ESR meters with high resolution - Page 1
Forum section: electronics / projects

author: tigr
author_rank: Regular Contributor
timestamp: September 03, 2017, 10:03:25 am
content: On the Internet, there are many schemes of ESR meters with different accuracy and resolution. There is an opinion that the ESR meter does not need high accuracy and resolution. But time passes, everything changes. Modern s are difficult to measure with simple probes and testers. Among the s removed from the boards there is also many high-quality s, suitable for further use.To do this, more accurate meters are needed.ESR meter with high resolution0,0001Ohm.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: September 03, 2017, 10:38:48 am
content: hmmm i cant read the Cyrillic, but something tells me it look similar to Jdiddy's ESR adapter here --https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/left side = logic square generator, right side = op amp reads left over voltage?

author: tigr
author_rank: Regular Contributor
timestamp: September 03, 2017, 11:34:14 am
content: http://people.overclockers.ru/TerAbit/13666/MODERNIZIROVANNYJ_CIFROVOJ_IZMERITEL_ESR_S_POVYShENNOJ_RAZREShAYuSchEJ_SPOSOBNOST_Yu_0_0001_OM/

author: tigr
author_rank: Regular Contributor
timestamp: September 03, 2017, 06:00:45 pm
content: Quote from: 3roomlab on September 03, 2017, 10:38:48 amI did not see the technical characteristics and the table of measurement results."left side = logic square generator, right side = op amp reads left over voltage?"The compensating voltage from the trimmer R4 through R30 is applied to the non-inverting input. DA3.DA3 amplifies the useful signal 5 times, forming a less sensitive measurement subband.

author: ocw
author_rank: Regular Contributor
timestamp: September 03, 2017, 06:04:05 pm
content: QuoteWhat is the accuracy of this 0.1 milliohm digit of resistance? It is easy to get all sorts of extra digits of resolution these days. However, it doesn't mean that much if you have 0.0001 ohm resolution on a meter that has 2% accuracy compared to 1 ohm "full scale" +/-20 least significant digit.When is a 0.1 milliohm difference is resistance importantfor youand why is that difference significant? Sometimes better numbers are meaningless. I can get attoamp and even zeptoamp resolution on my ADA4530-1 current to voltage converter. Unfortunately the lower numbers are not that meaningful or accurate. It becomes accurate for 1 femtoamp and above readings.For myself, the ESR of blocking capacitors is important for RF amplifiers in the 500 MHz region. A 1 ohm ESR will have 7 watts dissipation on the small SMD capacitor due to the 2.65 amps of 500 MHz RF passing through it. I use a Array Solutions AIMuhf analyzer for a relatively low cost way of comparing the ESR of the 1000 pF capacitors at that frequency. A special tweezer probe and calibration is required. Below is a comparison of the ESR at 100 and 500 MHz of some 1000 pF SMD capacitors which I have currently available. The 100 MHz data is fairly reliable while the 500 MHz figures are more likely to be affected by measurement probe limitations.100 MHz 500 MHzPart Number Ohms ESR Ohms ESR MFGR Voltage Ceramic Dielectric500R15W102KV4T 0.006 0.743 Johanson 50V X7R101R15W102KV4T 0.006 0.863 Johanson 100V X7R500R15N102JV4T 0.005 0.869 Johanson 50V C0GC0805C102J5GACTU 0.005 0.927 Kemet 50V C0GGRM188R71H102KA01D0.0750.934 Murata 50V X7RC1210C102JDGACTU 0.007 1.646 Kemet 1,000V C0GCL31C102JBCNNNC 0.005 2.739 Samsung 50V C0GMC22FA202J-F 0.0054.692CDE 100VMICA [2000 pF]Unfortunately, the capacitors need to be rated at least 200 volts, so only one of the above is appropriate for my use.For capacitor testing at 10 and 100 kHz, my mentioned AIMuhf measurements come close to those obtained from my Extech LCR200 meter.

author: tigr
author_rank: Regular Contributor
timestamp: September 03, 2017, 06:36:47 pm
content: Quote from: ocw on September 03, 2017, 06:04:05 pmThis is something that can be achieved. As the world record for high jump.Thanks for the info.

author: ocw
author_rank: Regular Contributor
timestamp: September 03, 2017, 07:49:41 pm
content: QuoteI guess that I was happy to talk about zeptoamps even though it didn't mean much...I added one 1000 pF capacitor to my data collection message and added similar ESR figures for 100 MHz. Those measurements are less likely to be corrupted by my SMD test cable. I changed the 500 MHz ESR figure for my 1,000 volt capacitor. I must have had a bad connection to it the first time.

author: tigr
author_rank: Regular Contributor
timestamp: September 03, 2017, 08:11:50 pm
content: I, too. Although such frequencies are not available to me. My tasks are much easier than yours.This is the only amateur radio scheme of the meter ESR up to 20 MHz, which I saw.

author: MasterT
author_rank: Frequent Contributor
timestamp: September 03, 2017, 09:50:59 pm
content: A radio, an SDR, comes to my mind when I see a drawings. You can buy Si4432 this days, $3 on aliexpress, and measure in 240-960 MHz range w/o building /constructing your own board. Two units, one transmitter and another receiver, with 100 something dB dynamic range. Same approach would works for lower frequency end, Si4735 can measure from 153 kHz, and oscillator at this frequency quite easy to build

author: ocw
author_rank: Regular Contributor
timestamp: September 03, 2017, 10:02:11 pm
content: I recently received two 100 MHz RF PA's to repair. One might need to have its MOSFET replaced. The other is beyond hope.A picture of the DOA PA is attached. Each PA board is rated at 350 watts. Many of those are combined to produce 44 kW output. While C14 at the upper right is not a DC blocking capacitor, the two are the same size and value. There is a little more than that wrong with the damaged board.

author: tigr
author_rank: Regular Contributor
timestamp: September 03, 2017, 11:09:41 pm
content: Test probes.On them depends largely on the result of measurements. They must make a minimum error.

author: dave_k
author_rank: Frequent Contributor
timestamp: September 03, 2017, 11:22:39 pm
content: Quote from: ocw on September 03, 2017, 10:02:11 pmWow!Any information as to the cause of this flamy death? Lightning?

author: ocw
author_rank: Regular Contributor
timestamp: September 03, 2017, 11:40:49 pm
content: QuoteLightning is the usual cause for the RF PA failures. However, that one had abnormal symptoms--it didn't have the usual melted trace on the RF combiner board caused by lightning. After the initial problem, the damaged area had enough leakage current to fool the transmitter's fault detection circuit. That caused the board to bake with about 110 watts of dissipation on just that board continually for about four months before the problem was noticed. It is unknown how much additional damage was caused by that heat after the initial fault.

author: tigr
author_rank: Regular Contributor
timestamp: September 03, 2017, 11:49:10 pm
content: Quote from: ocw on September 03, 2017, 06:04:05 pmI sometimes need to know the exact resistance of the resistors.

author: ocw
author_rank: Regular Contributor
timestamp: September 04, 2017, 12:37:41 am
content: QuoteYou always only know the approximate resistance. The approximation magnitude may change, but extra resolution doesn't insure greater accuracy. You might just have greater resolution of an inaccurate reading. If low resistance or ESR measurement accuracy is desired, having a meter which uses Kelvin probes is essential. The resistance of your Kelvin clips and wires won't have a significant influence on your reading.

author: tigr
author_rank: Regular Contributor
timestamp: September 04, 2017, 05:51:24 pm
content: Quote from: ocw on September 04, 2017, 12:37:41 amYes. Therefore, for measurements in the circuit, I use Japanese clips. They are on the right.

author: tigr
author_rank: Regular Contributor
timestamp: September 05, 2017, 07:37:04 pm
content: ESR meter.0,001-10Ohm.

author: ocw
author_rank: Regular Contributor
timestamp: September 05, 2017, 08:41:40 pm
content: QuoteThe schematic diagram doesn't show four points for connection of the four wire Kelvin leads needed for accurate low resistance/ESR measurements.

author: tigr
author_rank: Regular Contributor
timestamp: September 05, 2017, 09:07:54 pm
content: There's a four-wire measurement circuit.