Sunday, July 8, 2012

Advanced LC meter

After finishing my last project - "Simple LC meter", there were some discussions in the forum I am a member of, that ability to measure electrolytic capacitors would be very useful in this type of device.
I searched the Web and found a very cute project named LCM3 on this Hungarian site: hobbielektronika.hu . I love Hungarian rock since my school days, but I don't know a word in Hungarian :( . So, I searched the Web again, this time for this specific project and found a Russian forum where the project was discussed in details and I got more useful information about parts, settings and so on.

Specifications of the LCM3 are (according to authors of the project):
Capacitors:
from 1pF to 1nF - resolution: 0.1pF, accuracy: 1%
from 1nF to 100nF - resolution: 1pF, accuracy: 1% 
from 100nF to 1uF - resolution 1nF, accuracy: 2.5%
Electrolytic capacitors:
from 100nF to 100 000uF - resolution 1nF, accuracy: 5%
Inductance:
from 10nH to 20H - resolution 10nH, accuracy: 5%
Resistance:
from 1mOhm to 0.5Ohm - resolution 1mOhm, accuracy: 5%




So, I put the schematic in Eagle and this is the result:


As usual I designed a new PCB. The PCB is designed in such a way, that it is possible to mount the LCD display on top of the board. The multiturn trimmer for adjusting the contrast is bellow the display, so it must be of this type : 
Тhere is also an option for mounting a 3-pin terminal connector, so it's possible to use the whole device without an enclosure.

All resistors are 1% metal film. Two 1nF capacitors are 1% styroflex. CX1 - 33nF is also critical - this must be polypropylene high voltage capacitor. I tried with two types: 10% X2 275Vac and Panasonic 3% 800V - worked fine with both.  The inductor must be with low Rdc. There is a connector for a separate adapter, which bypasses the ON/OFF button. Maybe on next revision of PCB I would add an onboard power connector.
If the device is powered with external power adapter, you may increase back light current by decreasing the value of the resistor R11. You must consult with the datasheet of the display to select a proper value of the resistor.

I must warn you - capacitors MUST be discharged before measurement or there is a danger of destroying the chip.

Here is the final result. This is the second unit I built:

























As you can see on the last photo, it is possible to measure small value resistors,
which is a nice bonus :)

Link for downloading project files in PDF: LCM 3.rar
Use them on your own responsibility.
Link for downloading hex file (on the bottom of the page).


Update: 08 June 2013
Recently I found in one of the local web stores an enclosure which I  thought would be perfect for this device. As it turned out this wasn't the case :(
So I bought it and when it arrived I found that the internal width of the enclosure was insufficient for normal LCD 16x2 displays. I started looking for smaller displays and found out that it is hard to find such devices and they are very expensive.
Anyway, finally I bought the only one available (but three times more expensive) display and made a new PCB for this particular case and display. The schematic is the same as above.

Here are some pictures of my new LC meter:





Expensive styroflex 1nF/1% capacitors.

For bigger inductance the meter shows parasitic capacitance.





60 comments:

  1. Здравей, каква е цената за един брой от изделието по-горе?

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    Replies
    1. Зависи какви части ще ползваш. Около 40 лв. излизат частите, които аз ползвам. Кутията е още към 12-13 лв.
      Ако питаш за колко аз бих направил по поръчка - 80лв.

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  2. test
    1 час не мога да разбера как да напиша един прост коментар на блог, най накравя успявам сега ако успея да на пиша грозната кепча картинка и разкривените букви правилно теста ще е успешен


    Здравей! Имам няколко въпроса защото много исках да си направя LC meter! Първо: защо излизат толкова скъпо частите? ПИК-а във Farnell не е толкова скъп. Аз си мислех ч максимум 10-15 лева отиват за частите без кутията. Дисплеите са по няколко долара в eBay.
    Както и да е да оставим цената на страна
    Други въпроси: бутоните какви са: натискаш еднократно и се връщат или като ги натиснеш остават в натиснато положение? 1вия е за включване, със втория се избира режим LC а с третия се избира режим калиброване? (с точен кондензатор)
    Първо реших да правя първата схема, но после видях че тази мери малки резистори, и това е бонус.
    ДРУГ ВАЖЕН ВЪПРОС: какъв дисплей се ползва за първата схема и съответно какъв за тази? Първата пише ще може да работи с 16x2 и с 16x1, това какво ще рече? Ако позлвам дисплей с 2 реда ще виждам ли допълнително 2ри ред с цифрички (информация) или не?
    Реално МИкроконтролера показва само 1 ред?
    СЪЩИЯ въпрос за 2рата схема: там се вижда че като че ли е задължително да се ползва дисплей с 2реда?
    И ПОЛСЕДЕН ВЪПРОС (поне засега) Какви са обхватите на 2та реда за мерене на L и C? Кой уред има по голям обхват и кой е "по-точен"?
    Благодаря предварително с нетърпение очаквам отговори!

    ReplyDelete
    Replies
    1. Цената е относително нещо, зависи от курса на долара, примерно. Предполагам, че може да се намерят и по-евтини части. Освен това в крайната сума съм включил и изработката на платка.

      Бутоните са два задържащи - за L/C и за ON/OFF и един незадържащ, който е за RESET (средния бутон).

      Дисплея за LCM3 задължително е двуредов, докато за по-простия LC метър може да е 1 или 2 реда, защото информацията, която се показва реално е само на 1 ред.

      За точността не мога да кажа, защото нямам еталонен уред, с който да ги сравня.
      Обхватите и точността на LCM3 можеш да видиш на този линк: http://www.hobbielektronika.hu/cikkek/lcm3_alkatresz_mero_muszer_-_kit_lehetoseg.html?pg=3
      Точността, дадена в таблицата предполагам е само ориентировъчна. Избора на части и направата на платката оказват голямо влияние.

      И на другия въпрос - не няма разрядник. Кондензаторите задължително трябва предварително да са разредени.

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  3. + още нещо: първия LC meter в блога има ли разрядник, демек с него мога ли да меря заредени кондензатори без да го повредя?

    ReplyDelete
  4. А кой hex файл трябва да се ползва за PIC-a, от унгарския сайт или друг от руския. Ако може добави линк и за него в блога.

    ReplyDelete
    Replies
    1. Аз ползвам последната версия - 1.35 от унгарския сайт.
      Ето линк: http://www.hobbielektronika.hu/cikkek/lcm3_alkatresz_mero_muszer_-_kit_lehetoseg.html?pg=7

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  5. how much the bill of material? where to buy styroflex. capacitors and L1 online? thx

    ReplyDelete
    Replies
    1. It costs about a 25-30 USD with standard 16x2 LCD display and without enclosure.
      Styroflex is brand name for polystyrene.
      The capacitors I use can be found in Farnel and Newark.
      http://www.newark.com/lcr-components/fscex-1000pf-1-250v/capacitor-polystyrene-film-1000pf/dp/74K0403

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    2. This comment has been removed by the author.

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    3. hi christo do u have an email? thx

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    4. You may write me at "xristost" in yahoo.

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  6. where i can download the Hex File For This Advanced LC meter

    ReplyDelete
    Replies
    1. I have updated the post and added the link for downloading the HEX file.

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  7. Hi

    I am newbie for PICs. In fact, this would be my first project.
    I could not find 16F690 in local market. Is it possible to use some other PIC ? If yes, what other PICs can be used.
    OR Is a program designed for a specific PIC?

    ReplyDelete
  8. It's not my project, so I can't answer you for sure. Maybe it can be used another PIC microcontroller, but for sure there must be another PCB and another program code.

    ReplyDelete
    Replies
    1. Can you please let have the contacts of the original author? I could not find any link at the Hungarian site. Maybe, he can rmodify the course and get me new HEX file for some other PIC.

      Delete
  9. Hello admin,
    I have built this Advanced LC Meter, previously i had the Simple Version of this LC meter,
    My Advanced LC Meter seems to have some problem, that i hope you could resolve.
    Im able to measure Electrolytic Capacitors with a good accuracy, but it doesnt displays the ESR for Electrolytic Capacitors, instead displays a ? mark.
    Also it is unable to measure Bipolar Capacitors & Inductor values & displays some random values. But it does measure them.

    I have used a 100uH Inductor, the one's that look like a resistor with colour code's. I measured it's resistance and seems to have effective resistance, even higher than those inductors which i made by winding a 22AWG wire on a toroid (350uH).

    i think this resistance is the problem, cause you have mentioned the Rdc must be very low.
    I understand, its not your own project to make any remarks on it.
    If possible kindly suggest any modifications.

    ReplyDelete
    Replies
    1. Hi,
      Did you calibrate the meter before measurement? If you not, maybe this is the problem. In "C" mode, connect the test probes as for measurement the electrolytic capacitors and short them. Then press and hold the "RESET" button until the message "Switch to meas." appear and then release the button. Note the Uesr value shown on the screen.
      Now the value "Rx = " must be around 0 Ohm (±10mOhms) when the test probes are shorted.
      Calibrating the LC meter in the "L" mode is the same - only test probes are plugged to the "GND" and "L/C" connectors and shorted again.
      Now, if the Rdc of the inductor is too high the Uesr will be high and the accuracy will be low.
      On my LC meter the Uesr is 108mV. I suggest to replace the inductor. These coils that looks like resistors are not good for this schematic. They usually have Rdc higher than 1-2 Ohms. On my LC meter the inductor's Rdc is 0.18 Ohms.

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    2. Hi Again, i finally got it working just when i was about to give up.

      The actual problem was 1nF Styroflex Capacitor that formed the resonant circuit. It's value changed uncertainly thereby causing measurement errors. Replaced with another Capacitor and Device is working like charm.

      Im amazed with the accuracy of this meter. Its really fun playing with.
      I also replaced the inductor by a 100uH Choke that i made by removing some turns from 1.8mH Choke, lol.

      Thank you for your support admin, im successful with two of your projects now : )
      Keep Posting such wonderful projects.

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  10. Hi

    Can you please provide the Eagle files of the circuit, I want to make some changes in the PCB according to parts I received.
    My Eagle does not have PIC16F690 model. Thanks for the help.

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  11. Hi

    You used a DPDT switch for calibration, can we use a SPDT switch?
    How the calibration is done?

    ReplyDelete
    Replies
    1. Sorry, I forgot to answer your questions.
      First, I did not give Eagle files. In standard libraries some parts are missing, for example this particular PIC, but u can make it in library editor as I did. Also you can search for user-made libraries in eagle site:
      http://www.cadsoftusa.com/download-eagle/libraries-dev/
      There for sure you can find PIC16F690 and many other missing parts.
      Second. You can use SPDT switch as the second part of DPDT switch in the schematic is not used at all. Of course you must change the PCB to incorporate the different parts.

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  12. HI to program this pic 16f690 does it has to be a pikit2 or do u know another pic programer that is comparable with 20 pins pics I have a pic programer for any pic but this one do u know any schematic for a pic programers to program this pic. I when to Google and couldn't find any suitable one. Can you help me plz tank u very much

    ReplyDelete
    Replies
    1. Before I made my clone of PICkit2, I used a cheap chinese programmer like this:
      http://www.ebay.com/itm/PIC-K150-USB-Automatic-Microcontroller-Programmer-ICSP-Download-cable-New-/271276024502?pt=LH_DefaultDomain_0&hash=item3f294fa2b6
      It can program 16F690, but only in ICSP mode. The problem is It's software is pain in the ass to configure and to use.

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  13. Sir What is the specification of the relay switch and L/C, power switch.

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  14. Sir please tell me the range of this meter.

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  15. sir in your advanced lcr project what is the function of JP2 ICSP , and X1, X2. and how to use those,how to make calibration of these meter. please help me.

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  16. I have built this Advanced LC Meter, previously i had the Simple Version of this LC meter,and it work great I love it.Now this one when I turn it on it says CALIBRATION corrupted I try to fix it if you know how to fix this can give some advise please it will be appreciated thank you very much

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  17. Dear Sir,

    I build this device with exact specification of the part but I can't get it to work properly.
    I start the device, did the calibration ant it states "Switch to meas" for both Cx and Lx modes. Then when trying to measure Cx I get nothing, just C, or ESR or LX = ?. I rechecked soldering and part one for one but can't get this device to work. Any help??

    ReplyDelete
    Replies
    1. Hi, something similar happened to one of LC meters that I build for a colleague. He measured charged capacitor and the input pin of microcontroller was destroyed. It appeared to be OK because I was able to program it without errors, and when powered it seemed to work, but it didn't measure anything. Replacing the microcontroller fixed the problem.
      Another problem might be disconnection or poor connection between the probes and the PCB. These links must be with very low resistance.
      And of course check again all soldering points and PCB tracks. It will help if you clean the bottom side of the PCB with some alcohol or other appropriate cleaner.

      Delete
  18. Any chance to get the pdf files for the newer version in your post, at least with less components?

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    Replies
    1. Do you mean the LCmeter with black case? It is the exact same schematic with exact same number of components and the display is not standard so the PCB will be useless for most of the people.

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    2. Yes exactly the one with black casing, it seems having less components, resistors and diodes.

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    3. As for the display I have such one, If it not a trouble for you to provide the PDF files. I would be extremely thankful.

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    4. Be sure it is the same : LCM-S01602DTR/M
      INFO: http://www.lumex.com/lcm-s01602dtr-m

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    5. The one I have is salvaged from Xilinx ML401 which is the same compared to one you provided. Haven't actually tested it yet but I don't suspect it to be dysfunctional. So any chance to provide files?

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    6. Hello again, Any news about the files? can you send them over?

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    7. Hi, I am busy right now, will upload files in couple of days.

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    8. Thanks a lot for all help.

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    9. Hello again, any news about files? Hope I'm not bothering you with my request.

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    10. Hi, you can download files from this link: http://bit.ly/1MZhSVw

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  19. Малко тестове с кондензатори с нисък ESR:
    https://www.youtube.com/watch?v=6KhZVJ6lv2I

    ReplyDelete
    Replies
    1. Откъде ги взимаш тези кондензатори? Не съм виждал по нашите ширини такива (освен в компютърните дъна).

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  20. Здравей, предлагаш ли все още готови такива уреди и на каква цена ги предлагаш

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    Replies
    1. Здравей,
      Цената на уреда е 80 лв. За съжаление, в момента в Комет липсват кутиите които ползвам. Алтернативите са да ти направя уреда без кутия за 65 лв. и сам да измислиш някаква кутия или да се ползва друга кутия от Комет със съответната корекция на цената. Вариантите за кутии не са много за съжаление. Ето какво може да се ползва (цените са без ДДС):
      https://store.comet.bg/Catalogue/Product/23696/
      https://store.comet.bg/Catalogue/Product/23932/
      https://store.comet.bg/Catalogue/Product/25466/

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  21. Thank you for putting this project on the Internet for free. This is a great help to other electronic hobbyists!

    ReplyDelete
  22. Отличный проект. Мне очень понравилось, но все еще не мог заставить его работать правильно. Он представляет множество негативных результатов. Вы могли бы сказать мне что-нибудь? Спасибо.

    ReplyDelete
    Replies
    1. I can't tell you anything without more information from you! What exactly is the problem? Is the PCB was made from my design or you made your own design? Are all the parts exactly the same as described here? Are you calibrated properly the LCR meter?

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    2. Thanks for attention. I did exactly the same as your project, using the same recommended components. Measurements capacitances (electrolytic capacitors, ceramic, Tantalus, polyester, etc.) are good, but the ESR has some negative values. But what I think is abnormal inductance that is always with negative and values close to Lx = -619.0 uH. If you can help, thank you very much. You can send you the address of the Russian forum that discussed this matter? Thank you very much.

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    3. I forgot to say I did the calibration as recommended in your article. Thank you very much.

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    4. What value you get when short the test leads in 'L' mode? You should get around 0.0 uH. If you not, then press and hold the RESET button while the test leads are shorted. Release the RESET button when on the screen appear the message "Switch to Meas.!". Now, when shorted, the meter must show zero or close to zero value.

      The procedure for the ESR is similar. The test leads must be connected to GND and EL connectors and the LCR meter must be in 'C' mode. Short the test leads and press and hold the RESET button. Release when on the screen appear the message "Switch to Meas.!".

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    5. Again, thank you for your attention and sorry for the delay in responding. It is that redid the project again, with selected components, but unfortunately the result was not good. I made a video using LCM and would like to arrange for you to take a look if you have time. Could you send me an email where I can send the video? Again my thanks.

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    6. My email is on the "About" page. You can send the video to that address.

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  23. Hello Христо.
    Can you upload the PCB for LCM V.4?
    Thanks for your work :)

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  24. Hi,
    I made this project and it works fine,but I don't anderstand "m20" when I test an electrolytic capacitor.
    can you tell me what is "m20" please?
    Thank-you

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  25. Hi
    thanks a lot for share , but i have i question please
    in the link for downloading the hex file , there are many versions ( 6 versions ) , which one is working fine with this hardware design ?
    thanks for any help given

    ReplyDelete