems well done.

The NPN is really pretty non-critical - I used a 2N2222A. Here's a better pic of the schematic... I never did an electronic copy of it, so hopefully this vidcap is OK. If not, let me know and I'll scan the hand-drawn schematic...

FenderBender · « **Reply #59 on:** November 05, 2011, 02:42:39 am »

Oh alright. Just making sure it wasn't anything special, since I didn't give the circuit too much of a look.

I guess I'll just use a 2n3904, I know it has a smaller switching current, but hopefully that's alright. I have like 100 of them...

Thanks. I can see the schematic, though other might appreciate it. Thanks for the contribution.

FenderBender · « **Reply #60 on:** November 08, 2011, 11:53:34 pm »

One question regarding the schematic.

The arrows indicate a connection to ground...but what to the circles mean?

Thanks.

amspire · « **Reply #61 on:** November 09, 2011, 12:38:59 am »

In this case, the circles are the 5V from the 7805 regulator.

FenderBender · « **Reply #62 on:** November 09, 2011, 01:49:09 am »

Quote from: amspire on November 09, 2011, 12:38:59 am

In this case, the circles are the 5V from the 7805 regulator.

Thanks. I assumed as much...You don't by chance have the hard copy around and maybe a scanner...do you?

Well thanks anyway.

amspire · « **Reply #63 on:** November 09, 2011, 03:11:41 am »

Quote from: FenderBender on November 09, 2011, 01:49:09 am

Quote from: amspire on November 09, 2011, 12:38:59 am
In this case, the circles are the 5V from the 7805 regulator.

Thanks. I assumed as much...You don't by chance have the hard copy around and maybe a scanner...do you?

Not sure what you mean. Do you mean the original circuit that "w2aew" used?

It looks familiar. I think it is one of the ones on "kripton2035"'s ESR web page

https://www.eevblog.com/forum/index.php?topic=4476.msg66485#msg66485

Richard

FenderBender · « **Reply #64 on:** November 09, 2011, 04:41:44 am »

I meant do you want to scan the schematic by chance?

amspire · « **Reply #65 on:** November 09, 2011, 05:30:45 am »

Quote from: FenderBender on November 09, 2011, 04:41:44 am

I meant do you want to scan the schematic by chance?

Sorry, still a bit dense. Why would I want to scan the schematic?

I don't have it, but I can get the original any time from the internet. The hand copy that w2aew posted is good enough anyway.

Richard

kripton2035 · « **Reply #66 on:** November 09, 2011, 01:00:18 pm »

Quote from: amspire on November 09, 2011, 03:11:41 am

Quote from: FenderBender on November 09, 2011, 01:49:09 am
Quote from: amspire on November 09, 2011, 12:38:59 am
In this case, the circles are the 5V from the 7805 regulator.

Thanks. I assumed as much...You don't by chance have the hard copy around and maybe a scanner...do you?

Not sure what you mean. Do you mean the original circuit that "w2aew" used?

It looks familiar. I think it is one of the ones on "kripton2035"'s ESR web page

https://www.eevblog.com/forum/index.php?topic=4476.msg66485#msg66485

Richard

funny ... I posted this circuit AFTER w2aew posted it here on eevblog...
none of the schematics I post are mine... I'm only a repository...
sure I will post my 6 components digital esr meter once it works the way I want
but for now none of my schematic are on my web site !

amspire · « **Reply #67 on:** November 09, 2011, 01:32:21 pm »

kripton2035,

My apologies. I had seen this design or something very similar somewhere before W2aew's posting, and thought wrongly is came from you site.

I cannot workout where I saw it now. I did look and this was the closest i could find:

http://members.shaw.ca/swstuff/esrschematic.png

W2aew's does USE an AD8032 IC to rectify and buffer the signal to the meter , which does allow a much less sensitive meter to be used, and probably gives better readings for low ESR readings.

Richard

kripton2035 · « **Reply #68 on:** November 09, 2011, 02:25:21 pm »

I didnt notice any other esr schematic this way neither
and trust me I've seen a lot of esr schematics...

seems that w2aew made an original esr meter...
thats mainly why I added his schematic on my repository !

Kiriakos-GR · « **Reply #69 on:** November 09, 2011, 03:57:22 pm »

Is it possible any prediction about the max uA that the w2aew schematic can have as output for the uA meter?
Lets suppose that there is no zero out pot in this circuitry , what is the max possible uA output ?

saturation · « **Reply #70 on:** November 09, 2011, 08:19:35 pm »

There's a similar discussion here, that could be what you need:

https://www.eevblog.com/forum/index.php?topic=5507.msg71814#msg71814

amspire · « **Reply #71 on:** November 09, 2011, 10:16:41 pm »

Quote from: Kiriakos-GR on November 09, 2011, 03:57:22 pm

Is it possible any prediction about the max uA that the w2aew schematic can have as output for the uA meter?
Lets suppose that there is no zero out pot in this circuitry , what is the max possible uA output ?

If you changes the series resistors to the meter, you could use anything up to a 10mA meter movement.

Kiriakos-GR · « **Reply #72 on:** November 09, 2011, 10:55:00 pm »

Quote from: amspire on November 09, 2011, 10:16:41 pm

Quote from: Kiriakos-GR on November 09, 2011, 03:57:22 pm
Is it possible any prediction about the max uA that the w2aew schematic can have as output for the uA meter?
Lets suppose that there is no zero out pot in this circuitry , what is the max possible uA output ?

If you changes the series resistors to the meter, you could use anything up to a 10mA meter movement.

Thanks, my plan is to make one add-on mini box (ESR circuitry) that will clamp-on with bananas, at the top of my analogue multimeter.
I will post a drawing of my prototype idea later on.

amspire · « **Reply #73 on:** November 09, 2011, 11:22:47 pm »

Quote from: Kiriakos-GR on November 09, 2011, 10:55:00 pm

Quote from: amspire on November 09, 2011, 10:16:41 pm
Quote from: Kiriakos-GR on November 09, 2011, 03:57:22 pm
Is it possible any prediction about the max uA that the w2aew schematic can have as output for the uA meter?
Lets suppose that there is no zero out pot in this circuitry , what is the max possible uA output ?

If you changes the series resistors to the meter, you could use anything up to a 10mA meter movement.

Thanks, my plan is to make one add-on mini box (ESR circuitry) that will clamp-on with bananas, at the top of my analogue multimeter.
I will post a drawing of my prototype idea later on.

If you are going to add it to a multimeter, use the multimeter in voltage mode, not current mode, and eliminate the whole second opamp - it is not needed at all. So you could source a single low voltage high speed opamp to replace the AD8032. All the meter + resistor was doing anyway was reading the output voltage from the output opamp.

The reason why you don't want to use the current ranges of a multimeter is the huge variations in burden voltages between meters. Volts are just volts - it will work an all multimeters.

But this is not really the right circuit to use with a multimeter anyway. You can draw any scale you like on an analog meter, and so for an ESR meter, is ot 0 ohm at full scale, 10 ohms at half scale and 20, 30, and 40 ohms crammed down near the bottom scale. On a DMM you will get nonsense numbers out. You want one of the ESR circuits that gives an output voltage that is proportional to the capacitance ESR. So if the capacitor has an ESR of 0.15 ohms, the meter reads 0.15 volts, or 15.0 mVolts for a more useful scaling.

Richard.

Kiriakos-GR · « **Reply #74 on:** November 10, 2011, 12:36:52 am »

My plan was to use your advice, about the 75mV range that is equal to 750uA.
And make the circuitry as is.

Now I need to look up for the 74CH14N , I do not think that is easy to find in my local retailers.

w2aew · « **Reply #75 on:** November 10, 2011, 03:53:05 am »

Quote from: kripton2035 on November 09, 2011, 02:25:21 pm

I didnt notice any other esr schematic this way neither
and trust me I've seen a lot of esr schematics...
seems that w2aew made an original esr meter...
thats mainly why I added his schematic on my repository !

The design I put together is a combination of ideas I gathered years ago when I built it. The oscillator and DUT circuit were from some of the designs I saw, and the bipolar transistor buffer idea from another. I followed it up with the AD8032 based peak-to-peak detector (DC Restore + Peak Det).

Rufus · « **Reply #76 on:** November 10, 2011, 04:23:02 am »

Quote from: kripton2035 on November 09, 2011, 02:25:21 pm

I didnt notice any other esr schematic this way neither

Maybe because it isn't an ESR meter. It is an impedance meter. At the testing frequency for biggish caps, especially bad ones, most of the impedance is ESR so it serves.

kripton2035 · « **Reply #77 on:** November 10, 2011, 01:11:00 pm »

Quote from: Rufus on November 10, 2011, 04:23:02 am

Quote from: kripton2035 on November 09, 2011, 02:25:21 pm
I didnt notice any other esr schematic this way neither

Maybe because it isn't an ESR meter. It is an impedance meter. At the testing frequency for biggish caps, especially bad ones, most of the impedance is ESR so it serves.

all esr meters are impedance meters aren't they ?
how do you make the difference between an impedance meter and an esr meter
apart the fact that esr meters are impedance meters testing at 100KHz ?

FenderBender · « **Reply #78 on:** November 10, 2011, 06:30:08 pm »

Quote from: amspire on November 09, 2011, 05:30:45 am

Quote from: FenderBender on November 09, 2011, 04:41:44 am
I meant do you want to scan the schematic by chance?

Sorry, still a bit dense. Why would I want to scan the schematic?

I don't have it, but I can get the original any time from the internet. The hand copy that w2aew posted is good enough anyway.

Richard

Oooo my bad. I mixed you up with w2aew somehow...=P

jimmc · « **Reply #79 on:** November 10, 2011, 07:59:49 pm »

Quote from: kripton2035 on November 10, 2011, 01:11:00 pm

...
all esr meters are impedance meters aren't they ?
how do you make the difference between an impedance meter and an esr meter
apart the fact that esr meters are impedance meters testing at 100KHz ?

Using a synchronous (phase sensitive) detector allows the reactive and resistive components to be resolved.
For instance this example from your excellent site http://kripton2035.free.fr/analog%20esr/esr-lowohm-silic.html
Here the switches IC3a & b are driven in phase with the test current form IC3c & d, this will reject the quadrature component caused by the reactance of the capacitor under test.

Jim

kripton2035 · « **Reply #80 on:** November 10, 2011, 08:45:47 pm »

Quote from: jimmc on November 10, 2011, 07:59:49 pm

Quote from: kripton2035 on November 10, 2011, 01:11:00 pm
...
all esr meters are impedance meters aren't they ?
how do you make the difference between an impedance meter and an esr meter
apart the fact that esr meters are impedance meters testing at 100KHz ?

Using a synchronous (phase sensitive) detector allows the reactive and resistive components to be resolved.
For instance this example from your excellent site http://kripton2035.free.fr/analog%20esr/esr-lowohm-silic.html
Here the switches IC3a & b are driven in phase with the test current form IC3c & d, this will reject the quadrature component caused by the reactance of the capacitor under test.

Jim

elektor esr meter uses the same switches system
but I note that they both inject +-5v to the capacitor under test
this imply that you cannot use these kind of esr meters in circuit ?

is it possible to use the same system but with +-100mV test signal ?

there are also on my site the russian go esr meter, which uses a constant current method to measure esr
does this method measure only esr and get rid of the reactance or not ?

amspire · « **Reply #81 on:** November 10, 2011, 09:45:20 pm »

Quote from: jimmc on November 10, 2011, 07:59:49 pm

Quote from: kripton2035 on November 10, 2011, 01:11:00 pm
...
all esr meters are impedance meters aren't they ?
how do you make the difference between an impedance meter and an esr meter
apart the fact that esr meters are impedance meters testing at 100KHz ?

Using a synchronous (phase sensitive) detector allows the reactive and resistive components to be resolved.
For instance this example from your excellent site http://kripton2035.free.fr/analog%20esr/esr-lowohm-silic.html
Here the switches IC3a & b are driven in phase with the test current form IC3c & d, this will reject the quadrature component caused by the reactance of the capacitor under test.

Jim

The quadrature detector only works well if your test signal is a low distortion sine wave. If you look at the schematic circuit of a handheld LCR meter, there is usually something in the order of an 8th order bandpass filter after the signal generator to wipe out all the harmonics. The final signal applied to the device under test has a distortion of something like 0.01% or less. Really accurate bridges go a step further - they also use a bandpass filter after the device under test, partly so they can cope with distortion caused by the device being tested.

If your test signal is a square wave, the harmonics will make the quadrature detector fairly inaccurate in terms of measuring capacitance.

Also, ESR is most easily measured at high frequencies like 100KHz. Capacitance of large electro's needs to be measured at low frequencies like 120Hz. To get a useful esr reading at the same frequency that you can measure the capacitance value, you would have to start designing to a true LCR meter quality. Otherwise, you will have to have two test frequencies to measure the C and ESR.

Nice idea, but is it too much work for results that may often be deceptively wrong? How much time are you going to waste chasing up capacitor problems that are the result of a dodgy meter?

The significance of an ESR test is that with electrolytics, ESR rise is usually the first sign of something going wrong in the capacitor - ESR will rise before capacitance starts to fall. ESR will go up if the electrolyte starts to evaporate, so it is a sign of a capacitor that no longer as a true gas-tight seal. So a basic ESR meter that purely measures the voltage across a capacitor when fed with 100KHz on its own does a pretty good job. Quadrature switching? Don't know why you would even bother.

Richard.

jimmc · « **Reply #82 on:** November 10, 2011, 09:49:09 pm »

In the circuit on your website the open circuit voltage is limited by D1 & 2 to approximately+0.7v and the short circuit current to around + 2 mA (5v/(1.8k +470 +68).
With, say, a capacitor with an ESR of 10 Ohm connected the test voltage will be + 2 mA x 10 Ohm = 40 mV pk-pk; so yes, it can be used for in circuit testing.

To answer your second question no, the only way to separate resistance from reactance is to use a synchronous detector.
(An alternative method would be to use a series inductor to resonate out the capacitive reactance, but this is not practical.)

jimmc · « **Reply #83 on:** November 10, 2011, 10:16:08 pm »

Quote from: amspire on November 10, 2011, 09:45:20 pm

Quote from: jimmc on November 10, 2011, 07:59:49 pm
Quote from: kripton2035 on November 10, 2011, 01:11:00 pm
...
all esr meters are impedance meters aren't they ?
how do you make the difference between an impedance meter and an esr meter
apart the fact that esr meters are impedance meters testing at 100KHz ?

Using a synchronous (phase sensitive) detector allows the reactive and resistive components to be resolved.
For instance this example from your excellent site http://kripton2035.free.fr/analog%20esr/esr-lowohm-silic.html
Here the switches IC3a & b are driven in phase with the test current form IC3c & d, this will reject the quadrature component caused by the reactance of the capacitor under test.

Jim

The quadrature detector only works well if your test signal is a low distortion sine wave. If you look at the schematic circuit of a handheld LCR meter, there is usually something in the order of an 8th order bandpass filter after the signal generator to wipe out all the harmonics. The final signal applied to the device under test has a distortion of something like 0.01% or less. Really accurate bridges go a step further - they also use a bandpass filter after the device under test, partly so they can cope with distortion caused by the device being tested.

If your test signal is a square wave, the harmonics will make the quadrature detector fairly inaccurate in terms of measuring capacitance.

Also, ESR is most easily measured at high frequencies like 100KHz. Capacitance of large electro's needs to be measured at low frequencies like 120Hz. To get a useful esr reading at the same frequency that you can measure the capacitance value, you would have to start designing to a true LCR meter quality. Otherwise, you will have to have two test frequencies to measure the C and ESR.

Nice idea, but is it too much work for results that may often be deceptively wrong? How much time are you going to waste chasing up capacitor problems that are the result of a dodgy meter?

The significance of an ESR test is that with electrolytics, ESR rise is usually the first sign of something going wrong in the capacitor - ESR will rise before capacitance starts to fall. ESR will go up if the electrolyte starts to evaporate, so it is a sign of a capacitor that no longer as a true gas-tight seal. So a basic ESR meter on its own does a pretty good job.

Richard.

We are talking at cross purposes here, I agree with all you've said.

I'm sorry I did not make it clear that I was talking of measuring only the resistive component and rejecting the reactive part.
For this the presence of odd harmonics would not be a problem and so a square wave is OK.

As I've said before ESR meters are not precision component analysers but a very useful diagnostic tool.
They do not measure capacitance.

I would say that a measurement accuracy of +10% is more than adequate for all practical purposes.

Jim

amspire · « **Reply #84 on:** November 10, 2011, 10:35:58 pm »

The point I was making is that if you are measuring at 100KHz, the reactive part is negligible. If you are testing a 1000uF capacitor, you are looking for an ESR better then 50 to 100mohms and the reactive part is 1.6 mOhms. For a 50mOhm ESR in a 1000uF cap, difference between a quadrature detector reading and a plain rectifier will be less then 0.05%.

For capacitors with better then 50mOhm ESR, you are really pushing it to get any accurate reading with two wire measurement.

So all a quadrature/Switching detector is achieving is a technically cool way to rectify AC. Any other sort of rectifier will work as well, but I have no problem with the quadrature detector as a rectifier.

Richard.

kripton2035 · « **Reply #85 on:** November 11, 2011, 08:57:39 am »

ok with all you say
but if you measure always at 100KHz, when you measure the mains capacitor in a smps, its often this one that is bad
and it is only excited with 100 to 120 Hz signal, he never gets 100KHz of its all life except when I test it with the esr meter...
so
also when you see comparison tables of suggested esr values regarding capacitor value
it should be nice to get the capacity together with the esr and indicate directly if these two values are recommended
or not

what do you think of this ?

jimmc · « **Reply #86 on:** November 11, 2011, 11:52:36 am »

Quote from: amspire on November 10, 2011, 10:35:58 pm

The point I was making is that if you are measuring at 100KHz, the reactive part is negligible. If you are testing a 1000uF capacitor, you are looking for an ESR better then 50 to 100mohms and the reactive part is 1.6 mOhms. For a 50mOhm ESR in a 1000uF cap, difference between a quadrature detector reading and a plain rectifier will be less then 0.05%.

For capacitors with better then 50mOhm ESR, you are really pushing it to get any accurate reading with two wire measurement.

So all a quadrature/Switching detector is achieving is a technically cool way to rectify AC. Any other sort of rectifier will work as well, but I have no problem with the quadrature detector as a rectifier.

Richard.

Once again I am in total agreement.
My original post about synchronous detectors was in reply to the question in a previous post...

all esr meters are impedance meters aren't they ?
how do you make the difference between an impedance meter and an esr meter
apart the fact that esr meters are impedance meters testing at 100KHz ?

Jim

alm · « **Reply #87 on:** November 11, 2011, 08:36:05 pm »

Quote from: kripton2035 on November 11, 2011, 08:57:39 am

ok with all you say
but if you measure always at 100KHz, when you measure the mains capacitor in a smps, its often this one that is bad
and it is only excited with 100 to 120 Hz signal, he never gets 100KHz of its all life except when I test it with the esr meter...
so

Because in normal circuits you want the resistance to be small compared to the reactance (capacitance). In ESR meters, you want the ESR to be large compared to the capacitance, especially if you don't use phase information to distinguish resistance from reactance.

Quote from: kripton2035 on November 11, 2011, 08:57:39 am

also when you see comparison tables of suggested esr values regarding capacitor value
it should be nice to get the capacity together with the esr and indicate directly if these two values are recommended
or not

what do you think of this ?

It would be nice, but capacitance is hard to accurately measure in-circuit, which would limit the value of this.

kripton2035 · « **Reply #88 on:** November 13, 2011, 09:45:14 am »

another question, as you seems very qualified on the subject !

can we consider the esr for a given capacitor is (almost?) the same value at 10KHz and at 100KHz ?
I speak about the esr only, excluding the reactance
thanks.

alm · « **Reply #89 on:** November 13, 2011, 03:05:52 pm »

Resistance is not a function of frequency, so the ideal ESR meter would give identical results regardless of frequency, since it would measure ESR independent of capacitance and ESL. Of course this falls apart if the capacitor does not match the C-R-L model.

jimmc · « **Reply #90 on:** November 13, 2011, 04:44:18 pm »

The 'perfect' capacitor in series with a 'perfect' resistor is only a model, of a real world capacitor.
At high frequencies where the reactance is low (compared with the ESR) it is works pretty well, however as the reactance rises other losses start to become significant leading to an apparent rise in ESR.

For an example see http://www.niccomp.com/help/techinfo/NRE-HL102M16V-ESR-Temp-Freq0909.pdf
(Remember that the reactance of 1000uF at 1kHz is 0.16 ohm.)

Jim

kripton2035 · « **Reply #91 on:** November 13, 2011, 05:03:01 pm »

effectively on the graphic, the esr changes 3 times below 10KHz
but it stays quite the same from 10KHz to 1MHz
thanks for this !

FenderBender · « **Reply #92 on:** June 23, 2012, 06:57:31 pm »

Hey guys. Old thread...I know. I asked one of our users, w2aew, if he'd scan me the schematic of his ESR meter which you can find here on youtube:

I couldn't 100% see the schematic, so here it is.

kripton2035 · « **Reply #93 on:** June 25, 2012, 09:57:18 pm »

nice idea - I 'll update my esr repository with that schematic. - thanks.

ramin110 · « **Reply #94 on:** October 04, 2018, 08:26:12 am »

Hi guys,
I want to build my own ESR meter based on Alan Design but in his design, he used ad8032 IC and I can't find it in my country so I find the ad8572 one and as soon as I plug it to the power supply it fried in an ms so I want to find a common replacement IC for this IC.
Can You help me? Thanks
my design link:
https://www.eevblog.com/forum/beginners/esr-meter-105123/


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