hybridfree/eevblog-posts huggingface dataset:
High Speed Transimpedance Amplifier - Parameters Measurement - Page 1
Forum section: electronics / projects

author: arivalagan13
author_rank: Contributor
timestamp: July 14, 2019, 11:04:14 am
content: Hi allI'm designing a transimpedance amplifier for my thesis work and the same will be implemented in one of the labs for chemical identification.I need to measure the performance of the transimpedance amplifier...I've designed a TIA with OPA656 as a trial...and I have fabricated one with 1GOhm feedback resistance or transimpedance gain.Now, I've to measure the performance of the TIA. I just want to know what are the standard performance measurements that I should take with the transimpedance amplifier.Being a first timer with precision measurements I request the community to give suggestions also about the laboratory equipment needed to carry out the measurements. Because I don't have any measurement facility apart from a 70MHz DSO at my lab. I need to go to a central measurement facility to carry out these measurements.Of particular, I've got a question regarding the current source requirement of the TIA..How do I insert micro and nano current sources to the amplifier? Also, if current sources are available, say, my design requires to measure high-frequency currents...how do I emulate high-frequency current sources in the laboratory? Kindly provide answers and documentation wherever possible.RegardsM ArivalaganResearch ScholarAnna UniversityChennaiIndia
High Speed USB bridge using Arduino Due - Page 1
Forum section: electronics / projects

author: moffy
author_rank: Super Contributor
timestamp: August 20, 2018, 12:44:48 am
content: I have been looking for an easy high speed USB bridge for a while when I ran across this post:https://forum.arduino.cc/index.php?topic=379897.0Anyway I tried some slightly modified code and got: 5.1Mbytes/s using a 256 byte buffer and 8.5Mbytes/s using a 512 byte buffer. It uses the native USB port of the DUE, and is the easisest high speed USB bridge I have come across.So this is just in case you haven't heard of it before. Attached is also my code.

author: moffy
author_rank: Super Contributor
timestamp: August 21, 2018, 12:18:53 am
content: I was wondering if other people would like to share their high speed USB to PC solutions with code? It would be a useful resource.

author: Rerouter
author_rank: Super Contributor
timestamp: August 21, 2018, 08:35:17 am
content: For the sam3x8e (arduino due), the default arduino code driving the USB communications is the main limitation on the native port,https://www.pjrc.com/teensy/benchmark_usb_serial_receive.htmlWhile I was researching for my own project in the past I found many implementations able to handle SD card - Native USB at up to 20MBps, but I never got to programming up that project.as you are saying you want it to act as a "USB Bridge" you should be aware only 1 of the USB ports is native, the other is relying on a UART-USB chip, he will be your main limitation.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 22, 2018, 04:34:01 am
content: Are you looking to get data into the PC or out of it? There's already an open source logic analyzer based on the FX2 and there's apparently a digital out version of the fl2k chip.

author: moffy
author_rank: Super Contributor
timestamp: August 23, 2018, 12:04:23 am
content: I am looking primarily to get data into the PC but bidirectional would be a benefit.I will look into the fx2 logic analysers.
High Speed USB Reliability over Samtec connectors - Page 1
Forum section: electronics / projects

author: tom66
author_rank: Super Contributor
timestamp: March 21, 2023, 01:48:29 pm
content: We are encountering an odd reliability issue with USB in a product. When the issue occurs, the USB will not initialise on our processor. The processor can see the VBUS but the ULPI chip does not function (this is on a Xilinx Zynq, with embedded ChipIdea controller, but external USB PHY).We have a product which has a Samtec BSH/BTH connector stack, which passes USB2.0 (480Mbit/s "High Speed") to another PCB. Then we have a Samtec LSHM connector which mates this across to an IO PCB with a USB connector on it.All traces are 90 ohm differentially routed on dedicated signal layers with a continuous ground plane below them. The connectors aren't 90 ohm rated specifically but it's my understanding for short lengths at our data rates this shouldn't make much of a difference.We have noticed that the USB connectivity issues are resolved on the majority of these units with some flux off (specifically Fluxclene FLU) applied to the connectors with liberal brushing. The boards are washed by our assembly house, but my suspicion is that some kind of oxidation or contamination gets into them at a later stage or the connection is marginal enough that this contamination breaks some boards.Has anyone found signal integrity issues to improve with brand new connectors, when the connectors are cleaned manually? Are there some other things we should be looking out for?Thanks
High stability shunt resistor - Page 1
Forum section: electronics / projects

author: ivonenand
author_rank: Contributor
timestamp: October 31, 2016, 07:03:13 am
content: Hi Guys,I'm doing a modular electronic load design and I need help with choosing a good shunt resistor. I need the shunt to handle 10A and I would like to have at least 100mV of sensing voltage, so that makes a 0.01 Ohm resistor. The module would be quite small and the heatsink would only need to dissipate 50W max, but still the PCB will heat up. So I'm looking for a high temperature stability resistors. The best ones I can find in Mouser of Farnell are 3W SMD are 50ppm/C, which seems quite high, as I'll be using a reference voltage that has 8ppm/C. Anyone has any recommendations?Regards,Ivo

author: bktemp
author_rank: Super Contributor
timestamp: October 31, 2016, 07:11:54 am
content: Vishay/powertron has some nice current shunt resistors down to 1ppm/°C, but they are not small:http://www.vishaypg.com/powertron/SPR 4-T220 seems to be the smallest one suitable for your requirements.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 31, 2016, 01:56:21 pm
content: Yeah Vishay Foil Products Division is the way to go, but you're going to pay for it, too.Tim

author: bktemp
author_rank: Super Contributor
timestamp: October 31, 2016, 03:03:01 pm
content: Quote from: T3sl4co1l on October 31, 2016, 01:56:21 pmYes, they are really expensive, but worth the money, because you get what you pay for.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: October 31, 2016, 03:03:40 pm
content: TT Electronics OARS seriesmight meet your needs at 20 ppm/°C. Far cheaper than those Vishays, in any case.

author: bktemp
author_rank: Super Contributor
timestamp: October 31, 2016, 03:15:51 pm
content: Quote from: RobK_NL on October 31, 2016, 03:03:40 pmThe specified 20ppm/°C is misleading. It says "Element TCR ±20ppm/°C" So the total TCR isn't 20ppm/°C, especially for the lower values. Further down in the datasheet it guarantees only 40ppm/°C.I have used the older OAR through hole version, and it is really bad. Maybe it is a problem with the stand-off affecting the temperature coefficient, but I avoid them for anything where the thermal coefficient is important.They are cheap. That sums it up.Isabellenhuette also has some nice precision resistors:http://www.isabellenhuette.de/en/precision-and-power-resistors/I have used their SMT series several times. They are specified at only 50ppm/°C max, but their typical coefficient is much better.http://www.isabellenhuette.de/fileadmin/content/praezisions-leistungswiderstaende/SMT.PDF
"High Tech Gadgets" (Chinese comedy) - Page 1
Forum section: electronics / projects

author: cdev
author_rank: Super Contributor
timestamp: January 21, 2022, 11:05:14 pm
content: This is from "From Beijing With Love", a Hong Kong spoof of James Bond flicks starring Stephen Chow

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 22, 2022, 07:17:07 pm
content: I liked the solar torch. Reminded me of a number of "real" green projects.

author: coppercone2
author_rank: Super Contributor
timestamp: January 22, 2022, 07:20:31 pm
content: they must find spies very irritating

author: cdev
author_rank: Super Contributor
timestamp: January 22, 2022, 08:05:16 pm
content: Watch the firing squad scene, its (I thought) pretty funny. Especially the ending, which is consistent with stories I've heard from North Koreans.

author: LaserSteve
author_rank: Super Contributor
timestamp: January 23, 2022, 01:05:16 am
content: The firing squad scene was awesome. Thanks for the tip!Steve
High Temp Batterys - Page 1
Forum section: electronics / projects

author: richcj10
author_rank: Unknown
timestamp: February 06, 2013, 04:57:40 pm
content: I need to use battery's that can reach 80 deg C that is rechargeable.I can't find any! Any help will be appreciated.

author: SeanB
author_rank: Super Contributor
timestamp: February 06, 2013, 05:19:08 pm
content: SAFT do a high temperature NiCd that will run to close to boiling.

author: richcj10
author_rank: Unknown
timestamp: February 06, 2013, 07:03:48 pm
content: Thanks!I have a call into then now.
High temperature, low viscosity epoxy - Page 1
Forum section: electronics / projects

author: blueskull
author_rank: Unknown
timestamp: January 14, 2018, 11:16:17 am
content: If I am going to make a BGA mock up (a small module in a BGA package), what kind of encapsulant should I use?It seems like IC related materials are only traded within the IC business, and they rarely end up in the wild.Is there any way I can get some molding compounds (quartz filled plastic beads) or 2-part epoxy that will survive SAC305 reflow temperature?I'm looking for a small package, less than 0.5 kG. Any suggestions where can I get my hands on such materials?

author: t1d
author_rank: Super Contributor
timestamp: January 14, 2018, 11:22:33 am
content: Research electronic "potting" materials. Some of that should be high temp. Should be available from Mouser, Digikey, etc.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 14, 2018, 11:49:53 am
content: EpoTek will be closed this coming Monday (1/15/18).

author: sdouble
author_rank: Frequent Contributor
timestamp: January 14, 2018, 12:39:49 pm
content: i have a good experience with epotek.serious company.

author: HighVoltage
author_rank: Super Contributor
timestamp: January 14, 2018, 01:39:43 pm
content: In the USA I have used the Ellsworth high temperature epoxy successfully.A great company to work withHenkel Loctite STYCAST 2662 High Temp Epoxy Encapsulant Black 1 qt Canhttps://www.ellsworth.com/products/by-manufacturer/henkel-loctite/encapsulants/epoxy/henkel-loctite-stycast-2662-high-temp-epoxy-encapsulant-black-1-qt-can/

author: lewis
author_rank: Frequent Contributor
timestamp: January 14, 2018, 05:34:22 pm
content: Silicone resin any good for your application?http://uk.farnell.com/electrolube/sc3001rp250g/resin-silicone-optically-clear/dp/2075077Low viscosity, withstands 250*C for 30min, optically clear.
High temperature resistor  - Page 1
Forum section: electronics / projects

author: kozlojak
author_rank: Contributor
timestamp: April 05, 2013, 08:01:28 pm
content: I am looking for a resistor that can operate at 1000 degrees Celsius. Does such a thing exist and can someone point me in the right direction, The pest I can find is 230C

author: G7PSK
author_rank: Super Contributor
timestamp: April 05, 2013, 08:13:39 pm
content: An electric fire element is a resistor that works in that sort of temperature range. you would most likely have to wind them yourself out of nichrome wire on some form of ceramic former. Trouble is the rest of your circuit will melt, copper melts at 1084 deg C.

author: kozlojak
author_rank: Contributor
timestamp: April 05, 2013, 08:17:29 pm
content: Great Idea we have some nichrome wire on hand.Thanks
High temperature  switching problem  - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: September 12, 2017, 12:05:06 pm
content: Hello Sir,I am getting trouble in the switching problem on my device power OFF action.Take a look this circuit and help me.V_BAT_OUT is 3.52 volt, VIN is nearly 4 volt.The schematics says,When this circuit gets power from battery V_BAT_OUT1. PWR_KEY is High,2. firmware check PWR_IND signal3. PWR_KEY is pressed on few moments4. MCU_RST pin will be LOW, that PWR_HOLD as HIGH.but when, VIN is in action1. PWR_KEY is LOW,2. firmware check the PWR_IND signal3. PWR_KEY is release on few moments4. MCU_RST pin will be high, that PWR_HOLD as LOW.In VIN action mode, in maximum temperature, the base of DTC304 giving Higher voltage!!Can you describe the circuit well,Why the diode acts strange is high temperature?How the 3 network in base of DTC304 is performing ?Do you suggest any simulation, how could we control these MCU signal on it?
High value ceramic caps reliability - Page 1
Forum section: electronics / projects

author: ivan747
author_rank: Super Contributor
timestamp: October 08, 2011, 06:19:21 pm
content: Hi, I am converting a board I did to a lower profile design. That meant changing a 47µF electrolythic with a ceramic one. Is the board flex going to affect the capacitance too much, at this high values. Mind you, it's a 1.6mm thick prototyping board with some connector on it. (OK, I admit it. It's an Arduino compatible).Thanks again!

author: Zero999
author_rank: Super Contributor
timestamp: October 09, 2011, 02:24:35 pm
content: Is the capacitance value critical?If so you've chosen the wrong type of capacitor be it electrolytic or ceramic. Electrolytic have a wide tolerance and some (I'm sure others here will remind me of the dielectrics I'm talking about here) ceramics are piezoelectric and have a nasty voltage/capacitance coefficient.

author: Unknown
author_rank: Unknown
timestamp: October 09, 2011, 02:49:12 pm
content: I believe the nasty dielectrics are the class III ones like Z5U and Y5V, which also happen to make it possible to get large capacitance values in small packages. Tantalum may be another option, they used to be the more stable alternative for aluminum electrolytics before high-value ceramics came along.
High value pull-down resistors on two data lines  - Page 1
Forum section: electronics / projects

author: perdrix
author_rank: Frequent Contributor
timestamp: August 27, 2025, 11:08:24 am
content: I'm looking at a schematic which is copied from the original manufacturer's service docs. It has 6k8 pull-ups for all the data lines (D0-D7), but also has 100k pull-downs on D5 and D7???Puzzled... Can anyone explain why that might have been done?David

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 27, 2025, 03:14:40 pm
content: Quote from: perdrix on August 27, 2025, 11:08:24 amNot just that, but the 4116R-1-220 in series with the data lines is a 22Ω 2% ×8 resistor array in DIP-16 package.For signals when everything is powered and connected, the pull-down resistors just don't have any real effect. Even if the left side is high-Z (not connected) and right side is the input, D5 and D7 still get pulled to 100kΩ/106.8kΩ×Vcc ≃ 0.936×Vcc, but all other data lines to Vcc, so a 6.4% difference. (Interesting stuff might occur if the pull-ups are powered from a different power rail than the right-side IC, though.)Four possibilities come to my mind:Pin strapping for right-side IC for cases where the Vcc for the right-side component is present, but not for the 6.8k pull-ups. This ensures that D5 and D7 are low thenWorkaround for a silicon errata on the right-side component, where D5 and D7 need to be at a lower voltage than other data lines, or extra current draw or some instability or other problem may occurLeft-over optional components not always populated on the PCB, that had some significance during development and testingSchematic editor brainfart, or "nobody knows why those are there because the person who did left, but nobody wants to take responsibility for removing them either"

author: Andy Watson
author_rank: Super Contributor
timestamp: August 27, 2025, 04:49:25 pm
content: Quote from: Nominal Animal on August 27, 2025, 03:14:40 pmThey're there as a nod towards line termination - helps to stop ringing on the bus lines. The 100k pull-downs might be there for similar reasons, but why only D7 and D5? Perhaps it was one of those marginal designs that only worked if a finger was placed on the data bus and/or option 4 (been there, done that!)edit:Typo
High volt measurments  - Page 1
Forum section: electronics / projects

author: eddy66t6
author_rank: Contributor
timestamp: November 21, 2013, 03:11:08 pm
content: Looking for any suggestions on measuring high voltage but low current with a multimeterThanks

author: AndersAnd
author_rank: Frequent Contributor
timestamp: November 21, 2013, 03:15:45 pm
content: How high voltages?And is it high voltage or current from a high voltage source you want to measure?DC or AC? What frequency?The more details you give the better answers you will get.

author: Lightages
author_rank: Unknown
timestamp: November 21, 2013, 03:27:20 pm
content: Yes it depends on the voltages of course. One option is something like this:http://www.ebay.com/itm/Fluke-80K-6-HV-High-Voltage-Probe-6KV-PK-Max-Great-Item-Fast-Shipping-/171176234205?pt=LH_DefaultDomain_0&hash=item27dae60cddof course n the appropriate rated voltage for what you want to do.The other thing you MUST do is learn the safety procedures for dealing with high voltages so you don't kill yourself. A few mA passing through your heart will not be a happy day.Generally the one basic rule is when probing around high voltages is to keep one hand behind your back. That way you lower the chances that during a mistake in where you put your hands will pass a current through your heart.Without knowing what you are trying to measure there is not much to be said.
High voltage analogue multiplexer/demultiplexer circuit - Page 1
Forum section: electronics / projects

author: edba
author_rank: Contributor
timestamp: April 17, 2020, 07:00:02 pm
content: HiDoes anyone know how to build a high voltage 8 channel analogue multiplexer/demultiplexer circuit that would be able to switch a high voltage (1500-2000V) to anyone of the eight inputs/outputs whilst the other inputs/outputs were at 0V? It would be like a high voltage version of the 4051.The only way I can think of doing this is by using eight individual high voltage reed relays, but this would be expensive espeicially if I wanted to increase the multiplexer/demultiplexer inputs/outputs?Edba

author: Zero999
author_rank: Super Contributor
timestamp: April 17, 2020, 07:38:20 pm
content: I suppose it's theoretically possible with photocoupled MOSFET solid state relays, but they will have a much higher leakage current and won't be any cheaper than good old relays.

author: Neilm
author_rank: Super Contributor
timestamp: April 18, 2020, 04:12:19 pm
content: I would find some decent relays. You are up at voltages where creepage and clearances are starting to become significant so anything you buy will be esigned to meet them and will start to be expensive for it. SSRs that are good for that level of voltage will be more than a relay.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 18, 2020, 06:36:56 pm
content: What leakage current? What bandwidth, or what maximum isolation capacitance? What transient voltage or current rating?Tim

author: David Hess
author_rank: Super Contributor
timestamp: April 18, 2020, 11:36:52 pm
content: It can be done with a photovoltaic isolator driving a pair of back-to-back high voltage MOSFETs per switch. I have seen one circuit which used 4 of them to make a high common mode voltage flying capacitor to replace a high voltage instrumentation amplifier.

author: edba
author_rank: Contributor
timestamp: April 20, 2020, 04:06:23 pm
content: HiThe bandwidth is DC and leakage current around 150nA,BrEdba

author: Zero999
author_rank: Super Contributor
timestamp: April 21, 2020, 10:21:52 am
content: Then forget about using anything solid state. Relays are the only viable solution. You'll need to pay a lot of attention to creepage distances to get that kind of low leakage current, which would require an insulation resistance of >10G.
High Voltage Board to Board Connectors? - Page 1
Forum section: electronics / projects

author: magicsmoke
author_rank: Regular Contributor
timestamp: June 19, 2015, 04:26:17 am
content: Do high voltage board to board connectors exist?I am trying to create an interconnect between a gate drive PCB and a series of power stage PCBs (which will have different typologies; VSI, CSI, etc.). For desat protection and other features I need to bring the high side switch emitters up to the gate drive board along with bringing down gate signals to the power stage PCB. The DC bus will go up to ~650V. Ideally I would like to make the connection with minimum inductance. What are people typically using for board to board connections at these voltage levels? I haven't really found anything with a high enough voltage rating in a board to board connector style or header style. In the past I have just done everything on a single PCB but in this case it is preferable not to.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 19, 2015, 05:21:02 am
content: What about common 0.1" headers with pins removed to get enough clearance?

author: Marco
author_rank: Super Contributor
timestamp: June 19, 2015, 06:16:35 pm
content: Can't you just use some high current connectors and rely on air gap for insulation? Exposed high voltage is a given any way ...BTW, you forgot to mention if this was vertical or edge connect.
High Voltage Buck converter 65VDC --> 42VDC   - Page 1
Forum section: electronics / projects

author: jeanlion1
author_rank: Newbie
timestamp: December 21, 2021, 08:36:25 pm
content: I have several 65VDC 300mA powersupplies (230V --65VDC) ... I would like to design a buck converter which allow me to regulate the fixed 65VDC output to an adjustable 40 --55VDC output. Is there someone who can guide me thru the design process? Is there an online tool like "TI's webbench power designer" to perform this task properly? I have studied a bit the basics of the buck converter technology, however I lack experience in design.Also I'd like to know which testing gear I'd need to evaluate prototype designs. Then remains question which reverse feedback (reflection) occurs into the existing powersupplies. A device which seems appropritae may be the "STMicroelectronics L7983 Synchronous Step-Down Switching Regulator", however I am open to any other component ideas.Thanks for your ideas and comments.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 21, 2021, 09:14:20 pm
content: TI have an online design tool that's right up your street.https://webench.ti.com/power-designer/switching-regulator/selectYou have to create an account to use it. I put you paramters in and got 35+ potential solutions.
High-voltage Capacitor Charger - Page 1
Forum section: electronics / projects

author: 4beowulf7
author_rank: Newbie
timestamp: July 31, 2015, 07:39:48 am
content: Hi guys,I have designed a high-voltage capacitor charger which charges up a capacitor up to about 500-600V.https://tr.scribd.com/doc/272548770/High-voltage-Capacitor-ChargerGreetings
High Voltage capacitor dielectrics  - Page 1
Forum section: electronics / projects

author: stcoso
author_rank: Regular Contributor
timestamp: May 29, 2023, 12:36:08 pm
content: Hi,I'm trying to choose the best capacitor for my application (Marx generator repair). The actual capacitors are N4700 but they're obsolete and not available. I've found many datasheet and guides on HV capacitors (>30kV, 500pF) but I'm still non 100% sure about the best dielectric. The market at the moment offers mainly N4700, Y5S and Z5T capacitors.As I understand, the better option should be the N4700 dielectric which should:Be a class 1 dielectrichave better tempco/voltcoremain stable over timeIs this correct? Thank you.

author: TizianoHV
author_rank: Regular Contributor
timestamp: May 29, 2023, 07:00:14 pm
content: I don't know if is mechanically doable but as last chance you could use 2*1nF pieces in series (maybe with a balancing resistor in parallel):->https://it.farnell.com/vishay/715c20ktd10/condensatore-disco-1000pf-20kv/dp/3580758?gclid=Cj0KCQjwmtGjBhDhARIsAEqfDEcvKw7-3Cio-Zs4b6YaSO-t_IxKEIUI37eyi4yFnuVprleDGhVb4IQaAsIdEALw_wcB&mckv=_dc|pcrid||plid||kword||match||slid||product|3580758|pgrid||ptaid|&CMP=KNC-GIT-GEN-SHOPPING-PMAX-Med-Roas-Short-Title-Test-21-Dec-22&gross_price=trueYou could try asking here ->https://highvoltageforum.netWould be nice to see some photos of the Marx!Ciao!
high voltage capacitors for low voltage applications? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: January 18, 2014, 07:37:37 pm
content: Is there anything special to know about using those nice HV (100V+ ) electrolytic capacitors for low voltage applications, such as smoothing after a bridge rectifier at low voltage (3-50V)?how about 50V parts in a 5V circuit? Is there any rules?other then they are over sized

author: Rerouter
author_rank: Super Contributor
timestamp: January 18, 2014, 09:39:28 pm
content: generally none, but I believe the esr will be higher for higher voltage units,

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 19, 2014, 12:06:39 am
content: Crap, my fat fingers just trashed my brilliant reply. Have to settle for this one- If you look at the data sheets for a given cap series, the higher voltage parts will have the lowest dissipation factor, at least to a point. I often take advantage of this and use 35-100 volt parts in much lower voltage circuitry. I've seen no downside whatsoever. That said, I'm not fully convinced that it's a good idea to use high voltage parts, say 250-500 in low voltage circuits. I've seen old caps that can't support any more voltage than what they were run at for decades, without large and destructive DC leakage. Of course, you could just call them bad caps that have reached the end of their lives. There's also the size and expense issue, and they don't have the performance advantage that you get with a moderate voltage increases when working under 100 V. There seems to be a sweet spot with capacitor performance between 35 and 100 volts, but above that you might see the dissipation factor stay the same or even increase. Always check the data sheets for the specific behavior.

author: calexanian
author_rank: Super Contributor
timestamp: January 19, 2014, 07:43:39 am
content: Depending on chemistry and production some caps if never run up in voltage may never fully form properly and leak and fail early in life. I recall seeing a minimum spec for pre forming them. Generally speaking you are fine from then out. Best practices I recall is 70% to 80% rated voltage is ideal for maximum cap life after having been formed at peak voltage (Typically just above DCWV) I believe however than most caps are pre formed nowadays.
High voltage coax cable - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: July 19, 2019, 03:40:40 am
content: What type of coax is the "right" cable type, for use at about 3-5 kV DC, with 5kV SHV connectors?It needs to be a patch lead (somewhat flexible and movable) and the cable needs to be the right thickness (no thicker than RG-59, basically) or it won't fit in the connector.RG-59 with solid polyethylene dielectric (not foam) is the best candidate I've found.It also has the right outer diameter for the SHV connectors, and I've seen commercially sold SHV cables that use this type of cable.Belden 8241 is a good example - it is specified in the datasheet at 1700V RMS, but I'm intending to operate it at (DC) voltages a bit higher than that.RG217 is specified for these kinds of voltages, but it's too thick to fit in the connectors.

author: MarkF
author_rank: Super Contributor
timestamp: July 19, 2019, 08:40:26 am
content: Far outside my knowledge...Here are two pre-made cable assemblies with SHV connectors:https://www.pasternack.com/shv-plug-shv-plug-rg225u-cable-assembly-pe34421-p.aspxhttps://www.pasternack.com/shv-plug-shv-plug-rg393u-cable-assembly-pe3338-p.aspxThe RG393 is rated for AC Operating Voltage 3500 Vrms

author: TimFox
author_rank: Super Contributor
timestamp: July 19, 2019, 04:17:03 pm
content: In grad school, we always used solid polyethylene RG-59/U cable with MHV and SHV connectors, but my experience only went to 3 kV, from -hp- 6516A power supplies. I once made the big mistake of using “better” polyethylene-foam cable (lower RF loss and faster velocity), which failed catastrophically.

author: MagicSmoker
author_rank: Super Contributor
timestamp: July 19, 2019, 04:38:06 pm
content: Yeah, foam anything is absolutely verboten if you need high dielectric strength.More than likely, good quality solid PE (good) or PTFE (better) dielectric cable will have more than adequate dielectric strength here, but note that breakdown is almost entirely the result of voids, moisture ingress, cracks or other defects in the insulation, and not the thickness of the insulation itself (PE has a dielectric strength of ~20kV per mm while PTFE is around 60kV/mm).Usually the dielectric strength for coax assumes RF rather than DC and so some allowance is made for dielectric heating, in which case PE is far inferior to PTFE. Of course, it never hurts to actually test samples of cable for breakdown using a current-limited HV power supply; that's what I would do if I planned on exceeding the datasheet ratings here.
High voltage connectors - Page 1
Forum section: electronics / projects

author: Thorr
author_rank: Newbie
timestamp: October 10, 2016, 12:29:01 pm
content: Hi everyone!I am building my own fluorescent lighting driver and I am looking for connectors which are capable of handling voltage spikes of up to 10 kV. They will have to be able to support a maximum current of 1 Amp. Does anyone have experience with such connectors? I have tried searching myself, but I mainly find high current/power connectors which are way too bulky.Thanks!

author: ceoxrad
author_rank: Regular Contributor
timestamp: October 10, 2016, 12:57:56 pm
content: SHV connectors maybe can be suitable, they have a maximum voltage of 5kV and a maximum continuous current >1A. There are some variants with higher ratings but I never used those.Edit:Rating

author: helius
author_rank: Super Contributor
timestamp: October 10, 2016, 12:59:21 pm
content: SHV would be ideal for that application.

author: HighVoltage
author_rank: Super Contributor
timestamp: October 10, 2016, 03:02:27 pm
content: In Germany I buy SHV connectors at a company calledKoax24http://www.koax24.de/steckverbinder/uebersicht/hv-steckverbinder/shv.htmlThey have just connectors and connectors with cable in a lot of different varieties.

author: Thorr
author_rank: Newbie
timestamp: October 11, 2016, 07:49:42 am
content: SHV seems like a proper solution! Thanks!
High Voltage constant load design - Page 1
Forum section: electronics / projects

author: 001
author_rank: Super Contributor
timestamp: October 10, 2019, 04:07:04 pm
content: HiI`m gonna buid constant load to test homebrewered tube power supplies 0-600V 0.6ANothing special exept voltageso I plane to use 807 tubes instead mosfets in nowday common schematic like thisBut problem is that tube bias voltage is about -40voltsIt is greater than opamp power railsWhat the way?Thanx

author: dom0
author_rank: Super Contributor
timestamp: October 10, 2019, 04:41:17 pm
content: Paralleling some high voltage MOSFETs is going to be easier. 2SK1317 have a SOA of approx 150 mA @ 600 V, for example, so ~7 devices in parallel should be sufficiently robust for a .6 A load.Also, narrowing the input voltage and current range allows you to relax pass element stresses a lot by burning power in fixed resistors instead.

author: magic
author_rank: Super Contributor
timestamp: October 10, 2019, 05:07:30 pm
content: If you can accept that the input voltage must be 40V or more...Use anysmall(not so small at 24W, actually) 40V transistor to regulate current and cascode it with the tube, tying the grid to ground.editFor voltages less than 40V the tube could be bypassed.

author: aheid
author_rank: Regular Contributor
timestamp: October 12, 2019, 12:52:55 pm
content: I'm by no means an expert, so this might be silly.You're asking the tubes to dissipate 360W, Wikipedia says a single tube can do 25W max, so that's gonna be a lot of tubes.At 600V, the equivalent resistance of 600mA is 1k Ohm, which at 360W should be doable as a regular resistive load. Then if you hook your dynamic load in parallel to this 1k resistor, the pass element only has to do <100W according to my sim. Maybe use a bit higher resistance so you have some headroom, 1.1k would work up to 650V and keep pass element still <100W.The 2SK1317 mentioned can barely do it within the specified SOA, though if I made this circuit I guess I'd put two in parallel to be on the safe side. It's also specified as a switching transistor, not sure how reliable the DC SOA is.Then again, what do I know, maybe a dumb idea?In any case, do you really need it to go all the way down to zero?

author: dom0
author_rank: Super Contributor
timestamp: October 12, 2019, 04:11:06 pm
content: MOSFET DC SOA generally doesn't account for or underestimates Spirito effect, so they should always be taken with a grain of caution. However, for a reliable design in practice you need 100 % or more safety margin on top of SOA anyway. That's why I recommended at least seven of these MOSFETs in parallel to handle this load earlier. Of course, if you use dumping resistor(s), the load imposed on the pass element is greatly reduced, so you can do with fewer FETs.
High Voltage CW Phase Shifter - Page 1
Forum section: electronics / projects

author: Univie
author_rank: Newbie
timestamp: August 19, 2020, 04:35:18 am
content: My goal is to generate two identical high voltage continuous-wave signals of around 3-5MHz, one being shifted by around 63 degrees relative to the other. The outputs are capacitive.I’m currently achieving this using a simple ’slayer exciter’ circuit to generate the first HV signal, and a capacitively coupled air-core coil to generate the other. The coil is tuned slightly inductive (>90deg) to generate the needed phase shift.The problem with my very simple setup is that the self-tuning of the slayer exciter is disturbed by the capacitive coupling of the passive coil, unless the coupling is kept very low. I’d be happy to hear suggestions of an alternative method that would not be sensitive to this coupling effect.

author: bob91343
author_rank: Super Contributor
timestamp: August 19, 2020, 06:25:11 am
content: You are taking the output from the most sensitive point, the base of the transistor. I suggest adding an emitter resistor and taking the output from the emitter.I ran into a similar question years ago when a student was trying to send a signal but the stability was poor. Taking it from the emitter helped a great deal but still too sensitive. I suggested a crystal oscillator, which solved the problem. He won a cash award with that and I asked for my cut. He started to panic so I told him I was just kidding.

author: Univie
author_rank: Newbie
timestamp: August 20, 2020, 06:27:35 am
content: Thanks for the reply, I may have to consider a crystal oscillator, since I also need bipolar output, while the slayer exciter has the secondary grounded at one end. (I still get bipolar output now, but only because my 'ground' consists of a small heatsink on the bjt). Do you think that tuned-circuit oscillators like Colpitts or grounded-base would also be disturbed by the coupling of the secondary to another coil capacitively?Or could I have a single oscillator driving two primaries (see diagram), which induce currents in two different secondaries, such that the phase shift between the secondaries is the required phase shift. For example, the first secondary could be slightly capacitive (relative to primary) by half the needed phase-shift (31.5 deg), and the other secondary slightly inductive, providing the other half of the phase shift. Would a crystal oscillator topology allow for something like this?
High Voltage Differential Probe Design Help - Page 1
Forum section: electronics / projects

author: atomic antics
author_rank: Newbie
timestamp: February 10, 2017, 06:19:24 pm
content: Hi everyone,I'm working on a high voltage differential probe to help troubleshoot the primary of my tesla coil. This is my first PCB design project that requires some serious thought about design and layout to maximize bandwidth, so I'd like some feedback.I have been using this page as a bit of a guide, but have also simplified it down some to have fewer parts and also worked on the CMRR.https://www.eevblog.com/forum/projects/oshw-diy-1kv-100mhz-differential-probe-(dilemma-vs-hope)/Requirements:+-2kV input transient, +-1kv minflat response out to 20MHz6-10Meg input impedanceShort summary of design:I am using a high impedance voltage divider to divide the input signal down to tolerable levels. I can select between 1/1000 and 1/100. The total impedance is around 7Meg. I am aware that this will introduce nyquist noise, but I do not really see any better options. IThis is fed into an instrumentation amplifier. The input buffers are made from jfet op amps (opa659) and the subtracting amplifier is the LM7171.The output is BNC through coax to my oscilloscope.The op-amp power supply uses 6.5V switching converters, some filters and then 5V linear regulators to hopefully bring the ripple down around 1mV.I attached a PDF document with screenshots of the schematic and layout. I would appreciate any feedback on that.Currently, one of my largest concerns is reflections. I tried to keep trace lengths as short as I could and maintain a continuous ground plane beneath signal traces, but I do not know much about reflections other than sudden changes in impedance can cause them. Is this something I need to worry about? I am specifically concerned about the output of the probe (low impedance diff amp output) to my scope input at 1Meg 20pF.Thanks in advance for any help!

author: David Hess
author_rank: Super Contributor
timestamp: February 10, 2017, 08:51:08 pm
content: The high impedance attenuators are going to require frequency compensation. High voltage ones typically use a distributed capacitor on the input resistor and an adjustable capacitor on the shunt.Instead of making the input attenuator x1000/x100, make it x500/x50 so that a 50 ohm series termination on the output can drive a 50 ohm oscilloscope input for an additional x2 factor making x1000/x100 total. That gets rid of any issues with driving the oscilloscope.Or just make the cable between the instrumentation amplifier output and the oscilloscope input short.The instrumentation amplifier should have adjustments for DC and AC common mode rejection.Instead of building your own probes, I would consider using a pair of existing x100 or x1000 oscilloscope probes with a home built differential amplifier to drive the oscilloscope. You still need the buffers and instrumentation amplifier but it saves trying to figure out how to get the high input impedance attenuator to perform well.
High Voltage Digital Pots. - Page 1
Forum section: electronics / projects

author: PeterG
author_rank: Frequent Contributor
timestamp: October 13, 2022, 10:42:42 pm
content: G'day all,i have been searching high and low for these for a couple of months now. I am looking for 100K and 50K digital pots that are 18V tolerant. I also need then to be SPI with daisy chain ability.There are a couple of options via Element14 etc. However they are out of stock and wont be available in the near future.Does anyone know of a chinese part that i can use? I have checked LCSC but can't seem to find anything that will handle this voltage.Regards

author: exe
author_rank: Unknown
timestamp: October 22, 2022, 07:18:25 am
content: > I am looking for 100K and 50K digital pots that are 18V tolerant.I've never seen such. All devices I've seen were 5/3.3V only. May be an alternative option would be a DAC+opamp? How are you going to use your digipot?

author: MasterT
author_rank: Frequent Contributor
timestamp: October 22, 2022, 01:16:07 pm
content: Moser has MCP41HV51-104E/MQPackage is another question

author: PeterG
author_rank: Frequent Contributor
timestamp: October 22, 2022, 10:38:17 pm
content: The current design is for 5v logic with up to 18v across the wiper of the pot. The device is a audio system that will use 8 of these pots using spi. Hopefully i can daisy chain the spi on the pots to minimise pin usage on the mcu. Unfortunately the MCP41HV series do not daisy chain.
High Voltage Down Converter Circuit - Page 1
Forum section: electronics / projects

author: Pat Pending
author_rank: Regular Contributor
timestamp: September 12, 2012, 11:36:41 pm
content: Does anyone know of a simple discrete DC/DC down converter from 75V to 12V@20mA?

author: mariush
author_rank: Super Contributor
timestamp: September 13, 2012, 01:09:25 am
content: That would be kind of hard to get one ready made, you have lots of options if you get that down to a maximum of 72v :http://www.digikey.com/product-detail/en/VWRBS2-D48-S12-SIP/102-1519-ND/1558914http://www.digikey.com/product-detail/en/VWRAS2-D48-D12-SIP/102-1535-ND/1558930But you could build one yourself if you don't need it to be the isolated kind, look up the LM500x family of switching regulators. They take up to about 95v DC and regulate down to whatever you want, and they're about 2-3$ in 10-50 pcs quantity:http://www.digikey.com/product-detail/en/LM5008AMM%2FNOPB/LM5008AMMCT-ND/2075647http://www.digikey.com/product-detail/en/LM5009MM%2FNOPB/LM5009MMCT-ND/1001314http://www.digikey.com/product-detail/en/LM5007MM%2FNOPB/LM5007MMCT-ND/599064Add a couple of dollars in inductor, resistors and capacitors and you're done, cheaper than an isolated dc-dc converter.

author: PSR B1257
author_rank: Frequent Contributor
timestamp: September 13, 2012, 06:29:52 am
content: If you only need 20mA you might use a linear regulator - like the TL783 - instead.As every other voltage regulator of that kind, it's programmable with just two resistors.What kind of 12V/20mA load is this? If the 20mA are constant, you need just a single resistor.

author: Pat Pending
author_rank: Regular Contributor
timestamp: September 13, 2012, 07:30:17 pm
content: Thanks EveryoneI'd been looking at the MAX5033, but then two issues arose, 1st it's expensive in small quantities and 2nd it's by Maximor rather no one carries a large stock whereas the LM500x is carried in the many thousands.I was hoping for some sort of jelly bean buck converter if one still exists?

author: PSR B1257
author_rank: Frequent Contributor
timestamp: September 13, 2012, 09:10:11 pm
content: What about my questions...To give you a propper suggestion, we need to know what you intend.
High voltage electronic load for PMT supply testing - Page 1
Forum section: electronics / projects

author: speakerguy
author_rank: Newbie
timestamp: January 02, 2019, 03:44:47 pm
content: Hey guys,Odd request here - I'm needing to test a high voltage power supply for a PMT detector. We design these occasionally and our test systems are usually thrown together by whatever engineer gets assigned. I'd like to just buy a load bank and write some PyVisa code to automate testing and be done with it for all eternity. Does anyone know of an electronic load that will handle 2kVDC (min) to 5kVDC (nice to have) and maybe also measure ripple and noise? I would love to not have every engineer re-think how to adequately test a new PMT supply every time we have to modify a design.Thanks for any help.

author: David Hess
author_rank: Super Contributor
timestamp: January 02, 2019, 04:50:31 pm
content: I am dubious that anybody makes a suitable electronic load.A PMT application uses a series string of high voltage resistors to create the dynode voltages. I would use that as the test load.

author: speakerguy
author_rank: Newbie
timestamp: January 02, 2019, 05:30:11 pm
content: Agreed, I am having trouble finding anything. We typically test them either with the intended PMT itself or with a string of resistors, but if something in this space exists it would be a nice find.

author: ConKbot
author_rank: Super Contributor
timestamp: January 03, 2019, 07:14:44 pm
content: https://www.appliedkilovolts.com/product.cfm?prod=hpzhavent heard of or used this company before, but a 4 quadrant power supply seems like a good starting point. Is 400uA enough current?Edit: looking at the datasheet, it's a Harris owned company. Bring your checkbook.

author: speakerguy
author_rank: Newbie
timestamp: January 04, 2019, 12:31:44 am
content: Awesome, thanks! And I'm consulting so it's their checkbookBut yeah 400uA will cover most all use cases. Thanks again!
High voltage filter  - Page 1
Forum section: electronics / projects

author: LoneWolf6912
author_rank: Contributor
timestamp: June 04, 2024, 09:12:49 am
content: Hello everybody,I am desperately looking for a device that could filter out harmonics beyond 70kHz from a 5kV DC signal that can go up to 1 ampere. Unfortunately, general websites like Farnell or RS-Pro do not seem to have this kind of highly specific equipment.Has anyone here ever come across something like this?Thanks in advance for your help!Tim

author: moffy
author_rank: Super Contributor
timestamp: June 04, 2024, 10:05:00 am
content: You start with high voltage caps like,e.g. 1nF/6kV:https://www.digikey.com.au/en/products/detail/vishay-beyschlag-draloric-bc-components/S102M59Z5UU83L0R/2356791and then choose a suitable inductor that can withstand the expected ripple and load voltages and build your own LC filter. You might want to dampen the resonance of the LC with some resistance. Take care because capacitance at such voltages can provide nasty jolts.

author: Marco
author_rank: Super Contributor
timestamp: June 04, 2024, 10:45:37 am
content: Can you drop some volts? If so and the load never shorts, you can use a capacitor multiplier with a low voltage high bandwidth transistor.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 04, 2024, 06:45:47 pm
content: Above a few 100 volts you get into the world of "medium voltage" prodcucts, then you're into serious power and serous cash. You can get off the truck solutions but they will cost more than a house.Building a low pass filter that passes DC @ 5kV is not trivial.We need to know more about the DC signal. Does it have a rise time you need to preserve?What attenuation is required at 70KHz? To get high attenuation at 70kHz the filter is going to have to begin to roll off at a lower frequency.As we can't make a passive "brick wall" filter with infinite attenuation at a particular frequency,a 3db (0.5x attenuation) point and a roll off slope need to be defined. The 3db point is where the slope starts "Filter order" alters the slope.You'll see filter calculators that use 50 Ohms as a typical characteristic impedance.That's only going to give accurate in controlled impedance circuits.If you can, define a source and load impedance based on your actual scheme. If not your lumbered with 50ohmsSo, there are many on line filter calculators. No problem there.This is one of the besthttps://markimicrowave.com/technical-resources/tools/lc-filter-design-tool/Inductors, hand wind from thick magnet wire. Easily sourced in 7kV and higher rated types. Wind on to nylon or acetal. Clear heatshrink looks cool. (BTW if you're the kinda person that uses flames to make it shrink, this not a project for you.) Add blade connectors etc. Nice.Caps above 100-220n @6kV start to get very expensive. So try to design a filter that doesnt need large caps.You also have to contend with the 100% lethal energies stored in these caps. How will you dump all that, huge bleeder resistors and such?Magic smoke, forgotten insurance premiums, funerals, troubling inquiries etc to follow if ignored.