ESR Meter Adapter Design and Construction

[Jay_Diddy_B]

Anyone have a spare or populated PCB made up?

I have sent you a PM.

Regards,

Jay_Diddy_B

[3roomlab]

i wanted to see if i understood the concept of the meter, and so i tried it with a 4017 as a drive for the 4066. however i am not sure if it is a simulation problem, it seem to work in a weird way.

generally what i did is 1Mhz --> 4017 --> select pins to use to trigger/sense
using 6 of the output to split 1 cycle (of 100kHz) into 3 parts of +ve/-ve trigger (cyan waveform), and then 2 of the 3 parts as a "sense" trigger (magenta/blue waveform). did i do this in the correct way? (ignore the incomplete opamp at the sense end)

[Jay_Diddy_B]

i wanted to see if i understood the concept of the meter, and so i tried it with a 4017 as a drive for the 4066. however i am not sure if it is a simulation problem, it seem to work in a weird way.

generally what i did is 1Mhz --> 4017 --> select pins to use to trigger/sense
using 6 of the output to split 1 cycle (of 100kHz) into 3 parts of +ve/-ve trigger (cyan waveform), and then 2 of the 3 parts as a "sense" trigger (magenta/blue waveform). did i do this in the correct way? (ignore the incomplete opamp at the sense end)

Hi,

The original version that was described in the beginning of this thread and is presented in this message:

https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/msg391885/#msg391885

works fine. It is certainly good enough to sort out good and bad capacitors in and out of circuit.

A proposal was made to improve the performance by blanking the measurement during part of the measurement cycle. One way to implement this is with a 4017, like you have done. I have not built this circuit with the blanking, because the improvement is probably academic.

My original version uses 74HC4053 for the analog switches. The HC part is important, they are significantly faster than the non HC versions.


If you are interested I suggest building the original version.

Regards,

Jay_Diddy_B

[hugo]

Hi Jay_Diddy_B:

What is the purpose (value) of the potentiometer R22 ?

Thanks

[Jay_Diddy_B]

Hi Jay_Diddy_B:

What is the purpose (value) of the potentiometer R22 ?

Thanks

The value of R22 is 500 Ohms.

R22 is used to adjust the ESR meter adapter. I typically use a 1 Ohm resistor and adjust R22 for an output of 0.1 volts.

I made a test fixture like this:





Regards,

Jay_Diddy_B

[SeanB]

I like that test fixture, very nice. When I built my ESR meter I just used some 1R resistors to write the calibration points on the meter face using a Rotring pen, using a 0.5R, 1R, 2R 5R and 10R calibration points on the non linear scale. 3R is about half scale, and it works good enough to test capacitors.

[Edwin G. Pettis]

The problem is not your meters, per se, with the exception of low resistance, the 'Q' of a wire wound resistor rapidly drops to virtually zero at low frequencies and higher values, approximately somewhere in the range of 50 to 150 ohms, the 'Q' drops below 1 and for all intents and purposes, there is no inductance, it is totally swamped by the resistance.  At higher frequencies, it is mostly parasitics that your meters are reading because the 'Q' of a wire wound resistors varies little with freqency.  I have used several different bridges in researching the inductance of wire wound resistors, including calculations of inductance based on actual windings of equivalent copper coils vs resistor alloys.  Have you ever noticed that good inductors always have low resistance to keep the 'Q' high?  When you replace copper with resistance alloys, the 'Q' plunges even for exactly the same size of wire and turns on the same core.  No 'Q', no inductance, there has been some arguments to the contrary but the measurements are what they are, unless you're using wire wound resistors at high frequencies (the effect varies with the type and resistance a lot), you aren't going to see inductance and what you're seeing is mostly parasitics of inductance and capacitance.  I did many measurements while I was at Ultronix (and Ultrohm Plus) plotting the effect of frequency on actual 'resistance/impedance', in most cases the DC resistance was mostly unchanged until the frequency was well over 20KHz, mostly over 50KHz or even 100KHz before parasitic effects showed up.

The inductance of wire wound resistors is mostly well overstated!

[Jay_Diddy_B]

Is R21 meant to be zero?

R21 is a zero Ohm resistor. It is used as a jumper. The layout is single-sided. The circuit is built on the back of the front panel.

Jay_Diddy_B

[DJMota]

Great proyect!
Jay_Diddy_B Where i can buy the pcb of this proyect?
Thank for share it!

[cat87]

Thank you Jay_Diddy_B

Just finished building the adapter this weekend and recently I had the opportunity to  test it out against a Hameg HM8118. This baby will do 75 KHz and 100KHz measurements and I was really pleased to see that for some caps, the adapter was spot on (<5% accuracy) which is pretty satisfying. For some other no-name caps, the readings were kind of off. I don't know why, but I suspect the caps were the ones at fault here, not the ESR adapter.
So, for a quick go-no go type of measurement, it's perfect.

[Jay_Diddy_B]

Thank you Jay_Diddy_B

Just finished building the adapter this weekend and recently I had the opportunity to  test it out against a Hameg HM8118. This baby will do 75 KHz and 100KHz measurements and I was really pleased to see that for some caps, the adapter was spot on (<5% accuracy) which is pretty satisfying. For some other no-name caps, the readings were kind of off. I don't know why, but I suspect the caps were the ones at fault here, not the ESR adapter.
So, for a quick go-no go type of measurement, it's perfect.

Thank you for your kind words.

Can you post a picture of your version?

Regards,

Jay_Diddy_B

[cat87]

Sure thing. Sorry for the delay, but I'm moving house right now, and things are...well, all over the place.

This is how mine turned out:

[lpc32]

Anyone knows of a similar ESR-to-voltage adapter available on eBay?

[Jay_Diddy_B]

Hi group,

I have used up all the PCBs from the original batch that I had made by iTead.

For these I paid a premium to get black boards. You can see pictures of the boards in this message:

https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/msg372155/#msg372155

Questions

1) Would there be any interest if I made the blank board available?

2) Is worth the extra money to have it black instead of green?

3) Should I remove the 4 wire feature and make it 2 wires only?

I am not promising anything this just a quick survey.

I would ship by Canada Post. You can check the shipping charges to you location here:

https://www.canadapost.ca/cpotools/apps/far/business/findARate?execution=e1s1

Regards,

Jay_Diddy_B

[quarks]

Hello Jay_Diddy_B,

Great work
I think many of us would like to have such a nice ESR adapter from you

to your questions
1) yes
2) I would prefer black
3) I would prefer 4wire

Maybe you should make a poll for this

bye
quarks

[KD0CAC John]

Yes
Yes
No

[lpc32]

Hey Jay. Thanks for the design.

1) I was thinking initially of one of those $10-15 AVR Transistor Testers/component identifiers, so I'd prefer a populated device or in kit form. But a cheap enough board might still be interesting, especially thru-hole.

But I guess being in Canada makes it more expensive, combined with the cost of small scale production, and more per-item work/overhead required on your part. On the other hand, I think there should be a market for a complete cased device if priced right. On the other other hand, someone in China might start producing clones.

2) Functionality and price are more important to me than looks.

3) 4 wire as an option is better. Even if you don't use daily it doesn't add much to the BOM.

Speaking of BOM, maybe these cheapo 4mm jacks can work. Hopefully they're not too crappy:
Black: http://www.ebay.com/itm/221637907699
Red: http://www.ebay.com/itm/221606765590

Can anyone suggest an eBay/China-available cheap opamp alternative?

[LA7SJA]

Hello Jay_Diddy_B

I have made a through-hole veroboard version that sort of work, but I would like to build/buy two of your smd design. And a big thank you for getting me interested in LT-Spice.

Back to your questions.
YES I am interested in at least two pcb's.
YES I would pay extra for Black.
4W is the best! Maybe you could leave the 4W undrilled (or just a pilot hole) so the builder can deside when building and even "upgrade" at later stage.

Johan-Fredrik

[Shock]

I reread the thread to refresh.

1. I would still like to see you offer a kitset or built option as chasing the parts here in Australia is an expensive exercise. You could still do all three (kitset/built/pcb) if you really wanted to. I'd buy another prebuilt depending on inclusions to the design.

2. The black color looks good to me. But what percentage of the PCB cost (before shipping) are we talking here? An increase in a dollar is less significant to the buyer than it is to the seller.

3. I've not tested the 4W, but if the 4W accurately cancels out the impact of the 2 wire test leads and produces enough benefit (I'd also throw in testing resistors into this basket) then I think keep it. There is also room to make custom adapter boards (zif socket etc) keeping 4 sockets may add a bit of stability to doing this kind of thing.

As for Oldways suggestions:
A compensation trim pot, and a 10/100 switch, juggling a few components. Anything that improves the design without losing features or accuracy is a positive thing (obviously within the realms of cost and simplification). So if you feel you can improve the design overall go for it. If you have to trade off accuracy, overload protection, or a feature, you have to weigh up the pros and cons after comparing them.

[dabbler]

Hello,

first thank you for sharing this project. I made a (mostly) through-hole version and when I first tested it, it seemed to work. I was getting the 100mV for a 1ohm resistor (after minor tweak of the pot), a then tried a few different caps that appeared to have somewhat reasonable vals. Before the first test I also double and triple checked that everything was correctly connected etc..

So after the test I removed the battery again and left the circuit untouched (in the same location where I tested) for a day, until I could buy a plastic box to put it in. I put it in the box, soldered the 1-pol switch and connectors for test leads to the prepared wires, the same wires to which I had clamped the test components and DMM earlier. Really nothing there that could've caused any kind of issues.

I then went ahead to try it, again with the 1ohm resistor, but now everything was dead. I wasn't getting any readings. After checking the circuit it turns out the 78L05 seems dead. It's getting the 9V in, but 0 comes out. So, first time it worked, I even measured the output during my first test, then without having done anything inbetween that in any way should be able to affect the functionality, the volt. reg. has died.

Now, I'm very amateur. If some device, typically older, breaks down I usually check for bad caps. I figured this tool could help me with that. Otherwise my usual "constructions" are in the form of a microprocessor and a few surrounding components, so my skills to determine what could've gone wrong are limited. Googling what might cause the volt. reg. to fail, the only normal thing I could find was that they don't like reverse current/voltage and typically you're suggested to add one or two diodes to prevent this.

The ua78L05 datasheet (http://www.ti.com/lit/ds/symlink/ua78l05.pdf) confirmed this, in section 8.2.2, and also mentions it can happen during startup. I'm not seeing this kind of protection in the ESR meter circuit, so I'm wondering is that reverse voltage situation not possible here? If not, does anyone have any idea what else could break the regulator? Could I add those diodes only and have everything else still working without changes?

Any hints would be greatly appreciated.

(I do have one regulator left, but it feels like simply replacing it doesn't fix the root cause and only risks breaking that as well. Then I'd have a problem because ordering new ones within forseeable future isn't in the books with the rediculous shipping costs around here.)

[Shock]

Test it out of circuit or isolated it in circuit so you can check if anything is pulling the output down. Then should should check everything else in the circuit, dozen resistors, handful of caps and diodes, easy.

Add the diode if you want. To test measure a few known resistors individually or a length of wire (something consistent). Then add the two resistors in series or parallel and see if they add up and makes sense (or double the length of wire). I think you get the idea.

Should you not know the wrath of your bench supply (overshoot and such) use a battery.

[ZeTeX]

Hello,

first thank you for sharing this project. I made a (mostly) through-hole version and when I first tested it, it seemed to work. I was getting the 100mV for a 1ohm resistor (after minor tweak of the pot), a then tried a few different caps that appeared to have somewhat reasonable vals. Before the first test I also double and triple checked that everything was correctly connected etc..

So after the test I removed the battery again and left the circuit untouched (in the same location where I tested) for a day, until I could buy a plastic box to put it in. I put it in the box, soldered the 1-pol switch and connectors for test leads to the prepared wires, the same wires to which I had clamped the test components and DMM earlier. Really nothing there that could've caused any kind of issues.

I then went ahead to try it, again with the 1ohm resistor, but now everything was dead. I wasn't getting any readings. After checking the circuit it turns out the 78L05 seems dead. It's getting the 9V in, but 0 comes out. So, first time it worked, I even measured the output during my first test, then without having done anything inbetween that in any way should be able to affect the functionality, the volt. reg. has died.

Now, I'm very amateur. If some device, typically older, breaks down I usually check for bad caps. I figured this tool could help me with that. Otherwise my usual "constructions" are in the form of a microprocessor and a few surrounding components, so my skills to determine what could've gone wrong are limited. Googling what might cause the volt. reg. to fail, the only normal thing I could find was that they don't like reverse current/voltage and typically you're suggested to add one or two diodes to prevent this.

The ua78L05 datasheet (http://www.ti.com/lit/ds/symlink/ua78l05.pdf) confirmed this, in section 8.2.2, and also mentions it can happen during startup. I'm not seeing this kind of protection in the ESR meter circuit, so I'm wondering is that reverse voltage situation not possible here? If not, does anyone have any idea what else could break the regulator? Could I add those diodes only and have everything else still working without changes?

Any hints would be greatly appreciated.

(I do have one regulator left, but it feels like simply replacing it doesn't fix the root cause and only risks breaking that as well. Then I'd have a problem because ordering new ones within forseeable future isn't in the books with the rediculous shipping costs around here.)

Have you put large output capacitance? Over 22uF? Try to put all protection requird for the regulator.

Sent from my Nexus 5X using Tapatalk

[dabbler]

Well, I feel like the biggest doofus right now... That must've been the dumbest chain of events. Please disregard my post above.   

But thanks for the replies!

[dabbler]

I also wanted to note that some resistors in the BOM from "Construction Notes 2.pdf" in this post have conflicting values with their counterparts in the schematics of the same post.

R3: 6.8k in BOM - 6.2k in schematic
R6: 1.6k in BOM - 1.3k in schematic
R8, R17: 475 in BOM - 470 in schematic

I don't know what impact that would have if any, but it could be a bit confusing to someone like me and even causing the purchase of the wrong components (again for someone like me ).

[Jay_Diddy_B]

I also wanted to note that some resistors in the BOM from "Construction Notes 2.pdf" in this post have conflicting values with their counterparts in the schematics of the same post.

R3: 6.8k in BOM - 6.2k in schematic
R6: 1.6k in BOM - 1.3k in schematic
R8, R17: 475 in BOM - 470 in schematic

I don't know what impact that would have if any, but it could be a bit confusing to someone like me and even causing the purchase of the wrong components (again for someone like me ).

R3 sets the operating frequency. Traditionally 100kHz is used for ESR measurements. A small difference in frequency does not change the ESR reading.

R6 is used to centre the calibration pot. You need to change R6 if you are unable to calibrate the adapter.

475 versus 470  The small change in value comes from 1% resistors come in E96 values (475) and 5% resistor in E12 and E24 values (470)
Either value will work.

Regards,

Jay_Diddy_B