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Tonghui TH2821A LCR Meter

Discussion in 'Electronic Design' started by Mike, Nov 1, 2011.

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  1. Mike

    Mike Guest

    Here's something that may interest some folks here. I just got my new
    Tonghui TH2821A LCR Meter, and I'm starting to become quite impressed.

    After some screwups due to a discharged internal battery and not reading
    the instructions, it is starting to give some really impressive results.

    5 digits resolution on 1000uf caps, 4 digits on iron-core inductor,
    miscellaneous resolution on 30k resistors (I haven't figured out how to
    measure resistance yet, but it should be very easy:)

    Here's the eBay info:

    LCR RCL LC Meter TH2821A inductance Capacitance 10kHz

    Price : US $164.93
    Shipping : $25.00
    Item : 320492041898

    It can measure 6 basic parameters: inductance L, capacitance C,
    resistance R, impedance Z, dissipation factor D and quality factor

    It has measurement accuracy of 0.3% and 4-bin sorting.

    Applied complete 5-terminal measurement configuration solves problem
    of measurement for equivalent series resistance and capacitor with
    small dissipation that other portable LCR meters can't solve. It can
    replace general low-frequency LCR meter.

    Only portable LCR meter at home
    Large LCD display
    Measurement frequency up to 10kHz
    Basic accuracy: 0.3% with resolution of 0.01%
    5-side measurement technology to provide accurate measurement of ESR
    and loss
    Sweep Clear Function
    battery and external power supply power supply
    fourth gear sorting

    Measurement Signal

    Signal Frequency : 100Hz 120Hz 1KHz,10KHz
    OutPut Impedance : Dependent on range
    Test level : 0.3Vrms

    Measurement display range

    R : 0.0001Ohm ~ 99.999Ohm
    C : 0.01pF ~ 9999uF
    L : 0.01uH ~ 9999H
    D,Q : 0.0001 ~ 9.9999
    ?% : -999.99% ~ 999.99%


    Comparator : 4bins: NG, P1, P2, P3 with beeper alarm

    You can also get smd tongs:

    US $36.00

    Item : 350502463639

    The manual is dated November 2005, 1st Edition Rev 1.0.0

    " Operation%


    " TONGHUI TH2821.pdf"



    You can also get the TH2821B, which goes to 1KHz

    Item: 350501591362

    Price: US $136.00

    The only problem so far is they shipped a 220VAC adapter, which does not
    work on 120VAC. After some discussions, they shipped a universal 100-
    240VAC adapter which should work anywhere. If you want one, be sure and
    tell them to ship the universal 100-240VAC adapter. But they are very
    nice to deal with and you should have no problems.

    For the performance and price, I don't think you can beat this anywhere.
    I especially like being able to measure ESR of large electrolytics, since
    I have a lot of eBay boat anchors that need some care.

    So far the performance is excellent. I'll post if I come across any


  2. Mike

    Mike Guest

    The resistance measurements are now OK once the internal battery is
    charged. This issue is mentioned in the manual. The unit comes with the
    battery discharged, so you just have to wait until it is charged before
    starting to play with it.

    It gives 4 digits of resolution on a 30k resistor. This is adequate for
    most ordinary needs.

    Altogether, I'm very pleased. It has already identified a bad electrolytic
    in a circuit where there are several that could be causing the problem. The
    rest are fine.

  3. Mike

    Mike Guest

    The TH2821A appears to be discontinued, but there may still be some stock
    left on eBay.

    The replacement is the TH2822C, which goes up to 100KHz and offers
    averaging, 40,000 counts, 16 hours operation on internal battery, TH2822C
    has optional rechargeable batteries, Standard Mini-USB interface, etc.

    Here's the feature list:

    * Basic measurement accuracy: 0.25%
    * Gorgeous dual-color cast shell
    * Maximum test signal frequency: 100kHz (TH2822C)
    * 40,000 counts for primary parameter, D/Q resolution 0.0001
    * Typical ultra-low consumption : 25mA
    * Battery capacity: TH2822/TH2822A continuously used for 16 hours
    * TH2822C rechargeable batteries are optional
    * Innovatively compatible terminal configuration : 5-terminal test
    slot and 3-terminal banana jack
    * Intelligent Auto LCR function
    * Measurement speed up to 4 meas/sec
    * fast automatic range switch design
    * Constant output impedance: 100 Ohm
    * Percentage display and 4-tolerance comparator: 1%, 5%, 10%,
    20% (20% not available for TH2822)
    * Automatic OPEN/SHORT correction detection
    * Data Hold, Max/Min/ Average recording
    * Utility function configuration and current setup recovery after
    * Standard Mini-USB interface, SCPI compatible
    * Firmware update through Mini-USB interface
    * Free FastAccess communication software on our website

    The web page is

    The TH2822C are vailable on eBay for around $474.70

    It looks like the TH2821A is a pretty good deal for the price, if you can
    still get one:)


  4. John S

    John S Guest

    You talked me into it, Mike. The specs look super to me and I've been
    needing something like it.

    Do you get probes with it so you can test components on a populated board?

    Thanks for the find.

    John S
  5. Mike

    Mike Guest

    Which one are you getting - TH2821A or TH2822C?

    The SMD probe I mentioned earlier is for the TH2821A. It is
    available on eBay:

    Price: US $36.00
    Item : 350502463639

    It won't work on the TH2822, but they should have something that
    does work.

    For populated boards, of course you have to watch for other
    components in parallel. But the measuring voltage seems to be too
    low to turn on silicon junctions, so it should work OK in most

    I was afraid of accidentally testing a charged electrolytic, which
    is how I destroyed my last capacitance meter. So I tried adding a
    fast silicon diode in parallel with a large electrolytic.

    As far as I can tell, it has little or no effect on the reading. But
    it makes the instrument go nuts when there is no electrolytic
    capacitor to measure. I will make a little test fixture that adds
    two fast 3A diodes back-to-back in parallel with the test probes to
    try to avoid making the same mistake in the future.

    I find sometimes the reading on the TH2821A fluctuates a bit. You
    have to find the correct test frequency for the component you are
    trying to measure.

    I would really like the ability to average the readings, which is
    provided in the TH2822C. But the price is way more than I am willing
    to pay.

    Once it gets to that level, I seriously start thinking of making my
    own unit. With the components available to us these days, it should
    be possible to beat the performance of almost anything on the

    For example, there are two vector network analyzers available on the
    web that you can build yourself. Both are in the Yahoo forums, and
    they seem to be very good instruments. But already there is a much
    better version of the DDS than the one they are using. That should
    improve the performance substantially.

    There is also a spectrum analyzer you can build yourself. But I
    happen to have a 8566 so that is not too interesting at the moment.

    The only problem is if the 8566 dies and needs some unobtanium part.

    That already happened to a HP 8505 network analyzer that I bought
    new, and was discontinued the week after I paid cash for it. It ran
    for a number of years, then it died. It would have cost too much to
    get it repaired, so I just put it in a dumpster and promised myself
    I would never buy another expensive instrument. Either get it on
    eBay for pennies, or build it myself.

    Ultimately I would rather have my own stuff. It will take much less
    room on the bench, have usb interface for control, and be much
    easier to repair or upgrade as time goes on.


  6. P E Schoen

    P E Schoen Guest

    About four years ago I purchased a similar unit, the MCP BR2822 LCR BR2822.html
    I paid $250 for it and except for some problems with the battery, it seemed
    OK. But I have not used it much. I think I got it from these guys:,
    who now want $349 for it. Amazon has it for $300.

    I also bought a $50 LCR that I use for everyday purposes:
    It's OK, but sometimes I have to fiddle with the switch and/or the leads to
    get continuity.

    I'm waiting for delivery on:

    I'm considering the following unit:
    or maybe this:

  7. Mike

    Mike Guest

    That looks identical to the TH2821A!
    Yes, I have a bunch of dmms. Some measure capacitance, but none measure
    ESR. You need that to weed out the bad electrolytics in eBay boat
    For the function generator, I've pretty much decided to go ahead and make
    my own using a DDS. You can get microhertz resolution, 0 to 250MHz sine
    waves, and USB interface. I think you can get frequency sweep and other
    functions, and add your own limiter for square waves. Put two in the same
    box for intermodulation testing and mixer development. Add external
    filters for high purity sine waves for harmonic distortion. Run it off a
    GPS-stabilized reference for the ultimate in frequency stability.

    The main thing is you can't predict what you may want to do, so having
    the flexibiity to modify your own generator is much better than getting a
    commercial unit that may not have the fundamental accuracy and stability
    you need. You might be reluctant to modify a commercial unit, or maybe
    you don't even get the schematics. But if it's your own, that is no


  8. John S

    John S Guest

    Thanks. I'll look into it.

    John S
  9. John S

    John S Guest

    BTW, these are also available for those large, TH electrolytics already
    on the board:

    Item 320702317637

    John S
  10. Mike

    Mike Guest

    Good News - those came with the TH2821A.

    I have been trying to figure out how they make them into Kelvin contacts.
    The contact pads are two sided pcb. I think they may use one side for the
    exciting signal and the other side for the sense. It appears they do the
    same with the clips, since there are separate leads going to each side.

    I put a thin dab of vaseline on the contacts. That provides a bit of
    lubrication to minimize wear. It also removes the surface oxides and grime
    and allows a true metal-to-metal contact. This reduces the contact
    resistance by a factor of ten and stabilizes it. Old radio engineer's trick
    from the 1930's


  11. Mike

    Mike Guest

    There are numerous eBay vendors that still offer the TH2821A. The prices
    vary quite a bit, but it looks like dealexcel-com has the best offer at the
    moment. They want US $185.65, but the shipping is now free. That's where I
    got my unit, but the shipping was extra.

    If you are interested in getting one, I'd go with them. They already know
    about the problem with the 220VAC adapter not working in the US, and they
    shipped a replacement that goes from 100VAC to 220VAC so it should work

    They send the Kelvin clips with the unit, so you don't have to buy them
    separately. They also handle the smd probe, so you can combine the entire
    order in one package.


  12. ehsjr

    ehsjr Guest

    Mike wrote:

    You can build a go/no go ESR "meter" that'll find the bad 'lytics
    for next to nothing. Worth doing, unless you (psychologically)
    _must_ have a "real" esr meter.

  13. Mike

    Mike Guest

    You talked me into it, Mike. The specs look super to me and I've
    Sorry, John. I completely missed your question for some reason. Just
    to confirm, the TH26027 Kelvin test cable probe comes with the
    TH2821A. It is listed as an accessory on page 4 of the Operator's


    and also listed in the datasheet:


    I checked the continuity from the two-sided contact pad to the test
    clip. The connections are all individual and separate from each
    other, so it is a true Kelvin connection all the way to the

    Pretty good for a $185US instrument!

    Just make sure you get the Universal 100-220VAC adapter.


  14. John S

    John S Guest

    Well, I already bought another set. But, that's okay.

    Maybe I'll send him an email to remind him.

    Thanks for the clue.

    John S
  15. Mike

    Mike Guest

    You talked me into it. I can think of several projects where this would
    come in handy. You can never tell when these things will disappear, so I
    got a set also.

    Thanks for the pointer!

  16. John S

    John S Guest

    I had a tiny amount of respect for you until you pulled this crap out of
    your ass.
  17. John S

    John S Guest

    I hope you die wondering. Soon.
  18. I think it is a Bot, probably Japanese origin from the English and
    grammar it uses.

  19. josephkk

    josephkk Guest

    D you are a brain dead twit.

  20. John S

    John S Guest

    You are. And, josephkk is right; you are a brain dead twit. And what the
    hell business is it of yours?
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