Bias Network for LCR Meter - Page 1
Forum section: electronics / projects

author: mawyatt
author_rank: Super Contributor
timestamp: March 31, 2022, 01:42:34 am
content: Studying the effects of bias voltage on capacitors usually requires an LCR meter with a build-in bias network, or configuring an external network to isolate the DC bias from the LCR meter terminals which has no built-in bias or the LCR bias doesn't have sufficient range.With a brief break in other work we decided to create an external network to support external DC bias with the bench type LCR meters we have and use. After some careful experimenting we found the Tonghui TH2830 to be receptive to AC coupling the High Current and High Potential terminals, our other lab bench meter wasn't tho!!With a relatively large range of potential test capacitors, which includes ceramic, electrolytic, tantalum, and polymer, and a large voltage range we decide to investigate the HP16065A (service manual kindly provided by Thomas) External Voltage Bias Fixture. This provided a baseline schematic and methodology to move forward.Here's our first cut at an external bias fixture to use with a standard bench type LCR meter. The general idea is to insert the fixture between the LCR meter terminals and the actual component testing fixture, wether it be a set of Kelvin clips, tweezers, SMD holder or leaded device fixture/holder. With the standard spacing of the BNC terminals the bias fixture can be directly connect to the LCR terminals with 4 BNC male to male adapters, or with quality BNC cables (either 50 or 75 ohm). The component fixtures attaches to the other side of the bias fixture.In the schematic the LCR High Current and High Potential terminals are isolated with series capacitors. The design is flexible to allow paralleling film type capacitors for greater capacitance, and the Current terminal also supports high capacitance electrolytic types as shown. The LCR terminal are protected with back to back diodes, back to back Zener diodes, and anti-parallel series Zener diodes with a GP diode. Also the Low Potential is protected with triple back to back diodes and shown. These various diode protection schemes are similar to what HP 16065A has, although they may not be required with certain LCR meters (it's always easier to remove or not install a component than add one!!).The DC comes thru a couple resistors (10K and 100K) and a shunt external noise reduction capacitor, Diode D19 is optional to prevent reverse bias if a polarized capacitor is used (C9 and/or C11). A sense line is provided, also with an 10K and 100K resistors and shunt capacitor to allow monitoring the DUT voltage. Unipolar overvoltage monitoring is provided by Zener D17 and an LED, the Zener can be selected based upon the desired voltage range of the fixture, and if bipolar operation is required these should not be installed.Note that the High Current series capacitor(s) are outside the High Potential Sense terminal, which also has series capacitor(s) but is a much higher impedance than the High Current terminal. The general idea is that when a "Short" calibration is performed, the calibration includes the effects of the series capacitors and reduces their measurement effects. A drawback with larger capacitors is the longer time constant to charge the DUT and the fixture capacitors, if one tends to measure larger capacitors, then reducing the 100K charging resistor might be beneficial.One of the reasons for interest in this fixture is to help understand the subtle voltage effects on certain ceramic capacitors, and later polymer and electrolytic types. Note that the PCB is designed for all sorts of variations to allow customization as required.Anyway, thought others might find this useful, we plan on constructing a few types with different components for various voltage ranges and capacitors types.One word ofCAUTION, this hasNOTbeen tested on any LCR meter (yet), and could cause LCR meter damage, so please proceed with care and YMMV!!We'll provide PCB design files and such after we've had time to evaluate the concept and verify the performance. Also likely will design a 3D printed case to hold the PCB.Comments, suggestions, and critique are welcome.Best,

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 01, 2022, 02:42:04 am
content: Hi,HP has 1uF in the Hpot connection and 5.6uF in the Hcur connection:The HP instruments do open and short calibration.I believe the 20 Ohm resistors and the switch are to discharge the DUT. The switch is operated by a safety cover.Jay_Diddy_B

author: jonpaul
author_rank: Super Contributor
timestamp: April 01, 2022, 10:23:40 am
content: Characteristics of capacitors vs bias is well documented since 1960s.Many app notes and papers from HP, Wayne Kerr and old line capacitor manufacturers.We used the HP and WK LCR and bridges with built-in or external bias.Jon

author: mawyatt
author_rank: Super Contributor
timestamp: April 01, 2022, 01:44:25 pm
content: @Jay-D,Yes this is the basis for the design, HP used a 5.6uF series cap in the force line. This limits the lower frequency response and we decided to use a larger effective capacitance by paralleling film capacitors as shown.One could also use a unipolar capacitor like a Al, Ta or Polymer and some experiments show this also works with the Tonghui TH2830 we have, so we included the ability to use. However, we couldn't get the Hioki IM3536 to work with any of the series capacitive techniques, film or otherwise! This LCR meter must have a different type architecture than the TH2830. For our case this isn't an issue since the area where the DC bias measurements are required is in the lower frequency ranges.We just did some more elaborate tests with the TH2830 and having a drive series film capacitance of ~13uF and a sense series cap of 1uF allows reliable measurements of up to ~500uF at 50Hz after a short calibration at the DUT terminals. We setup a test where the DUT was first measured with the IM3536 at 50Hz (and other frequencies) then measured with the TH2830 with the added series capacitors mentioned. We had excellent agreement up to ~1KHz with various capacitor types like ceramic disc, film and electrolytics up to 500uF. The wired setup contributed to errors above 1KHz tho, which should be reduced with a proper fixture.Not sure if all the precaution measures HP took with 16065A are necessary (none were used with the wired setup), but these were included in the PCB since it's easy not to use them!Anyway, the external DC bias technique with the TH2830 seems to work very well!!!Note we included the ability to have a much larger force series capacitance than 5.6uF HP utilized, because we anticipated using the IM3536 which goes down to 4Hz and thus requires a larger capacitance. However after discovering the IM3536 doesn't work properly with this external DC bias technique, the additional capacitance isn't required.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: April 01, 2022, 02:29:06 pm
content: @ Jon,We are aware of the documentation of capacitors vs bias, we even had a full featured materials lab that did very detailed analysis of all sorts of capacitors, dielectrics, materials and such before retiring, and even detailed characterization of highly toxic BeO that was used in theElectrolyticElectrostatic Suspended Gyro (ESG) technology for electrostatic levitation of a Be hollow ball.Our needs are different now, without going into fine details we need the characterize various ceramics, capacitor types (film, disc, MLCC, Polymer, Tantalum, and Electrolytic types) and such for a specific use. Things like capacitance vs bias voltage are only one attribute, others are capacitance vs waveform type, polarity, offset, capacitance relaxation vs waveform period and more, all this is to produce a waveform that has very little added distortion/aberrations from the capacitance. The waveforms are completely arbitrary in shape, amplitude (+-100V), offset, and frequency/period.With the various capacitor types & materials available today, this requires a careful study to understand these characteristics. Hopefully this is all leading to a custom chip design that may employ on and off chip capacitance in a very precise waveform application, where a possible hundreds per chip and total thousand individual precision arbitrary high voltage waveforms are required.As of now we don't know the detailed effects (short and long term) of these waveform aberrations on the system performance, other than it's very sensitive to certain waveform characteristics like a couple millivolts error in a +-100V waveform!!!Best,

author: jonpaul
author_rank: Super Contributor
timestamp: April 01, 2022, 02:46:02 pm
content: Dear MawWatt, Rebonjour, mille mercis, comprends totalement....I can highly recommend the 1980s HP/Yokogawa 4195A network /Spectrum Analyzer 0..500 MHz with the fine impedance test set 41951A and appropriate SMD, TH and binding post adapters.The test set is rated 100 kHz to 500 MHz, with external bias input 0..40V. 4195A has DC bias sweep 0..40VThe voltage rating is very conservative to stay within the 42.2 V SELV classification.The HP 4195A used cost can be ~ 2k plus similar for the test fixtures and adapters.We were very lucky to acquire a mint Analyzer, all test fixtures, adapters and original manuals, from an HP or NITS related in CO.The Zo is expressed in rectangular or polar and easily scalability or storage.We use the set-up since 1992 in characteristics of transformers self capacitance.Bon chance

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: April 01, 2022, 07:16:42 pm
content: Thus my love of the old GR bridges like the 716C. The (separate) detectors are AC coupled and it's easy to bias the DUT to hundreds of volts. Inductance, not so much. For that it might be useful to look at the GR Incremental Inductance Bridge and companion 1308-A high voltage/current audio oscillator to see how they did it.

author: mawyatt
author_rank: Super Contributor
timestamp: April 16, 2022, 02:55:57 pm
content: Update!The custom PCB has been received and now awaiting the components. In the meantime we've been able to get the Hioki IM3536 to work with the external high bias voltage concept shown. The High Sense terminal requires a much higher series protection capacitor, fortunately the PCB allows room for this larger cap and we already have some on order. Also the IM3536 mode of operation and other specifics should allow operation down to 4HzBest,

author: mawyatt
author_rank: Super Contributor
timestamp: April 22, 2022, 09:19:51 pm
content: Components received finally, and we were able to assemble the first bias fixture test PCB this morning. Initial results are very good and everything works as expected! For example, a 0603 test cap measured 4.672pF with the adapter, 4.683pF without on the TH2830, and 4.694pF on the HiokiOf course more tests are in order and will be completed when time permits.Only issue encountered in PCB assembly was we didn't have the 4.7uF film capacitors, so substituted a 10uF for C10. This has a larger footprint with 22mm lead spacing and we had to bend the lends to fit the 15mm spaced holes.The assembled design values for the fixture are R1 and R3 10K, R4 and R2 90K, C1 and C2 (and C10) 10uF 250V film, C3 and C6 0.1uF film, D8,9,10,13,14,15 !N4004, D11,12,16,17 BAV116, D2,3,6,7 18V Zener. D1, D4, D5 not used, and C4,5,11,12,7,8,9 not used.Here's the HV Bias Fixture details. Note that this includes many of the protection features from the old HP which may or may not be required. We've done a number of tests and the HV Bias Adapter works very well with the Tonghui TH2830 and Hioki IM3536.CAUTION:This may cause damage to your LCR meter without proper use and knowledge, if you not familiar with how your LCR meter operates and how the LCR Input protection behaves then you risk potential meter damage. YMMV!!If folks want more detail I'll be happy to provide such.Edit: Schematic updated.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: April 22, 2022, 09:23:06 pm
content: Here's some images of the PCB and setup. We still need to cut the Al extrusion case and drill the end plate holes.Best,

author: free_electron
author_rank: Super Contributor
timestamp: April 22, 2022, 09:51:51 pm
content: cool. here is a schematic for a hioki. at first glance it looks identical to hp's

author: mawyatt
author_rank: Super Contributor
timestamp: April 22, 2022, 10:51:09 pm
content: One of things we were concerned about is when using Kelvin clips. When the clips fingers are open on the low side then the LPot and LCur are not connected together. This might allow a path for a charged cap to attempt to discharge thru the LPot input before the clips makes the complete contact to LCur. Not knowing if this could damage the LPot input is why the back to back diodes D16 and D17 are present which allows a path to the LCur input. Also the diode string of D8-10 and D13-15 allow a current path back to chassis ground which is where the DC bias input is referenced. Since it takes +-2V for the string to conduct they normally don't matter and only provide the path in case the return currents can't get back to chassis easily.We also included the ability to use back to back electrolytic caps for cases where one needs to use high currents at low frequencies. Our IM3536 goes down to 4Hz, so the 20uF film caps look like ~2K there, and you can't pump much current to the DUT without having a large voltage drop across the DC Block. With a couple 1000uF back to back electrolytics then this looks like ~80 ohms and larger AC currents can be supported (see C4,5,11,12, the schematic shows 33uF, that was just for the footprint). The EC jumper allows the electrolytics to be engaged/disengaged when needed and you don't have to suffer the higher leakage under normal use. If you only are concerned about unipolar DC bias then D1 can be included, and you don't need back to back electrolytics, and single one is fine.Anyway, everything seems to work very well!! Just did some quick diode capacitance measurements with reversed and forward biasEdit: Just noted that D4 and D5 should be moved to the DUT side of the DC Blocking Caps on HCur and HPot, schematic updated aboveBest,

author: mawyatt
author_rank: Super Contributor
timestamp: April 24, 2022, 05:03:37 pm
content: Update,We've probably tested well over hundred devices now and can report that we get good agreement with and without the DC Bias Adapter fixture and between the Tonghui TH2830 and Hioki IM3536 LCR meters. Devices ranged with various types of Aluminum Electrolytics from 10uF to 1000uF, Tantalums from 10uF to 100uF, Polymer from 10uF to 1000uF, chips from 4.7pF to 47uF, film types from 1nF to 10uF, and some measurements down to 4Hz (IM3536).No ill effects to report, things work as expected and we get reliable results. We also did some DC measurements with diodes to observe the junction capacitance vs voltage behaviors.When time permits may try and get some software up and running to allow DC sweeps of various components.Anyway, hope this helps some folks that have LCR meters that don't have built-in DC Bias capability, or limited capability, and/or don't have access to the commercial DC Bias add on fixtures which tend to be expensive, even used!!Best,

author: mawyatt
author_rank: Super Contributor
timestamp: May 07, 2022, 07:47:56 pm
content: Latest Update,The LCR Meter Bias Adapter aluminum enclosure has been prepared and assembled along with custom 3D printed end plates. Results are quite promising, even at 1MHz and up to 8MHz, which is limit for Hioki IM3536Here are some images of the assembly and setup with the IM3536 which is directly connected (with support) with 4 BNC adapters, and to the Tonghui TH2830 via 4 BNC cables. The LCR Meter Bias Adapter is compatible with all our fixtures and Kelvin cables (BNC type)Best,

author: mawyatt
author_rank: Super Contributor
timestamp: May 07, 2022, 07:49:45 pm
content: Few more images.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: May 08, 2022, 08:45:24 pm
content: Completed some test comparing various capacitance measurements with and without the Bias Adapter.Here's some capacitance measurements completed on the IM3536 with and without (#) a using SMD fixture at 100KHz.4.6864pf (4.6826pf), 9.9537pf (9.9498pf), 101.043pf (101.039pf), 993.052pf (993.026pf)Even at 1MHz. 4.6726pf (4.6814pf), 9.9385pf (9.9464pf)With a Kelvin Cable at 10KHz.1.00856uf (1.00934uf), 474.80nf (474.81uf), 2.231nf (2.232nf)This gave us some confidence and we made some diode capacitance measurements for SD340 (3a SB), 1N5817 (1a SB), 1N4007 and 1N4148. These were made with Kelvin Cable at 1MHz (per data sheets) using the Bias Adapter to bias the diode under test.Anyway, hope this helps folks that are in need of a DC bias adapter for their LCR meter as the Bias Adapter doesn't seem to degrade the LCR measurement.Best,

author: TimFox
author_rank: Super Contributor
timestamp: May 08, 2022, 10:32:37 pm
content: Have you tried your fixture with a DE-5000 LCR meter?

author: mawyatt
author_rank: Super Contributor
timestamp: May 09, 2022, 12:14:50 am
content: No have not tried it with the DE-5000. Since the chip set in the DE-5000 is based upon a synchronous mod-demod it should work just like with the TH2830 and IM3536.If we had a spare adapter for the DE-5000 I could make a BNC type to DE-5000 adapter and check it out. Also note on the Bias Adapter PCB design, this has separate small HX style 2 pin connectors at the Hcur, Hpot, Lpot and Lcur Meter side I/O, one could use these with a DE-5000 adapter to work with the DE-5000. Suspect the DE-5000 has a lower voltage threshold on the inputs/outputs, so lower voltage protection zeners should be considered.If anyone has a spare DE-5000 connector, will be happy to build up a custom cable and check it out with the Bias Adapter.Edit: One potential issue with the DE-5000 might be during Short calibration, if this requires a DC type galvanic connection between the Hcur and Hpot Inputs then the Bias Adapter won't work because the adapter has a capacitve coupled Hcur and Hpot and won't pass the DC static calibration test. Don't think this DC Short test can be bypassed on the DE-5000 like available on the TH2830 and IM3536 Lab LCR meters.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: May 12, 2022, 04:04:30 pm
content: We've done enough testing using this Bias Adapter with our two LCR meters (IM3536 & TH2830) to consider offering a couple PCBs. The Bias Adapter works quite well indeed, and why we've decided on giving up a couple PCBsAlthough a little slow as the series film caps charge and discharge but gives very accurate results almost entirely dependent upon the LCR meter performance, which is what you want and not limited by the adapter.The Al extruded case with Al end plates provides a very good stable physical and electrical environment and using the "finger test" around the case while measuring a Venkel 1.0pF chip C0G cap at up to 8MHz doesn't affect even at the 1.0009pF level least digit (0.1fF), of course getting a finger within ~75mm of the SMD test fixture where the DUT is held does effect this 0.1fF digit!! So the end DUT test fixture is the limiting factor regarding external influences, not the Bias Adapter, and results don't seem any different than if the DUT fixture was directly attached to the LCR meter terminals.Even works down to 4Hz, and has provisions for adding much larger valued electrolytic capacitors (back to back for bipolar bias use) for situations where large value capacitors need to be measured at very low frequencies.Someone more industrious could "close the loop" with DC bias voltage measurements and reduce the charge time using the LCR and DMM USB or LAN interfaces with some custom developed code. This would be especially beneficial for measuring large capacitors at very low frequency, since the charge time will be long.We have only a couple PCBs to offer those that would like to build up a DC Bias Adapter for their LCR meter (need to keep a couple for ourselves).This is a small gesture in return for all the great help some folks here have provided and a small return to the "community"Please, don't inquire if you don't intend to build the Bias Adapter, as with only a couple PCBs available this takes away from those that do intend to use the PCBs and benefit from such.Anyway, send a PM and SASE if interested in the PCBs.Edit: Added Gerber, Schematic and BOM. Be sure and change Gerber to .zip and BOM to .csv file types. PM for details on building.Best,

author: nmak
author_rank: Newbie
timestamp: September 01, 2022, 07:50:29 am
content: Thank you for sharing your very interesting work.Have you tried it with HP4284A or Keysight's E4980A?Which is the maximum bias voltage of this network?

author: mawyatt
author_rank: Super Contributor
timestamp: September 01, 2022, 01:18:12 pm
content: We only have access to the Tonghui TH2830, Hioki IM3536 Lab type LCR Meters, so this is all we've tested with. However, would think this should work with other Lab type LCR meters unless they have some limitation during Short Calibration (DC cal must be bypassed).The maximum bias voltage would be limited by the coupling capacitors utilized and the protection diodes used. Of course the LCR meters also have a maximum voltage they can accept at the Inputs/Outputs.Best,

author: Smokey
author_rank: Super Contributor
timestamp: November 28, 2023, 08:06:36 am
content: Not sure how I missed this. I'm totally going to build one of these.Thanks!

author: mawyatt
author_rank: Super Contributor
timestamp: November 28, 2023, 02:43:10 pm
content: This works very well with our TH2830 and IM3536 Lab Grade LCR meters, however it does not with the DE-5000, note below.Edit: One potential issue with the DE-5000 might be during Short calibration, if this requires a DC type galvanic connection between the Hcur and Hpot Inputs then the Bias Adapter won't work because the adapter has a capacitve coupled Hcur and Hpot and won't pass the DC static calibration test. Don't think this DC Short test can be bypassed on the DE-5000 like available on the TH2830 and IM3536 Lab LCR meters.Be sure to enclose the PCB in a rigid metal case (as shown), for mechanical and electrical stability. We have no problem with sub picofarad repeatability using the Bias adapter with SMD fixtures.Best,

author: Smokey
author_rank: Super Contributor
timestamp: November 28, 2023, 06:14:26 pm
content: Interesting. I have a MS5308, which from what I understand is the same chipset as the DE5000.Is that issue with calibration something that someone confirmed on an actual unit with your bias fixture or is that still speculation?Assuming the meter does in fact fail calibration because of the short test, what sort of bad things would happen if that cap was just held shorted for that test then opened back up afterwards?

author: mawyatt
author_rank: Super Contributor
timestamp: November 28, 2023, 09:11:55 pm
content: It was tested on our DE-5000, so not speculating.If one could figure out how to bypass the DC short calibration, then suspect it should work fine.Would think you could use the bias fixture without a short calibration, but not sure what effect it would have on the results tho. Also not sure what level of DC bias a DE-5000 can accept, the lab instruments we use have a relative high rating which is what the protection diodes in the DC Bias Fixture are rated for. Since the DE-5000 has effective +-4.5 volt internal rails derived from a 9V battery, would think anything above +-4.5 on the inputs might be a problem and protection diodes should be adjusted accordingly.Don't know anything about the MS5308, so might be worth a try to see if you can bypass the short calibration without a DC short, or if the software has the ability to bypass this like the lab grade instruments do.Best,

author: Smokey
author_rank: Super Contributor
timestamp: November 29, 2023, 12:05:07 am
content: Cool. Thanks for the update. I think I'll give it a shot and see how well it works with the short cal done while the coupling cap is jumped out.I saw your BOM is all from LCSC. What was the approximate BOM cost? I'll probably find Digikey equivalents.

author: mawyatt
author_rank: Super Contributor
timestamp: November 29, 2023, 03:05:46 pm
content: Don't recall the cost, the parts weren't expensive tho. Check the spacing on the BNC, recall they were a few mm off, but was still able to get a good fit by just slightly skewing them when soldering in place. At some point was going to tweak the layout but never got around to it.If one plans on measuring large caps, then consider installing a bypass momentary push button switch with a 1K series R around the 100K R from the DC bias Banana connector. The idea is to push the switch to quickly get the large cap up to voltage for LCR measurements, as otherwise it can take some time for these large caps to stabilize in DC bias. This is something we'll likely do if/when we build another fixture, one dedicated for high value caps with larger series capacitors (PCB has place & jumper for these electrolytics, see schematic) and probably even a momentary discharge switch to discharge the cap before and after testing.Best,

author: Smokey
author_rank: Super Contributor
timestamp: December 05, 2023, 11:54:42 pm
content: I made a Digikey BOM with what I think should be equivalent parts. The total is about $41 in parts, with $20 just in BNC connectors. This is about double what you listed from LCSC, which is sort of what I expected.| ID | Name | Designator | Quantity | MFG | MFG Part Number || 1 | 1N4148 | D4,D5,D8,D9,D10,D13,D14,D15 | 8 | SMC | 1N4148W || 2 | XH-3A_C722863 | HIGHPOT,HIGHCUR,LOWCUR,LOWPOT,BIAS | 5 | | || 3 | 33u | C4,C5,C11,C12 | 4 | Panasonic | ECA-2EM330 || 4 | 10uF | C1,C2 | 2 | Cornell Dubilier | 106MMR100K || 5 | HDR-M-2.54_1x2 | EC | 1 | | || 6 | 100nF | C3,C6 | 2 | Kemet | MMK5104J100J01L16.5TR18 || 7 | C232A475J6SC000 | C7,C8,C9 | 3 | Epcos | B32522C0475J000 || 8 | 1uF | C10 | 1 | Panasonic| ECW-FD2W105Q1|| 9 | 1N4004W | D1 | 1 | SMC | 1N4007FL || 10 | MM1Z10-C128709 | D2,D3,D6,D7 | 4 | Nexperia | PDZ10BGWX || 11 | 1N4148W_C432607 | D11,D12,D16,D17 | 4 | SMC | 1N4148W || 12 | 10k | R1,R3 | 2 | Stackpole | RMCF1206FT10K0 || 13 | 100k | R2,R4 | 2 | Stackpole | RMCF1206FT100K || 14 | Header-Male-2.54_1x3 | TEST | 1 | Adam Tech | PH1-03-UA || 15 | DOSIN-801-0030 | HC,HCUR,HP,HPOT,LC,LCUR,LP,LPOT | 8 | Molex | 731385033 |I actually used the cheaper BNC connectors with plastic housings, RF1-01K-D-00-50-BK-HDW.NOTE1: This was generated from the V4 design. I have not confirmed all these parts yet. Ordered but not yet received or assembled or tested. No guarantees they are actually fully equivalent yet.Note2: Fixed 1uF cap part number. Previously listed 0.1uF.Note3: Items 4 and 7 are either/or stuffing options. Item 3 is qty2 and optional.

author: mawyatt
author_rank: Super Contributor
timestamp: December 06, 2023, 01:18:24 am
content: Typical 2X parts cost from Mouser/DigiKey vs LCSC, however LCSC has a higher shipping charge. The BNCs are somewhat expensive, but we already had/have a bunch as we use these a lot for other projects/tasks, same for most of the "other" parts except the 10uF film types, these we didn't have in stock.You don't need the 33uF if you are using the 10uF film types, and visa vera. The electrolytics are for measuring high cap values (like other electrolytics) at low frequencies, otherwise use the film types, check out the schematic. Also note that if you plan on going to low frequencies (like our Hioki IM3536 can go to down to 4Hz), you may need to make C10 larger than 1uF, we used another 10uF but had to fold the lead underneath to fit the thru-holes.This DC bIas Fixture works a treat for our use, so hopefully you get some good use also!!Now that our main project is heading to a Trade Show 12/7/23 we may have some "free" time to build another with the mentioned switches for fast charge/discharge use with high value DUT caps, and spend more time with the plotting software.Anyway, hopefully works with the chip-set in the MS5308.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: December 08, 2023, 07:54:13 pm
content: We have some work ahead to measure a bunch of large valued electrolytic capacitors, which may include capacitance change over voltage ranges. So the plan was to use this DC Bias Network with our LCR Bench meter, however recalling that one must wait some time before each measurement to allow the DC bias to stabilize (large RC time constants involved), we looked into providing a means to improve this Bias Network.Bypassing resistor R2 in the schematic with a momentary Push Button Switch solves the long delay and allows quicker charging (and discharging) of the DUT. The switch was installed on the side of the aluminum housing as shown.Our procedure when measuring larger valued capacitors with DC bias is to always start with the DC power + lead shorted to the - return lead"At the Power Supply", then install the DUT, then return the + lead to the PS + Terminal and set the DC voltage. With the Bypass Switch installed, use the same procedure and press the Bypass switch and watch the sense DMM voltage to allow charging to proper level. When removing the DUT, we also short the + lead, wait and then remove the DUT (this discharges the DUT). With the Bypass switch, use same procedure and Push to quickly discharge the DUT before removing.BTW, changing R1 to 1K also helps.Anyway, adding the simple Push Button Bypass Switch makes testing/measurement of high valued capacitors with DC bias a little less tiresome!!! We'll create another version of the schematic and PCB someday to reflect this addition, when time permits.Best,

author: scopeman
author_rank: Frequent Contributor
timestamp: December 09, 2023, 03:18:39 am
content: Hello Mike,This looks like a really well done project.On the BNC spacing there seems to be two standards. I ran into this when I was making some adapter PCB's for some meters I own.I have a Wayne Kerr 4230 and a Wayne Kerr 4250 and also a XJW 01 and some fixtures to use with them one like the one you depicted for SMT parts and one for radial/axial parts. They are all 22mm spacing.It seems that the Wayne Kerr is 24mm on the 4250 and 22mm on the 4230 (the 4250 is the older of the two). I believe that the Wayne Kerr 4230 (200KHz capable) was a rebranding of an Asian companies product but at the moment I can't recall which one.I believe that all modern LCR meters use the 22mm spacing. From measurements on your PCB it looks like you have 22.5mm spacing which accounts for the issue you were having.I was able to import the Gerber files into my SprintLayout6.0 program. Correcting the spacing for the BNC connectors will be fun! I guess it would be easier if I had the native PCB file.Again congrats on the nice project.SamW3OHM

author: Smokey
author_rank: Super Contributor
timestamp: December 09, 2023, 07:14:34 am
content: I was playing with the gerbers as well. I'm no KiCad expert but it looks like it will import Gerbers into an active board layout as lines and holes and it will let you move them around.I'm going to end up making the matching fixture board for this LCR meter anyway, so I'm just going to match what you did on your board.

author: mawyatt
author_rank: Super Contributor
timestamp: December 09, 2023, 01:33:26 pm
content: Think the BNC spacing for modern LCR meters is 7/8" or 22.225mm.We've updated the schematic and PCB to reflect moving the BNC to the 22.225mm spacing, adding a charging/discharging switch connector, and to "clean up" a few minor things.The attached Gerber files are for your review, we haven't built this version (yet).Anyway, hope this helps some. Let us know if you decide to build this and how it works.BTW make sure to enclose the entire fixture within a Faraday shield as shown, having a stable and repeatable electrical and mechanical structure is important for good repeatable results. Also, the electrolytics shown (C5,6,11,12) can be arranged in various ways, for unipolar use, or different capacitance values, or voltage ratings, or physical sizes, all depending on one's needs.Edit: Gerber file updated.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: December 11, 2023, 12:43:10 am
content: CAUTION!!!Do not use this fixture with any East Tester meters, seems they all have the front panel BNCs reversed from the decades old BNC configurations from HP, and used by Agilent, Keysight, R&S, Hioki, Tonghui, B&K, GW Instek and others.https://www.eevblog.com/forum/testgear/east-tester-et4510-lcr-meter/Best,

author: mawyatt
author_rank: Super Contributor
timestamp: December 15, 2023, 07:31:27 pm
content: Updated Gerber files for those interested in this DIY adapter/fixture. The OEM ones are indeed expensive!!Best,

author: Smokey
author_rank: Super Contributor
timestamp: January 10, 2024, 03:24:28 am
content: Finally got around to building up the V4 boards (and making a BNC adapter for the MS5308).It sorta works, but I'm seeing some strange behaviors. I got around the short calibration step by bypassing the caps in the HCUR and HPOT lines during that calibration. I need to measure some reference components without any of this other stuff, and then again with the bias fixture to see how much of an effect that has, but there are bigger issues to deal with first.First issue is that if I route the LCUR and LPOT lines through the V4Bias board, the MS5308 refuses to measure anything. If I instead bypass the v4Bias board and hook the LPOT and LCUR directly to the BNCs on the MS5308 breakout then it works fine (with no bias voltage). This is strange, because apart from the protection diodes those lines are straight through connections on the board. I confirmed the diodes are all installed correctly and I can pass a signal with my function generator through that board fine.Second issue is that applying a bias voltage of over a couple volts causes the reading to rise incrementally until it reads overload on the meter. This never settles out to a stable measurement.Does that make any sense what's going on?

author: mawyatt
author_rank: Super Contributor
timestamp: January 10, 2024, 04:05:41 am
content: Interesting, wonder if this has something to do with the bypassing the caps during calibration. We tried using it with the DE-5000 as mentioned but the meter wouldn't pass the short test, so abandoned that LCR meter.However, we have no issues with the Tonghui TH2830 and Hioki IM3536 using this DC Bias adapter since you can bypass the DC short calibration, and we use the adapter often. We've used the DC Adapter with 60 volts DC bias without issue with mentioned Lab type LCR meters.Also we don't see any significant change is measurements with or without the adapter (with proper calibration) as previously mentioned. For example here's a few measurements from early 2022 comparing the same DUT with and (without) the DC Bias Adapter using the TH2830.4.6872pF (4.6830pF) C0G993.498pF (993.468pF) C0G101.654uF 0.706 ohm (101.783,0.691) Tant21.319uf, 1.43 ohm (21.359,1.42) Tant46.981uF, 0.793 ohm (47.007,0.748) TantMaybe if you can locate another Lab LCR meter, give that a try.If you want to ship to us (with return shipping), we'll test the adapter with our Lab LCR meters.Best,

author: Smokey
author_rank: Super Contributor
timestamp: January 10, 2024, 04:15:33 am
content: Thanks for the reply. I didn't mean to say there is anything wrong with the adapter. It's most likely either a quirk of the front end of the MS5308 (which is based on the same chipset as the DE-5000) or something else I'm doing with the setup.If I get motivated I'll take apart the meter and try to trace out the front end schematic and see what I can see.The strange thing is that with no bias voltage, and the LPOT and LCUR lines connected directly to the meter, it actually looks like it's doing a good job of making a stable measurement across multiple ranges and frequencies, all through the bias fixture caps.

author: KungFuJosh
author_rank: Super Contributor
timestamp: November 04, 2024, 02:04:32 pm
content: Is version 5A the latest? Do you have a BOM and schematic for that version also?Thanks,Josh

author: mawyatt
author_rank: Super Contributor
timestamp: November 05, 2024, 03:17:15 am
content: Quote from: KungFuJosh on November 04, 2024, 02:04:32 pmThere's a 5B and 6A versions now. The 5B version has the ability to select the large Film or Electrolytic coupling capacitors, also the bypass switch connector to speed up charging large value capacitors. The 6A version is tailored for higher frequency use than 5B and doesn't have the electrolytic selection option, but also has the bypass switch connector.Here's the Gerber and Schematic files, along with images of the assembled 6A version and PCBs for 5B and 6A. Note we had to use two 2.2uF Film caps paralleled for C2 since we didn't have a 4.7uF in house.Study the schematics to get an idea of how these DC Bias Adapters works (distilled from old HP fixture and Hioki reference), basically providing DC Isolation by means of series coupling capacitors in the Hcur stimulus line and another in the Hpot measurement line. There's no need for DC Isolation on Lcur or Lpot as they are normally around ground potential even with applied External DC Bias.The optional protection Diodes and Zeners add a layer of protection for the LCR Meter, some modern quality Lab LCR Meters have built-in protection, +-42VDC is common, however these optional components provide some added meter protection.Edit: Updated Schematic for 6AAlso, none of the component values are critical nor needs to be matched, just about any good quality, stable components should work. For the V6A pay attention to the Coupling Capacitors ESRand ESL, here is where the quality 0.1uF C0G helps!Best,

author: mawyatt
author_rank: Super Contributor
timestamp: November 05, 2024, 01:31:18 pm
content: Note updated with corrected schematic V6A, see above.A little more detail on the workings of these adapters. In V5B the CHG-SWT 2 pin connector is for a Push Button Momentary Contact Switch, in V6A this SWITCH 3 pin connector allows a Charge and Discharge capability depending on the Switch type (3 position momentary vs 2 position momentary).C1 and C2 selection are based upon desired maximum DC Bias Voltage, Low Frequency Range, Highest DUT Capacitance Range and type LCR Meter used. We've found with our intended usage and available LCR Meters (TH2830 & IM3526) that C2 is ~ 1/2 of C1 value works. We used 10uF 100VDC for C1 as this was available and had to parallel two 2.2uF 100VDC Capacitors (~4.4uF) for C2. The IM3536 is more sensitive to C2's value than the TH2830 which works fine with C2 as 1uF. Suggest trying different values for C1 and C2 your intended LCR Meter use and component range.C8 and C13 are for 0.1uF C0G types with low ESR and ESL (these act as "bypasses" at higher frequency), C5 and C10 allow additional paralleling with C8 and C13 which we didn't find necessary and omitted.The reason for the long resistor strings from the BIAS Connector is to decrease the effective capacitance "seen" from the DUT HC BNC connector, and also decreases the voltage across a single resistor, which is likely overkill unless one envisions very high voltage use.One very important consideration is the shielding and mechanical stability of the PCB enclosure. Use a sturdy metal enclosure (we used an extruded Aluminum section as shown in the images) with good all around shielding connected to the BNC ground and you will be rewarded with highly repeatable results that agree quite well with measurements obtained directly from the LCR Meter, we know we've confirmed this multiple times at pF levelsAnyway, we have a couple extra PCB sets, PM if interested.Edit: As a sanity check we compared some results {with} and without the V6A Bias Fixture @ 1MHz on the IM3536 at ~26.6C ~44% RH.One interesting note is from a measurement over 2 years ago with a 10pF Mica & 10nF Polystyrene*.1nF Polystyrene 998.125pF {999.756pF}1nF Mica 1.00688nF {1.00808nF}10nF Mica 9.99980nF {10.0707nF}2pF Mica 1.9762pF {1.9766pF}10pF Mica* 9.9304pF* {9.9247pF}10nF Polystyrene* 10.3343nF 93.96mΩ* {10.3252nF 98.15mΩ}* Measurement result without Bias Fixture from over 2 years ago!Best

author: bryans
author_rank: Newbie
timestamp: May 01, 2025, 01:52:10 am
content: Hey there Mike,Just joined the forum specifically because of your your DC Bias project as I stumbled upon it via Google. Is 5B the most current version (for lower frequency usage) of your bias adapter? It's a killer solution to being able to sweep test power supply chokes on my BK 891. I'd like to build my own asap.Can you also let us know where you obtained the aluminum extrusion for your case? Very simple solution to shielding.Thanks!

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 01, 2025, 04:24:15 am
content: bryans,The solution that was shared by Mike is for testing capacitors with a DC bias voltage. If you are interested in testing inductors you need a different kind of bias circuit.I shared an alternative method, not using an LCR meter, in this thread:https://www.eevblog.com/forum/projects/inductor-saturation-tester-alternative-route-to-dump-the-excess-energy/msg183197/#msg183197This circuit will allow you to observe inductor saturation.Regards,Jay_Diddy_B

author: mawyatt
author_rank: Super Contributor
timestamp: May 01, 2025, 06:18:44 pm
content: As Jay mentioned ours is a DC Voltage Bias Adapter, not intended for higher currents for DUTs. We used this for DUT capacitors and semiconductors in reverse bias.The Extruded Al cases are from AliX, you can find all sorts of these type cases there, we have a few different sizes laying around. The one we used was 130mm long and cut in half.Best

author: kam
author_rank: Newbie
timestamp: May 06, 2025, 02:06:25 am
content: HI Mike,Thank you for the amazing works and sharing themI am trying to make one from your files.I found your 5A Gerber files from the previous post, but the ver5B that you shared in below post has a SMA like fixture? Did I miss the 5B version?Quote from: mawyatt on November 05, 2024, 03:17:15 am

author: mawyatt
author_rank: Super Contributor
timestamp: May 06, 2025, 03:33:21 pm
content: Quote from: kam on May 06, 2025, 02:06:25 amThere's no SMA version, all versions use BNC connectors to be compatible with typical LCR Meters and Fixtures.Best

author: kam
author_rank: Newbie
timestamp: May 06, 2025, 05:14:10 pm
content: Hi Mike,This is what I see in your Version 5 Gerber file. It looks different than the picture you shared. I was just wondering if there is a different file somewhere for the 5B version...Kind Regards,Kam

author: kam
author_rank: Newbie
timestamp: May 06, 2025, 05:56:17 pm
content: I was making the current bias fixture for the LCR meter and noticed that the BK precision 880 has a a little breakout board under the terminals, it looks alike the protection circuit ....

author: mawyatt
author_rank: Super Contributor
timestamp: May 06, 2025, 06:59:49 pm
content: Quote from: kam on May 06, 2025, 05:14:10 pmThat's an earlier file for the Direct Connect LCR Fixture for SMD devices.https://www.eevblog.com/forum/projects/different-type-lcr-smd-fixture/msg5061028/#msg5061028https://www.eevblog.com/forum/projects/custom-adapter-collection/msg5809155/#msg5809155Best

author: mawyatt
author_rank: Super Contributor
timestamp: May 06, 2025, 07:03:37 pm
content: Quote from: kam on May 06, 2025, 05:56:17 pmMake sure you can do a Short Calibration with this BK Meter, some require a DC connection between terminals for the Short Cal to work. The DE-5000 will not perform a Short Cal. with the DC Bias Fixture, altho Open is no problem.Best

author: kam
author_rank: Newbie
timestamp: May 06, 2025, 07:41:38 pm
content: Hey Mike,I think you posted the incorrect file in the 5B verison post attachmentI uploaded it to JLCPCB, and only see that surface mount board. May you kindly share the 5B files againThank you for the tips on the BK meter!Thanks for sharing. I like your designand learned from you of putting the different values of block caps in parallel to allow the signal pass through from low to high frequency! NICE!!!!!Thanks once again!Kind Regards,KamQuote from: mawyatt on November 05, 2024, 03:17:15 am

author: mawyatt
author_rank: Super Contributor
timestamp: May 06, 2025, 08:56:12 pm
content: Quote from: kam on May 06, 2025, 07:41:38 pmHere's the latest of what we have, V5B and V6A. Version 6A is the High Frequency Version, which doesn't have the ability to host the large valued Electrolytic Caps on the PCB that V5B does, however the V6A layout is optimized for Higher Frequency use. Both are the same Form Factors.If you build the 5B version be sure to include the Bypass Switch capability, this really helps with the Long DC Bias Time Constant of Large Electrolytic and Polymer Caps.Also check out our DC Bias Sweep Software we implemented for doing DC Bias Sweeps. Very crude (our software skills are limited) but sufficient for our simple needs.https://www.eevblog.com/forum/testgear/lcr-meter-plot-software/Best

author: kam
author_rank: Newbie
timestamp: May 06, 2025, 11:22:01 pm
content: Thanks a TON, Mike <3Well received and noted on the switch!I was wondering, can I use it up to 400V assuming the blocking cap rating are high enough?I am new to the electronics and learning about different type of dielectric material. I wanted to be able to test the Electrolytic cap on the PFC output if that is possible ...I will share some picture and try the program when the parts are hereThanks a lot of sharing your knowledge and work/efforts ...Kind Regards,Kam

author: mawyatt
author_rank: Super Contributor
timestamp: May 07, 2025, 12:43:23 am
content: We've never tried anything over ~100VDC and very careful not to induce a quick charge or discharge into/from the LCR Meter terminals. The potential damaging energy from the capacitor is proportional to CV^2, so HV can store considerable energy in a small valued capacitor.Of course you'll need proper rated capacitors in the fixture to handle this HV level, and you'll be venturing into new territory, so be very careful as 400V can be damaging and lethal.Best

author: aronake
author_rank: Frequent Contributor
timestamp: July 21, 2025, 02:41:39 pm
content: Awesome project! I have a Tonghui TH2830 and has been looking into how to arrange DC biasing to test MLCCs. So just got boards ordered.

author: mawyatt
author_rank: Super Contributor
timestamp: July 22, 2025, 07:23:32 pm
content: Thanks, be sure and check out these if you are involved with SMD components and bench LCR Meters like your TH2830.https://www.eevblog.com/forum/projects/different-type-lcr-smd-fixture/https://www.eevblog.com/forum/testgear/lcr-meter-plot-software/msg5861983/#msg5861983https://www.eevblog.com/forum/metrology/lcr-meter-tests/Best

author: mawyatt
author_rank: Super Contributor
timestamp: July 22, 2025, 07:57:38 pm
content: Here's modification we did awhile back with one of our cheap AliX SMD LCR Meter Fixtures. This basically AC couples the High Force and Sense terminals with some protection diodes and resistors for the DC Bias input with some decoupling. We may have published this before but can't remember!!Best

author: aronake
author_rank: Frequent Contributor
timestamp: August 02, 2025, 06:15:04 pm
content: Im almost done with my build now.Some questions:J2 seems to add extra capacitance by adding jumpers. What is the rule of thumb on how big capacitance should be used vs DUT capacitance?C7 and C8 are an alternative to C1 and C2 or all should be used? C7 and C8 would then be on the back of the PCB.My understanding is that either C11 220uf polymer or C15 1500uf electrolyte should be used, is this correct? C11 is only double the capacitance of C4 and C5 in series. It seems then using something bigger in C11 or use C15 would be the better option, or?How are measurements affected with too little capacitance? I would think results would be low measurements as the LCR meter would measure the capactiance in the DC bias network rather than DUT, or something like that.

author: mawyatt
author_rank: Super Contributor
timestamp: August 02, 2025, 06:46:23 pm
content: What version are you referring too?Generally you want the added series capacitance to be larger than the DUT capacitance, this way the DUT voltage is higher. Larger capacitors have a higher Effective Series Inductance (ESL) which limits their high frequency performance, whereas smaller capacitors like SMD capacitors have less ESL and perform better at higher frequencies. Paralleling both allows better overall performance over a broader frequency range.Best

author: coppercone2
author_rank: Super Contributor
timestamp: August 02, 2025, 06:49:30 pm
content: it looks like you have the same problem as me with excessive wicking on the copper binding the grounds together. It ends up being disapointing because you thought it would be flexible but it is stiff and prone to breaking.I still need to do experiments with using hemostats or yellow orche as solder flow blockBraid-wicking makes alot of DIY project ideas turn into trash :'(I remember a long time ago I thought I could make this sick RF gasket out of braid and of course it got thrown into the trash

author: mawyatt
author_rank: Super Contributor
timestamp: August 02, 2025, 07:01:52 pm
content: ^^^^This must be the wrong thread??Best

author: coppercone2
author_rank: Super Contributor
timestamp: August 02, 2025, 07:02:23 pm
content: the wires on the BNC connectorsfrom the left #1 looks mildly flexible in the middle and #2 and #3 looks like they wicked solder all the way throughI did a big project with ALOT of ground connected banana connectors recently and they all got fully connected by a solder bridge, which makes replacement annyoing. I tried my best to get at least 1/4 inch of flexible copper in the middle between the binding posts (separated by ~1 inch) for a panel but it was a failure, I might as well have used solid copper strap instead of braid.Its also a very annoying problem for some battery holders that need jumpers, because you see that it very clearly flexes alot upon each battery insertion and its tremendously hard to get a 'soft' copper jumper between battery holders that might be like 3/8 inch apart. To have it remain flexible you need a big 'service loop' that makes it look like crap and ruins the compactness of it.yellow is marginal red is flawedWhen I had my panels in mind I imagined you can desolder the center pin, unscrew the nut and then replace the connector without resoldering the electrical washer. Bending solder infiltrated wire is precarious at best.I also wondered about putting some 'blocker' crimp like the little 'ferrules' that you use for bead binding arts and crafts to restrict the flow of solder. Its like a gigantic annoyance for long daisy chains that get infiltrated by solder. Ends up being way more work to do a simple mod or repair. Also when this happens it sometimes totally destroys the idea of separating the front panel from the instrument without desoldering for getting quick access, if its built this way.

author: mawyatt
author_rank: Super Contributor
timestamp: August 02, 2025, 07:17:27 pm
content: Those ground wires are fine. They help ground the 4 LCR BNCs, which is redundant as the BNCs are securely grounded by the metal case (paint removed under the washers). Guess if you wiggled these wire back and forth they would break, but they were soldered after the BNC were secured and tightened, so no issues!!The fixture works very well for evaluating SMD components, no coaxial cables/connectors required other than for the DC Bias source and DMM banana cables.Edit: BTW there were the ground wires that came with the fixture as supplied, they were tinned type twisted as shown, so no solder wicking!!Best

author: coppercone2
author_rank: Super Contributor
timestamp: August 02, 2025, 07:22:32 pm
content: I have zero things to say about the electrical properties, I just mean its a somewhat unsolved nusence with the mechanical problems resulting from solder flow. I hope to practically kill this problem one day, and perhaps send it back in time to 1960. I wasted alot of time having wires from the front panel break off at the end of a repair that required some serious effort to fix, sometimes when I look at old equipment I just think to save myself the trouble and carefully rewire every single wire on the FP at the end of repair.try neatly and robustly jumpering these fucking things, which flex like 1/8 of an inch on battery insertionhttps://www.newark.com/productimages/large/en_US/4573576.jpg

author: mawyatt
author_rank: Super Contributor
timestamp: August 02, 2025, 07:45:25 pm
content: See note we added above. These ground wires came with the fixture and were twisted pre tinned type.Yeah we've experienced wicked solder going up thin stranded wires that broke inside the insulation and became intermittent. Those were a PITA to find!!!BTW one may wonder why we didn't add any protection diodes on the Lc and Lp BNCs on the right. The reasoning was they weren't necessary with our bench type LCR Meters (TH2830 and IM3536), these already have good input protection on the low side (good on high side as well). We were/are more concerned for the high side Hc and Hp inputs so added the diodes there to keep the inputs well within +-42V per meter specs. Also since this fixture is dedicated for just small SMD components, those won't hold significant energy storage like a large leaded or physically large components which could be used with the other DC Bias Adapter with Kelvin Clips or other cable connections and why it has diode protection on both ends!!Best

author: aronake
author_rank: Frequent Contributor
timestamp: August 03, 2025, 07:19:52 am
content: Quote from: mawyatt on August 02, 2025, 06:46:23 pmThanks!What are your thoughts in impact of leakage current of capacitors? I could see that leakage from the bias voltage may even destroy the LCR meter. Or not too much concern? Or other ways leakage current would impact the measurement?I see in the schematic that the DUT capacitor is charged with postive voltage thought the High current connector. How is negative reaching the capacitor? Is any of the connectors in LCR meters connected to ground so negative goes this way? I could think that negative current on LCR meter is connected directly to ground.

author: mawyatt
author_rank: Super Contributor
timestamp: August 03, 2025, 12:56:26 pm
content: Quote from: aronake on August 03, 2025, 07:19:52 amLeakage shouldn't be a problem, the protection diodes limit the voltage the LCR Meter terminal "see". Our two LCR Meters have a +-42VDC Input limit, and the fixture diodes limit well before this.Caution:The EastTester LCR Meters have the Low (Lc and Lp) and High (Hc and Hp) BNC connectors reversed from what every OEM does that we've seen or used. The DC Bias Fixture Layout must be flipped horizontal if using an ET brand LCR Meter, otherwise you may damage the meter and for sure won't achieve reliable measurements.What LCR meter are you using?Best

author: aronake
author_rank: Frequent Contributor
timestamp: August 03, 2025, 02:04:05 pm
content: Quote from: mawyatt on August 03, 2025, 12:56:26 pmI have a Tonghui th2830.On leakage, great! good to know. I may add a sizable polymer capacitor then for the "highest capacitance range"

author: amar87
author_rank: Regular Contributor
timestamp: August 28, 2025, 07:21:49 pm
content: I would like to share my implementation of Mike's bias voltage network. I have a fetish for these hammond cases so i really wanted to make it fit in one of them. I also like the safety banana plug types. So i wanted to use them.

author: mawyatt
author_rank: Super Contributor
timestamp: August 29, 2025, 12:52:30 pm
content: That looks great, well doneWhat type of Hammond case are you using?Best

author: amar87
author_rank: Regular Contributor
timestamp: August 29, 2025, 06:12:48 pm
content: 1455L801 you can also get it in black, and the plastic frames can also be in different colors(i think), front panels are out of pcbs.

author: amar87
author_rank: Regular Contributor
timestamp: August 29, 2025, 06:20:03 pm
content: I would like to share the Altium and the solidworks files but i have no idea if the forum will accept such big files.