Measure small inductances - Page 1
Forum section: electronics / general

author: T_guttata
author_rank: Regular Contributor
timestamp: January 28, 2022, 11:00:15 am
content: HiI'm looking for an LCR meter in order to measure small inductance values starting at around 5 uH. After some googling I found several devices:DER-EE DE-5000Seems to be the best value for the money, however, it seems hard to get. Is it still beeing produced? Are there any non-ebay suppliers? Is there any successor?Hantek 1833Chttp://www.hantek.com/products/detail/16180They claim an accuracy of 4% for the range of 0-4 uH. I did not find too many reviews.Keysight U1733Chttps://www.keysight.com/ch/de/support/U1733C/handheld-lcr-meter-100-hz-120-hz-1-khz-10-khz100-khz.htmlIt's too expensive for hobby.Peaktech P2175https://www.peaktech.de/uk/PeakTech-P-2175-LCR-Meter-11000-Counts-20H-110-mF-20-MO/P-2175They claimAccurate measurements from approx. 0.5Ω, 1nF or 10µH upwardsbut it only goes to 1kHzAre there more alternatives? Do you have any suggestions?What's about a different approach: function generator + DSO? O don't have a function generator yet but a Rigol DSOThanks for your help.Edit: I accidently posted in the wrong category, should have been in "Test equipment".

author: Berni
author_rank: Super Contributor
timestamp: January 28, 2022, 11:37:39 am
content: The DE-5000 is a really good LCR meter for the money. I think these mostly sell trough the ebay/aliexpress/amazon etc in general, not all companies want to deal with selling directly to consumers.5uH is not that difficult to measure so even the cheap 10$ 3 terminal autodetecting component testers(transistors,diodes,,caps,inductors etc..) will likely be able to measure it, they can do down to pretty low uH and pFYou can certainly use a signal generator, scope and some elbow grease to do a inductance measurement, it's just not very fun to do often as it needs quite a bit of setup and some manual math to actually get the result. The best instrument to abuse for this is a vector network analyzer since in the smith chart display it will typically show the resistance and reactance of whatever is connected. Some might show it as a complex impedance, but many will show it as farads or henries. This is typically a good way to measure very tiny reactance such as pF and nH because VNAs typicaly go up into rather high frequencies past 1 GHz so this makes such tiny reactance much easier to measure. So well sited for measuring say the capacitance or inductance of a PCB trace. However a VNA is much more expensive than a LCR meter, so its more of a thing if you happen to have one rather than buying one for this purpose.

author: PartialDischarge
author_rank: Super Contributor
timestamp: January 28, 2022, 11:38:09 am
content: I have the LCR200 from extech and actually like it very much

author: T_guttata
author_rank: Regular Contributor
timestamp: January 28, 2022, 12:03:29 pm
content: Well, even if the DE-5000 is very good, I don't want to buy from untrusted sellers. Therefore, I prefere to get one device which is highly available.Do you think it's possible to measure 5 uH with 1kHz?Then I could go with the Peaktech P2175. I have a power supply from this brand and I'm happy. They do good marketing as the products (and they have many devices) have a coroperate design.If that's not enough, the EXTECH LCR200 would be an option, but it's significantly more expensive (around US $275).There seem to exist several devices which use the same main IC:EXTECH LCR200Peaktech P 2170Lutron LCR-9184Tenma 72-10465UNI-T UT612Mastech MS5308Voltcraft LCR 300Axiomet AX-LCR42Aktakom AMM-3320ktakom AMM-3035Kusam KM-520B

author: bob91343
author_rank: Super Contributor
timestamp: January 28, 2022, 06:20:44 pm
content: I would use the nanoVNA. Or an obsolete boat anchor, Boonton Q meter or RX meter. I have both and they work well for small inductance, very accurate. You pick the frequency of measurement and get inductance and Q.

author: mawyatt
author_rank: Super Contributor
timestamp: January 28, 2022, 06:38:11 pm
content: Quote from: T_guttata on January 28, 2022, 12:03:29 pmThis would be difficult @ 1KHz since the inductive impedance is j*omega*L, and 5uH @ 1KHz is only +j 0.031 ohms. Much higher measurement frequencies would be better.Best,

author: bdunham7
author_rank: Super Contributor
timestamp: January 28, 2022, 06:52:50 pm
content: The recently discontinued BK Precision 885 and 886 will measure 5uH @ 10kHz with a specified accuracy of 1% and a resolution of 1nH. Not cheap, but you might find deals. The 886 will do 100kHz as well, but apparently it isn't needed for 5uH.The DE-5000 seems well liked by those that have it (I don't) and is much less expensive, although less accurate than the BK models--probably good enough for most uses though. Amazon has them in the US, I don't know your local situation.

author: T_guttata
author_rank: Regular Contributor
timestamp: January 28, 2022, 07:04:05 pm
content: Hm, the nanoVNA is still >$100 and I would not have any other task for it. If I get an LCR meter I can also use it to measure small DC resistances and caps.At the moment I tend to the Voltcraft LCR 300. I can get it from a trusted supplier and it's around $200. It has 4K wires and the possibility to measure without wires as well.https://www.conrad.com/p/voltcraft-lcr-300-component-tester-digital-cat-i-display-counts-20000-103677The LCR 400 would also be interesting but it's currently out of stock:https://www.conrad.com/p/voltcraft-lcr-400-component-tester-digital-cat-i-display-counts-20000-1301292What would you choose? 4K wires oder tweezers? The accessories do not seem to be compatible.The EXTECH LCR200 and Peaktech P2170 are 50% more expensive with similar specs. The DE-5000 is unfortunately only available on ebay (Japan). Or on aliexpress for $600^^

author: bob91343
author_rank: Super Contributor
timestamp: January 28, 2022, 07:42:25 pm
content: The nanoVNA isn't that expensive.https://www.ebay.com/itm/334305212520?hash=item4dd624b868:g:IB4AAOSwsBFheS2xFor around 50 bucks you get a very versatile instrument that can be calibrated accurately. It will measure any sort of component, L, C, R, transmission line, etc.

author: T_guttata
author_rank: Regular Contributor
timestamp: January 28, 2022, 08:44:55 pm
content: I will watch some videos to understand how the device works.

author: T_guttata
author_rank: Regular Contributor
timestamp: February 10, 2022, 09:21:14 pm
content: I decided to try out the Voltcraft LCR 300 (which is the same device as the Peaktech P2170) and I could test it doday.I have some mixed feelings about the device, but I don't know if more expensive devices (or the DE-5000) are better.Some issues i encountered:- After calibration the measured DCR is 0.03 Ohm when shorting the clamps. What's the point of having 4K clips and a calibration mode then?- I don't trust the ESR values. For various capacitors (1500 uF) the indication was 0.00 Ohm. Are todays ESR values too low to measure with LCR meters?- It looks like the device can not test capacitors with 1kHz (no indication)- I measured the capacitance of a bunch of electrolytic caps (different sizes, brands) and the indication was constantly quite low (1200 uF for 1500 uF cap, 800 for 1000 uF cap). The readings are possible, no question. But is it really likely that all caps are around 20% below the indicated value of the manufacturer?I was hoping that I could also measure DC resistances in the range of 1-10 mOhm, but this is not possible.

author: Electro Fan
author_rank: Super Contributor
timestamp: February 11, 2022, 06:02:32 am
content: Not inductance but here is a thread about resistance measuring. Might give you some insights on the DE-5000 (it is an excellent meter especially for the price) and some of the challenges as you measure values of about 10 milliohms to 1 milliohm and head toward 100s of microohms.https://www.eevblog.com/forum/testgear/4-wire-2-wire-resistance-tests-various-cheap-kelvin-clips-various-meters/msg3228660/#msg3228660

author: 2N3055
author_rank: Super Contributor
timestamp: February 11, 2022, 10:04:09 am
content: Quote from: T_guttata on January 28, 2022, 07:04:05 pmhttps://eleshop.eu/de-ree-de-5000-lcr-meter.html

author: gf
author_rank: Super Contributor
timestamp: February 11, 2022, 10:27:47 am
content: Quote from: T_guttata on January 28, 2022, 12:03:29 pmWhat is the intended operating frequency for the inductor?A real-world inductor is not an ideal inductor, but has various parasitics.So the L you measure at 1kHz may not be representative for its impedance at much higher operating frequencies.

author: mawyatt
author_rank: Super Contributor
timestamp: February 11, 2022, 04:16:44 pm
content: Quote from: T_guttata on February 10, 2022, 09:21:14 pmA simple way to verify the ESR reading is to insert a known small value resistor in series with the capacitor. Make a measurement without the resistor, then with the resistor. Subtract the two ESR readings and this should equal the inserted resistor value, if not you can't trust the LCR meter for an accurate ESR measurement.Best,

author: TimFox
author_rank: Super Contributor
timestamp: February 11, 2022, 05:15:06 pm
content: To "T_guttata":What frequency did you measure the roughly 1000 uF capacitors? Obviously, the reactance decreases with frequency until you approach self-resonance. When the measured reactance is small, the meter will have a hard time resolving the ESR which is less than the reactance.

author: T_guttata
author_rank: Regular Contributor
timestamp: February 13, 2022, 09:34:20 am
content: Quote from: Electro Fan on February 11, 2022, 06:02:32 amThanks, will have a look :-)Quote from: 2N3055 on February 11, 2022, 10:04:09 amThanks. I have ordered a DE-5000 from ebay, was half the price than in this shop. Will arrive in march.Quote from: gf on February 11, 2022, 10:27:47 amI don't know the operating frequencies yet. But I understand that you need 100kHz to measure such small inductances.Quote from: mawyatt on February 11, 2022, 04:16:44 pmI will try that. The ESR value at 100 Hz should not be much different than the DC resistance?Quote from: TimFox on February 11, 2022, 05:15:06 pmI tried all frequencies. The reading was lower than the nominal value at all frequencies.I will return the LCR-300 meter and wait for the DE-5000. Hope I will be satisfied more with the DE-5000.

author: bostonman
author_rank: Super Contributor
timestamp: February 13, 2022, 04:07:50 pm
content: I'm curious, are any LCR meters accurate and correctly measure ESR too?Capacitors have a high tolerance, so value can be off. Then they vary so much in value that a meter with a specific frequency may not show a correct ESR value. The ESR is so small that I don't know how it can accurately be measured anyway.On a side note, I've also seen (and used) those tweezers to measure LCR components while in circuit. I'm uncertain how accurate they are, but I've considered buying a pair due to coming across repair projects where I don't have schematics and the components are 0402 or smaller thus eliminating the possibility of finding a value on the part.

author: TimFox
author_rank: Super Contributor
timestamp: February 13, 2022, 05:39:57 pm
content: I use my DE-5000 to measure ESR of film capacitors to ensure that I have a polypropylene capacitor instead of a polyester capacitor (packaging can be confusing). My good polypropylene capacitors' ESR is low enough to be hard to measure accurately, but the polyester capacitors' higher ESR is usually within manufacturer's specifications.I have some old General Radio standard capacitors, which I have checked against a Wayne-Kerr admittance bridge (at 1592 Hz) and the DE-5000 with excellent results.I have also checked my DE-5000 against series combinations of high-Qcapacitors and low-value resistors as an exercise, and it is generally good for reasonable combinations.