hybridfree/eevblog-posts huggingface dataset:
Equivalent resistance in voltage divider into ADC - Page 1
Forum section: electronics / projects

author: JJalling
author_rank: Unknown
timestamp: August 20, 2024, 06:07:03 am
content: Hello,I had a brief discussion with a co-worker about a design we are working on, where we use a voltage divider into an ADC, to "program" the board/HW revision for the firmware to detect.The microcontroller we are using is a MSP430FR5969-SP.Our circuit does look like this. No buffer or anything, just the voltage divider directly into the ADC.When comparing this to the circuit in the MSP430 user guide (https://www.ti.com/lit/ug/slau367p/slau367p.pdf, fig. 34-7, pg. 875) - what resistance is the ADC seing. Or in other words, what is the equivalent of Rs?I would say somewhere near the 32k (top resistor in the divider), whereas my co-worker is saying that it is 32k in parallel with the 1k. Who is closest to the answer?BR Jonas

author: moffy
author_rank: Super Contributor
timestamp: August 20, 2024, 06:22:14 am
content: Your co-worker is correct it is 1k in parallel with 32k bypassed by the cap, or just under 1k. It's the Thevenin equivalent.

author: JJalling
author_rank: Unknown
timestamp: August 20, 2024, 06:26:50 am
content: Thank you!BR Jonas

author: Siwastaja
author_rank: Super Contributor
timestamp: August 20, 2024, 07:49:10 am
content: Yeah but you are having that Cpext with a large enough value to make a difference. Equivalent series resistance of the capacitor is near zero. And the capacitor supplies the ADC input.The tad below 1k impedance of the resistor divider then supplies the capacitor. If you sample at high sample rates, capacitor has no time to charge from this divider network, and the 1k impedance of the divider dominates in ADC error. But if you sample rarely (maybe once, or at a few tens of Hz), then the capacitor's low ESR dominates and the 1k impedance of the divider is meaningless.In other words, without capacitor, resistor divider impedance has to be low enoughrelative to samplingtime. With capacitor, resistor divider impedance has to be low enoughrelative to samplingperiod. These are usually very different; sampling time might be configurable on the ADC, but it could still be microseconds. Period is as chosen by ADC trigger logic; e.g. you can trigger it in software or using a timer only at, say, 1Hz.You can expect error in the ratio of that capacitor and internal sampling capacitor. 10nF is kinda awkward value because while it is large enough to work, it is small enough to limit accuracy around 10 bits or so (with typical C_sampl values of around 10pF). You likely have a 100nF or even 1uF part in your BOM already, so use it instead and get a few extra bits, of course limiting bandwidth even more, but that is already limited anyway due to unbuffered resistor divider.

author: mikerj
author_rank: Super Contributor
timestamp: August 20, 2024, 08:59:12 am
content: Quote from: Siwastaja on August 20, 2024, 07:49:10 amWith the caveat that a capacitor cannot correct for ADC input leakage current. Modern ADCs tend to have low leakage, but that's not always the case e.g. some of the 18F PICs were pretty poor.
Equivalent Resistor Calculator (also doing parallel calculations) - Page 1
Forum section: electronics / projects

author: Decap_dk
author_rank: Newbie
timestamp: July 14, 2011, 11:24:11 am
content: Hi allI just wanted to share this project that I have been working on as it is something I constantly need during my work when designing electrical circuits and thought someone here might want to check it out.If you like me sometimes need a specific resistor value that is not attainable using standard resistor values (E12, E24 etc.), or you need to reduce the number of different resistors you use in a project (reduce BOM), you might resort to parallel coupling multiple resistors to get the desired value.This is normally tedious work (for me at least) of inputting the resistor values into a parallel resistor calculator so I decided to make a application that did the reverse. You input the desired resistor value, standard resistors to use (E12, E24 etc.) and the amount of parallel resistors to use and out pops the values to use and the deviation (%) from ideal.It application is called Equivalent Resistor Calculator (or EqReCa):http://code.google.com/p/eqreca/So for instance if you need 310 ohm you need to use E96 to get within 1% of this using a single resistor! Or you could use parallel resistors. In the app you then input that you want to use E12 and 2 resistors in parallel and out pops the answer that you should use 1500 and 390 in parallel to achieve 309 Ohm equivalent resistance.I also implemented a standard parallel resistor calculator just for the fun of it...But please check it out and tell me what you think.Often I also use this to minimize the different resistors in a project so I am working on the ability to input your available resistors in your BOM and use this as a basis for the calculations and not just the standard E12/24/48 etc.

author: jahonen
author_rank: Super Contributor
timestamp: July 14, 2011, 11:42:19 am
content: Some similar tools already exists, but I guess that one can never have too manySeehere.Regards,Janne

author: Unknown
author_rank: Unknown
timestamp: July 14, 2011, 12:12:54 pm
content: Check the CAD tools sticky topic on this forum. There is also another one called Rescalc and yet another one called Resistor CAD.

author: ivan747
author_rank: Super Contributor
timestamp: July 14, 2011, 03:28:42 pm
content: I have always been interested in learning the most efficient algorithm for doing this job.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 15, 2011, 12:34:18 am
content: Grab a bunch of resistors,a Scientific Calculator & a DMM,& you'll do it in half the time!VK6ZGO
Equivalent to 5A Solar Panel Up to 300V? [SOLVED] - Page 1
Forum section: electronics / projects

author: KerimF
author_rank: Frequent Contributor
timestamp: August 06, 2024, 07:43:53 am
content: Hello,I wonder what the simplest topology (efficiency is not important) could be for a 5A DC current source whose open voltage could be up to 300Vdc.I guess having a 24Vdc supply (a power battery for example) is better than starting with 220Vac (50Hz).Thank you,Kerim

author: KerimF
author_rank: Frequent Contributor
timestamp: August 06, 2024, 11:15:14 am
content: Let us recall that DC voltage source to DC voltage supply is rather easy to do.But, as you likely found out, DC voltage source to DCcurrent supplyis not easy at all.Cheers.

author: KerimF
author_rank: Frequent Contributor
timestamp: August 07, 2024, 07:30:04 am
content: Thinking out of the box, it became possible to find a practical topology/circuit for this special tester/tool (by emulating a solar panel in order to test various repaired solar inverters).
Equivalent to Analog device ADUM2401CRWZ - Page 1
Forum section: electronics / projects

author: viji_rookie
author_rank: Contributor
timestamp: June 29, 2016, 09:20:03 am
content: Help me to determine if these components are equivalent;Using Analog device -ADUM2401CRWZ; is Silicon Labs SI8641ED is equivalent.Functionality of both device is same , concern is with lower output current compared to Analog part ..Is that should be okay ?

author: XFDDesign
author_rank: Frequent Contributor
timestamp: June 30, 2016, 04:10:51 pm
content: When you say "lower output current" I have to assume you mean the driver output. Both parts specify their output voltage for a given current load and appear to be equivalent. (4mA source/sink voh min Vdd-0.4 (ADI and SI both), vol max 0.4 (ADI and SI both))What is it you're looking at that is actually different?

author: viji_rookie
author_rank: Contributor
timestamp: July 21, 2016, 01:40:17 pm
content: Hi ,Yes you are right . Thanks !The AD part is currently is used in my design. I just wanted to go with this low cost SI part. Just wanted hear from you guys the difference I found in the source and sink currents. ?
equivilent solid state pneumatic capacitor to electrical capacitor - Page 1
Forum section: electronics / projects

author: Capernicus
author_rank: Frequent Contributor
timestamp: May 19, 2022, 10:58:52 am
content: So when you have a pneumatic capacitor, does it have a 100% solid state pnuematic equivilent to an electrical capacitor?

author: Zero999
author_rank: Super Contributor
timestamp: May 19, 2022, 02:06:36 pm
content: No.

author: jpanhalt
author_rank: Super Contributor
timestamp: May 19, 2022, 02:18:15 pm
content: No.Its capacitance doesn't decrease with voltage/pressure.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 19, 2022, 02:41:19 pm
content: All water analogies are limited. Charge does not behave like water and charge density can tend to infinity. At which point you'll blow up the entire universe.
Erdi current source - Page 1
Forum section: electronics / projects

author: tree
author_rank: Regular Contributor
timestamp: December 22, 2013, 07:42:15 pm
content: I have attached an excerpt from Designing Analog Chips by Hans Camenzind regarding the Erdi current source. The text says that collector voltage of Q3 rises due to an unbalance in Vbe of Q3 and Q4. I understand that the Vbe of Q3 is 29mV higher than the Vbe of Q4 due to multiple emitters (which simulate larger emitter area). How/why does the collector voltage of Q3 rise?

author: kxenos
author_rank: Frequent Contributor
timestamp: December 22, 2013, 11:03:32 pm
content: I think you're right. Normally Vbe3 should conduct less current for Vbe5 to rise enough to equalize the difference. And thus Vbe3 should be 29mV lower than Vbe4.
ERNI connector replacement suggestions - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: March 17, 2019, 07:39:38 am
content: Hi,I have a board Assembly that I want to build, the problem is that there is one DIN 41612 30Pin 3 Row Erni connector on itThe part number of the ERNI connector is 374856 Mate: 284173, the problem with that is that only mouser have it for now and the price is not reasonable! so I want to know if you know some other brand replacement for that, searching digikey showed some harting ones, but there was no female one that matches this one, Also lcsc seems to do not have any DIN41612 connectors, I prefer Asia or china brands. the connectors has long terminals that are required for the assembly.any hints?
Erratic WS2813 - Page 1
Forum section: electronics / projects

author: artag
author_rank: Super Contributor
timestamp: July 18, 2021, 11:15:30 pm
content: I have an installation that runs about 1600 leds using 4 channels of teensy's octoled. I have problems with occasional flashes that disrupt the patterning. After bringing the leds out of storage recently I've had further problems with, for example, a run of leds getting stuck 'on' while the pattern continues to exist (and cycle) around them. Also had individual leds stuck on.This might be put down to a bug in the software on the teensy3.5, but i've also occasionally seen that flash with a simple short-length arduino based test jig. And that 'stuck pattern' - i can't get rid of it by rebooting the teensy but I can if I power the leds down.I believe I have plenty of power (I run a 24V distribution system with multiple buck converters to give local 5V regulation) and optoisolated data. The stuck leds are not at the start of the strip, where data corruption from the cable might appear - they're well down the strip where the driver is another led a fraction of an inch away.There is also some temperature dependence with lots of bad behaviour when first switched on that settles down after a while.Does anyone else suffer these problems ? I'm begining to think they're a flaw in the 2813 system.Maybe the devices don't track each other's rise/fall/bit times when temperatures are widely different ? Maybe they misdetect a faulty data line and switch wrongly to the backup data line ? Maybe they hold some internal state beyond the brightness and the shift register such that they can get stuck where the ws2812 would be refreshed on the next data cycle. Helpful if the adjacent led is broken, but makes corrupted data more visible.
Error in MPF102 datasheet ? - Page 1
Forum section: electronics / projects

author: ferdieCX
author_rank: Regular Contributor
timestamp: July 01, 2025, 06:21:18 pm
content: Hello,I have put to my students as an assignment, that they had to project an IF amplifier at 455 KHz using a MPF102 (just because it was easy available)When I was going to evaluate the stability, I was surprised with the value grs = 0.1 mS.It seemed to big, so I looked at the AN-6609 from Fairchild about Process 50 FETs.I seems that the value should be much lower, like between 1 uS and 10 uS and the amplifier would meet the Stern criterion.I built the amplifier and confirmed that it was stable.I guess that there is a printing error in the fig. 7

author: moffy
author_rank: Super Contributor
timestamp: July 01, 2025, 10:40:11 pm
content: If I'm reading this correctly then a Reverse Transfer Admittance of 0.3mmohs@100MHz equates to about 0.5pF D-G capacitance, which seems reasonable, but I might be looking at the wrong thing, it's been a while since I last looked at Y parameters.

author: TimFox
author_rank: Super Contributor
timestamp: July 01, 2025, 10:56:53 pm
content: y=g+ jbis a complex number.For the FET,bcomes from the feedback capacitance, and the graph shows it rising with frequency as expected.I can't find any other datasheets for the MPF102 on line.As you pointed out, the value for the imaginary componentbis consistent with 0.5 pF D-G capacitance at 100 MHz, so the vertical scale calibration is OK for the imaginary component.

author: ferdieCX
author_rank: Regular Contributor
timestamp: July 02, 2025, 02:16:32 am
content: Hi,It is not brs what troubles me. My doubt is about grsI include a picture of the Process 50, the one that uses Fairchild to produce the MPF102 and other FETs like the BF256

author: TimFox
author_rank: Super Contributor
timestamp: July 02, 2025, 02:47:35 am
content: In that posting,grsis shown with a "x 0.1" next to the curve, but only shown above about 200 MHz.

author: moffy
author_rank: Super Contributor
timestamp: July 02, 2025, 03:20:57 am
content: Seeing that the process curve changes with frequency but the datasheet curve for Grs is flat, I think they are only specifying a worse case value over the frequency range.The fewer parameters they have to specify the easier the qualification testing is and fewer the rejects.

author: ftg
author_rank: Frequent Contributor
timestamp: July 02, 2025, 07:21:44 am
content: Where are you getting your MPF102's?Onsemi has obsoleted it some time ago and the availability has been getting worse.Even when it was in production MPF102 was apparently known for it's wide spread of parameters.Which likely lead to it's mixed reputation due to folks getting very different results for the same circuit.

author: ferdieCX
author_rank: Regular Contributor
timestamp: July 02, 2025, 06:11:56 pm
content: I got the MPF102 from Jameco in November 2021.They are performing ok and the amplifier is stable, something that would not happen in the event that grs = 0.1 mSQuote from: TimFox on July 02, 2025, 02:47:35 amI guess, that in the flat curve for grs in the MPF102 datasheet a "x 0.1" is missing
ERSA hack welder sensor - Page 1
Forum section: electronics / projects

author: salviador
author_rank: Regular Contributor
timestamp: November 20, 2020, 10:42:31 am
content: Hi, I have a old ERSA station.has a soldering iron with an NTC sensor.I want to replace it with a soldering iron that has a thermocouple sensorI noticed that it uses a U106BS integratedHow can I modify the scheme to make this thermocouple sensor read?

author: rvalente
author_rank: Frequent Contributor
timestamp: November 20, 2020, 11:49:51 am
content: AFAIK the ICL only read's out the thermocouple temp as the U106BS is the controllerI suppose you know really well this NTC characteristics if not, it will be a nightmare to set and keep temperatures, NTCs are mean creaturesThe U106BS is a op-amp + zero voltage detector.https://datasheetspdf.com/pdf-file/535241/VishayTelefunken/U106BS/1Check page 9, there is a example for using NTCsThermocouples are very linear sensors were NTCs are really exponential, so you'll need to change the ICL circuit to read NTCs, I'd check its datasheet and old app note, probably there is a suggestion for a NTC thermometer.

author: ch_scr
author_rank: Frequent Contributor
timestamp: November 20, 2020, 12:20:15 pm
content: The schematic shown also uses a thermocouple, not an NTC. "Thermoelement" = Thermocouple. 51uV/°C means type J thermocouple. It's on pin 2 (-) and 3 (+) of the Soldering station connector.
ERSA soldering station: converting to battery dc (make it portable) - Page 1
Forum section: electronics / projects

author: manu
author_rank: Regular Contributor
timestamp: June 11, 2018, 10:48:10 am
content: Hi,Do you think it's possible to convert a Ersa soldering station to be powered from a 18V tool battery?I see this on the forum which is a simple triac controlled ac 24V temperature regulated station:https://www.eevblog.com/forum/repair/ersa-i-con-1-teardown-and-repair-(success)My main concerns should be the triac control which might not work well. The trigger may be continuously on after the first pulse and it would defeat any temperature control...Considering that, it might be easier to have a small inverter... What do you think about it?
ESD Equipment Reviews - Page 1
Forum section: electronics / projects

author: ahoot
author_rank: Newbie
timestamp: January 01, 2019, 07:56:14 pm
content: New user here. Wondering if anyone can suggest any reliable sources of independent testig/reviews of ESD equipment. I'm currently in the market for a Field Service Kit (fold up mat), but may also be looking for a permanent desk cover solution in future.Thanks in advance!

author: GreyWoolfe
author_rank: Unknown
timestamp: January 02, 2019, 12:29:31 am
content: I have had a portable Desco mat in the past and have a Desco mat and ground point on my bench. I don't have Desco wrist straps but when I replace my ground point, I plan to get one. All based on recommendations made to me.You can find some Amazon reviews, I have never seen professional reviews on the 'net.

author: LapTop006
author_rank: Unknown
timestamp: January 02, 2019, 11:06:04 am
content: I also use a Desco mat on my lab desk, got it in 2012, and it's almost perfect to this day. Would happily buy again.Also picked one up recently for our soldering bench at work since they kept buying non-high-temp-safe ESD mats, so far it's doing well there.All that said, not cheap.

author: GreyWoolfe
author_rank: Unknown
timestamp: January 02, 2019, 12:36:13 pm
content: Quote from: LapTop006 on January 02, 2019, 11:06:04 amCheap isn't good, good isn't cheap for sure.

author: LapTop006
author_rank: Unknown
timestamp: January 02, 2019, 02:48:45 pm
content: Quote from: GreyWoolfe on January 02, 2019, 12:36:13 pmBeen burnt too many times by expensive crap to follow that missive too strongly, although mostly with software.

author: GreyWoolfe
author_rank: Unknown
timestamp: January 02, 2019, 08:19:43 pm
content: Quote from: LapTop006 on January 02, 2019, 02:48:45 pmBeen burned that way with tools, myself. Sometimes though, the cheap tools surprise you. I have a Harbor Freight cheap compressor and nail guns that are 13 years old and still work, though they are occasional use tools. A friend of mine nicknames Harbor Freight as the one use tool store.
ESD grounding plate question - Page 1
Forum section: electronics / projects

author: xrunner
author_rank: Super Contributor
timestamp: July 07, 2016, 10:28:11 pm
content: So I got this item today, and I'm not sure I understand something about it. What are the two snap-on connectors there for? The two banana sockets are connected to the green ground wire ground - so far so good. But the other two connectors are NOT connected to ground nor are they electrically connected to each other. They are just ... there, why?

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: July 07, 2016, 10:38:57 pm
content: They're there to store the wrist strap cord when it's not snapped on the wrist strap

author: xrunner
author_rank: Super Contributor
timestamp: July 07, 2016, 10:40:03 pm
content: Quote from: ChunkyPastaSauce on July 07, 2016, 10:38:57 pmAh OK duh ...

author: bitslice
author_rank: Frequent Contributor
timestamp: July 07, 2016, 11:26:51 pm
content: That's a really bad design, as other earthing boxes use the same connections to earth the ESD mats via a 1Mohm resistor.Best not to mix up different practices.It would also fail a Production Quality Assessment,Before you enter a static safe area, both the wrist strap and wrist cable, as well as a heel strap must be checked for continuity.by leaving the wrist cable at your bench then you are not performing this check.Most people just remove the entire thing and leave it in their coat pocket, never seen anyone try to unsnap one before, that's asking for a broken cable.
ESD Information - Page 1
Forum section: electronics / projects

author: custompc48809
author_rank: Newbie
timestamp: March 07, 2014, 01:58:54 am
content: Hey Everyone,I have my ESD Mat and strap setup for when I am working on projects but I have a current tester the ones that detects current just by the tool next to it not attached to the wire. Anyway my setup has current going through it according to that tool. Is there something wrong with my setup or is it just because it it coming from the ground wire?

author: Alphatronique
author_rank: Regular Contributor
timestamp: March 07, 2014, 03:01:28 am
content: Himake sure your setup was rightif take multimeter whit one lead on 120V socket (on the wides blade) and wire that go to your matnormally you have 0 or very low voltage presenthttp://en.wikipedia.org/wiki/File:NEMA_simplified_pins.svgmat must be on the gronund some measure from ground to netral for see normally 0 voltif from mat to hot you have 0 volt mat was on the hot and that not good at all ...measure from mat snap since mat have dissipative surface so > 100meg ohm (old conductive mat was to dangerous)Best regard

author: G7PSK
author_rank: Super Contributor
timestamp: March 07, 2014, 02:25:14 pm
content: Is that a current or a voltage detector, I have a voltage detector that tells me the brick walls of the house are live. In fact it says just about every thing is live except the ground outside on the lawn.
ESD issue on 16X2 LCD display - Page 1
Forum section: electronics / projects

author: sri5496
author_rank: Newbie
timestamp: March 14, 2015, 09:17:49 am
content: hi all,In one of my projects i was using a 16X2 lcd display(http://uk.rs-online.com/web/p/lcd-monochrome-displays/7200207/?searchTerm=7200207&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3732303032303726) with atmega 328 micro, its failing in ESD test at 2kv and 4kv, its not resetting the micro controller but the screen goes gibberish, it seems like the data lines from micro or getting effected, it would be great if you guys can help me out for any possible fixesthanks in advance.

author: Psi
author_rank: Super Contributor
timestamp: March 14, 2015, 09:22:36 am
content: Those LCD modules have a few chip on board IC's to control the screen and provide the API interface. It will be one of those chips which is being scrambled by the ESD pulse.It probably needs more decoupling caps on it or an ESD diode.Also check that you have pullups/downs (or whatever is recommended) for any I/O pins on the LCD module that you are not using.

author: Niklas
author_rank: Frequent Contributor
timestamp: March 14, 2015, 11:29:41 am
content: We had a similar issue with a 2x16 alphanumeric Chip On Glass LCD inside a chrome plated plastic housing.The first issue to solve was the permanent damage to the LCD module that occurred on some prototypes. Exposed chip with less than 0.5 mm air gap to the chromed housing... Added a piece of insulating tape and that was fixed.The second issue was the garbled output on the display in combination with the demand for full recovery after the disturbance is gone and without user interaction. It was not possible to use the busy flag (poll of data bit 7) on the Chinese display we used to detect if the display had passed the initialization. Instead I wrote a magic string outside of the displayed area, starting at position 20, and read it back at certain intervals. If the display was reset by ESD, then the magic string was also erased.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 14, 2015, 12:43:50 pm
content: Probably radiation corrupting the data lines. Add shielding and grounding to the connecting header/cable and display (and PCB, if the layout is weak), or possibly try some ferrite beads (if it's on a cable).Or the same idea literally anywhere else in your circuit. Impossible to say what's vulnerable without schematic and layout.Tim

author: Kalvin
author_rank: Super Contributor
timestamp: March 14, 2015, 01:55:31 pm
content: Quote from: Niklas on March 14, 2015, 11:29:41 amClever trick!

author: sri5496
author_rank: Newbie
timestamp: March 14, 2015, 04:35:57 pm
content: Quote from: Niklas on March 14, 2015, 11:29:41 amhi thanks for the response , can you please share the code for it??
ESD issue on LCD controlled by IIC - Page 1
Forum section: electronics / projects

author: Jishnuprakash
author_rank: Newbie
timestamp: October 26, 2021, 11:57:04 am
content: hi,I work as electronics engineer, recently one of my project failed in ESD test, both is conducted and air dischargeduring ESD the LCD turns off and we had to restart entire system to make it run again,this is the first project i took over in my new company, the designing is done by an external agency who says he ishelpless in mitigating the problem with LCD, please give me any advice on how to mitigate ESD problem up to 16KVi use i2c to control the LCD which is connected to the board using 4 pin flat cable, and the screwed on to the plastic containertogether , i am providing link to the LCD device i am using (cant share main board circuit, company property)https://www.roboelements.com/product/16x2-lcd-display-with-i2c-interface/?gclid=CjwKCAjwzt6LBhBeEiwAbPGOgeMW5LfJm_8hCEwY_z1R4JyPBQ4VD9VcgQZ5Je-CEeZOhLQ7Y1g0bhoCxFgQAvD_BwE

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 26, 2021, 12:38:49 pm
content: I2C is an on-board protocol only. It is not to be used over wiring, at least not without considerable caution. As you've proved first-hand. It can be used over modest distances with differential interfaces, or isolators.Is the LCD bezel/frame exposed (subject to direct ESD strikes)?Tim

author: Jishnuprakash
author_rank: Newbie
timestamp: October 28, 2021, 10:24:16 am
content: no lcd is not subjected to direct ESD strikes

author: Jishnuprakash
author_rank: Newbie
timestamp: October 28, 2021, 10:27:09 am
content: the length of iic wire is less than 3CM

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 28, 2021, 03:08:25 pm
content: Are / could those standoffs be grounded, by any chance? (I think not, they look isolated on the LCD at least.)Adding those grounds would significantly reduce interference to the signals.Tim

author: Jishnuprakash
author_rank: Newbie
timestamp: October 29, 2021, 05:40:56 am
content: no they are not grounded, i will try grounding them, thank you for information,also if nylon or PVC Standoffs are used can we avoid this problem

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 29, 2021, 01:09:53 pm
content: Probably not, but plastic spacers could be used instead, and thru screws.You'll probably have to scrape the soldermask off nearby grounds to test it. PITA but ok for a test. Figuring out production is another matter.Tim
ESD Mats - How to bond... - Page 1
Forum section: electronics / projects

author: mrpackethead
author_rank: Super Contributor
timestamp: May 12, 2017, 08:43:48 pm
content: Im just installing new ESD mats in our fabtory, on our workbenches.. Each matt gets connected back to a common bonding point, which is also where Wrist straps get attached..Wrist straps have a 1MR resitor built into them.. Thats to 'slow' down any discharge, and also provide some current limiting if something bad happens, like something live gets in teh wrong place..What about the bonding for the ESD mat.. Shoudl it also be attached via a 1M resistor. I dont' think it should but i'm unsure..What about other bits of machinery/ equipment.. How should they be bonded down.. I'm thinking of things like a an inspection microscope, scope, sioldering irons.. Stencil printer, and pnp machines?

author: wraper
author_rank: Unknown
timestamp: May 12, 2017, 08:50:01 pm
content: Quote from: mrpackethead on May 12, 2017, 08:43:48 pmESD mat must be connected through 1M resistor. You can ground any non electrical equipment through 1M resistor as well.QuoteThose are already grounded via mains outlet.

author: azer
author_rank: Regular Contributor
timestamp: May 13, 2017, 03:14:11 pm
content: The requirements are described in ANSI/ESD S20.20https://www.physicsforums.com/attachments/ansi-esd-s20-20-2014-protection-of-electrical-devices-pdf.107997/https://www.esda.org/about-esd/esd-fundamentals/part-3-basic-esd-control-procedures-and-materials/
ESD mitigation for prototypes - Page 1
Forum section: electronics / projects

author: ivan747
author_rank: Super Contributor
timestamp: March 29, 2025, 05:24:11 pm
content: Hi everyone.I'm helping someboody with a prototype robot that to move on a PVC surface . It looks like the wheels rolling on the surface generate an outstanding amount of static electricity. I could feel it pull the hairs on my knuckles from from 10cm+ away.Anyway, two weeks ago one of the boards failed (a commercial product, not a custom board). I think it was ESD that killed it, looking back. The problem is the entire chassis is 3D printed for practicality and it's built with a Raspberry Pi and a number of HATs and other development boards. The client is iterating constantly so it doesn't make sense going custom with ESD protection at the pace we're going.What would be a good strategy?Thanks!

author: jonpaul
author_rank: Super Contributor
timestamp: March 30, 2025, 11:56:11 am
content: add a grounding strap to the robot, just like used on fuel delivery trucks.A conductive rubber strip that hangs below the vehivhej

author: Gyro
author_rank: Super Contributor
timestamp: March 30, 2025, 12:49:52 pm
content: I doubt a grounding strap is going to help much if the robot is running on a PVC surface.The first thing that comes to mind is to use PVC tyres, static builds up as a result of friction between dissimilar insulators. Apart from that, bonding the hell out of the thing, motor shafts to all circuit grounds. A layer of self adhesive copper foil on the underside of the robot as a common ground point would probably help a lot.
ESD problems --> good filter components - Page 1
Forum section: electronics / projects

author: MrMetthew
author_rank: Regular Contributor
timestamp: May 22, 2017, 04:57:04 pm
content: Hey guys,I have some problems. The situation is a test rig where dut's are plugged in with a cable. Problem is that the dut's often are charged :s. Resulting in incredible spikes everywhere in my circuits. The spikes are very short (200ns) and very high (up to 400v Vptp).Without going into to much detail there are (among other things) mosfet on those lines. The mosfets can pull these lines to the ground. These mosfets are getting destroyed by the spikes. I cant just add some capacitors to the line because it would be hard for the mosfets then to pull them to the ground reference if you know what I mean.Can you guys recommend me some good filter components for this ? They have to be extremely fast acting, see the picture of one of the captured spikes. They also need to be able to withstand a couple of hundred volts. I have problems finding something that can react fast enough. Maybe I am focusing on the datasheets to much of standard anti esd components and deeming them unworthy because of datasheet conduction speeds.I have not much experience in the subject, that's why I would really appreciate some advice!BTW: Sorry for being so vague but if I have to explain the system in detail I would be typing 2h+. I can still do that if you guys want.. Also my brain is kinda fried after 10h straight of debugging this :p

author: MrMetthew
author_rank: Regular Contributor
timestamp: May 22, 2017, 04:59:53 pm
content: image

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 22, 2017, 05:07:59 pm
content: TVS diodes are plenty fast enough, and appropriate for the job.
ESD protection - clamping diodes - Page 1
Forum section: electronics / projects

author: metRo_
author_rank: Regular Contributor
timestamp: July 16, 2014, 12:06:42 am
content: Hi,I saw a project where there is a ESD diodehttp://www.onsemi.com/pub_link/Collateral/ESD9B-D.PDFto protect from the 12v source. How does this diode works to protect against ESD? And in that case per example why should I choose the ESD9B3.3ST5G or ESD9B5.0ST5G?Thank you

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 16, 2014, 12:33:10 am
content: Er, it does what it says it does... clamps ESD?Wouldn't be a good idea from a 12V supply, they're basically 3.3 and 5.0V zeners (respectively). Wired in pairs back to back, to get the bidirectional behavior.Note that the clamp voltage is more like 10V under transient conditions -- there's no such thing as absolute "3.3V and nothing more". It wouldn't be a great idea to connect one directly across a sensitive logic input, for example, but it would be fine with a series resistor inbetween.Tim

author: metRo_
author_rank: Regular Contributor
timestamp: July 16, 2014, 08:42:22 am
content: is is the circuit where i saw it:i0.wp.com/andybrown.me.uk/wk/wp-content/images//awreflow/power_schematic.jpg

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 16, 2014, 10:03:31 pm
content: Well, it ain't gonna be 12V for long.Tim

author: metRo_
author_rank: Regular Contributor
timestamp: July 17, 2014, 12:19:52 am
content: why you said that?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 17, 2014, 02:06:32 am
content: The diode is shorting the supply above 9V or so.
ESD Protection Diode and PIC Microcontrollers - Page 1
Forum section: electronics / projects

author: PICmonster
author_rank: Regular Contributor
timestamp: May 09, 2014, 10:04:38 am
content: Dear AllI am trying to find out if ALL I/O pins on PIC24 Series or and other series for that matter have ESD protection diodes, the datasheet show these protection diodes only on the analogue port pins but does not show them for digital I/O pins so it is not clear at least to me if EDS diodes are present on digital I/O pins, I know I could test this electrically but I am looking at the datasheet to say so.Some of the voltage specs state vdd+0.3 which points in the direction of ESD diode being present but the literature does not actually say that ALL I/O pins are protected. Or have I missed something I wonder?Can anyone say for a fact ALL digital I/O have ESD protection diode based on the microchip datasheets.RegardsJim

author: dannyf
author_rank: Super Contributor
timestamp: May 09, 2014, 12:24:32 pm
content: 24F parts don't show a more detailed pin diaghram, unfortunately. The maximum voltage spec does help.Vpp pin doens't have those diodes, however.

author: bktemp
author_rank: Super Contributor
timestamp: May 09, 2014, 01:11:30 pm
content: Almost every IC has some kind of ESD protection. Normally they put a diode to Vcc on each pin, but this does not work for 5V tolerant pins. Those use some sort of zener diodes. These diodes do not limit the voltage to the absolute maximum voltage, they only break down in case of a massive ESD event. I did some tests a few years ago: I reached >15V on a 5V tolerant input pin, without much current flowing. The IC survived, but the pin I had used did change its performance. The higher voltages probably injected some charge into the input fet gates.Since that time I always add external diodes to all 5V tolerant input connected to some off board circuit.
ESD Protection: Does track length matter? - Page 1
Forum section: electronics / projects

author: Gip-Gip
author_rank: Contributor
timestamp: December 21, 2017, 08:37:33 pm
content: I'm trying to protect my circuit with a bundle of TVS diodes (Mouser #511-ESDA5V3SC6Y) and right now I have the thing sitting near center of a 1"x2" board. The tracks to the thing aren't THAT long (1" max) but for instance if a bypass cap was 1" away from a chip it wouldn't be that effective would it?Should I go for individual diodes or can it stay how it is?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 22, 2017, 02:54:35 am
content: Read the appnotes. You want it as close to the offending source, and ground, as possible. Use stitched ground plane construction. Route the signal line through the ESD diode pad, not teeing off to it. If it's a clamp diode, bypass the supply connection at the diode (or as nearby as possible; it's okay to group clamp diodes, sharing bypasses a bit).Tim

author: jbb
author_rank: Super Contributor
timestamp: December 31, 2017, 09:05:30 pm
content: If you get trouble in EMC testing, a few ohms of series resistance in the signal lines can help too.You might also want to consider whether or not you need surge protection.

author: Cervisia
author_rank: Regular Contributor
timestamp: January 01, 2018, 04:05:46 pm
content: The track between the connector and the diode might act as an antenna, i.e., ESD might create noise elsewhere.And this is a case where 90° corners can actually hurt.
ESD Protection LED driver - Page 1
Forum section: electronics / projects

author: AcHmed99
author_rank: Contributor
timestamp: July 17, 2014, 04:55:17 pm
content: I have some high powered LED’s I’ve put in a fluorescent aluminum enclosure. I’ve put together a 32W isolated flyback PFC CC driver for them and I’m going to be putting it in the existing AL enclosure that originally housed the florescent SMPS. I want to monitor the temperature of the LED’s, using Microchips MCP9701 (Active Thermistor). This means I need to bring 4 conductors out of the AL enclosure +5V, Return and the two signals from the thermistors. See attached schematic.What type of esd protection is typically used in these types of applications? I have some 330pf caps going from the input signal lines to chassis (earth) and some 5V esd diodes as well as some rectifiers for reverse clamping. Is this overkill or would it be ineffective? Any suggestions?
ESD protection of differential amplifier/op amps *TVS CHIP* - Page 1
Forum section: electronics / projects

author: ftransform
author_rank: Frequent Contributor
timestamp: March 19, 2013, 10:00:47 pm
content: So in my ohm meter circuit I thought that I could include a TVS chip. I have one of these handy and I was wondering about its operation.http://www.ti.com/lit/ds/symlink/sn75240.pdfIn the applications section it shows that there is pull-up resistors and series current limiting resistors...Will this thing work to protect a constant current source and a differential amplifier? Since its not dealing with digital logic does it really need the external resistors? Will it interfere with my measurements? Is this an inappropriate use of a USB protection chip?http://image.bayimg.com/347fe72ec1f2c03bcd5cbf0df1236a8c0ff8ffbe.jpgI'd test it but I dismantled my circuit from the breadboard, this is a list minute add on idea.My current source is op-amp based btw.

author: amspire
author_rank: Super Contributor
timestamp: March 19, 2013, 10:28:17 pm
content: The TI ESD protection chip can have a leakage current up to 1uA. If you are measuring a 10MOhm resistor with 1V applied, the current is 0.1uA and if you want the results to be better then 1%, you need less then 1nA of leakage.

author: ftransform
author_rank: Frequent Contributor
timestamp: March 19, 2013, 10:31:19 pm
content: Quote from: amspire on March 19, 2013, 10:28:17 pmah fuck I missed that. Are there better ESD protection chips? How can I protect my circuit?Perhaps a big yellow sign that says do no touch without wrist strap...

author: amspire
author_rank: Super Contributor
timestamp: March 20, 2013, 02:54:16 am
content: Quote from: ftransform on March 19, 2013, 10:31:19 pmThe solution you often see in test equipment is to use a transistor base-collector junction of a small signal transistor as a diode and a series resistor to the input terminals. It is easy to test for leakage. Get a multimeter with a 10MOhm input impedance and connect it to a 10V power supply via the diode you want to test. 1nA leakage = 10mV on the multimeter. You will probably need to add a low leakage cap across the multimeter leads, but remember the timeconstant - if you use a 1uF cap, then it takes 10 seconds to charge the cap from 0v to 10mV with the leakage current. Let the voltage settle first (the meter might have its own leakage current) and then connect the transistor. The leakage is often constant current, so the exact test voltage does not matter.I just tested a 2N2222A transistor and it was less then 10pA leakage at room temperature (leakage increases exponentially with temp from what I remember of semiconductor theory) and it can cope with a few hundred mA fault current easily.Richard.

author: ftransform
author_rank: Frequent Contributor
timestamp: March 20, 2013, 07:08:44 am
content: Quote from: amspire on March 20, 2013, 02:54:16 amexcellent I will investigate this !
ESD safe aluminium finish - Page 1
Forum section: electronics / projects

author: DanielRehak
author_rank: Contributor
timestamp: January 28, 2025, 04:07:11 pm
content: Hello,I am looking for aluminium finish that makes it ESD safe. I did not manage to find a lot of info online regarding this topic.I wonder if there is anyone who ever faced same issue - what were your solutions?

author: TimFox
author_rank: Super Contributor
timestamp: January 28, 2025, 04:17:52 pm
content: Anodizing aluminum is a problem since is a non-conductive surface that can leave gaps in the shielding.“Alodine(TM)” or “Iridite” finishes are not conductive, but are thin enough that metal-to-metal contact breaks through to get reasonable electrical connection. They are more likely to wear, however, than good anodized finishes.

author: DanielRehak
author_rank: Contributor
timestamp: January 31, 2025, 03:58:14 pm
content: I contacted multiple aluminium parts manufacturers and it looks like there really does not exist such a technology.I would expect there to be some e.g. powder coating finish that provides ESD safe layer to aluminium.Guess we will have to think about a different way how to handle heat dissipation and at the same time dont destroy our device.
ESD safe caps in series still ESD safe? - Page 1
Forum section: electronics / projects

author: MrMetthew
author_rank: Regular Contributor
timestamp: April 25, 2018, 03:50:55 pm
content: Hi all,I was wondering, if I put two esd safe capacitors (e.g. AVX ESD55C472K4T2A-18) in series to double the voltage rating of the cap, will they preserve their esd safe properties?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 25, 2018, 05:51:35 pm
content: I don't see why not.Tim

author: MrMetthew
author_rank: Regular Contributor
timestamp: April 26, 2018, 07:53:50 am
content: Quote from: T3sl4co1l on April 25, 2018, 05:51:35 pmMaybe because the esr gets doubled? I am not sure..

author: jmelson
author_rank: Super Contributor
timestamp: April 26, 2018, 07:41:12 pm
content: Quote from: MrMetthew on April 25, 2018, 03:50:55 pmThat's 4700 pF? Geez, what's this ESD safe stuff? I think it would be VERY hard to damage a 4700 pF cap unless your ESD conditions are so bad you are getting visible/audible sparks jumping around. The really worst-case human body model has a 470 pF reservoir cap that is charged to the test voltage, this is worse than almost any real ESD event you can imagine in a station where exposed PC boards are handled.Jon

author: Niklas
author_rank: Frequent Contributor
timestamp: April 26, 2018, 09:33:00 pm
content: The internal structure is slightly different on these capacitors to provide a discharge path that bypasses the wanted capacitance. Apart from that they are just like normal capacitors and can be connected in series or in parallell.https://incompliancemag.com/article/effectiveness-of-multilayer-ceramic-capacitors-for-electrostatic-discharge-protection/

author: wraper
author_rank: Unknown
timestamp: April 26, 2018, 10:07:09 pm
content: Quote from: Niklas on April 26, 2018, 09:33:00 pmThey don't provide any discharge path. The difference is in placement of conductive plates.
"esd safe" insulating material? - Page 1
Forum section: electronics / projects

author: jeremy
author_rank: Super Contributor
timestamp: March 19, 2019, 11:00:13 am
content: Hi,I often have this problem, but don't know the proper answer to it, so I was hoping that someone could point me in the right direction.I have a bare PCB which is being tested on an ESD mat. However, it seems that due to the conductivity of the ESD mat, there is some slight leakage which is affecting the measurements (I think...). What is a good material to put between the ESD mat and the PCB to insulate the two from eachother? Ideally, I'd like to put something like a 2mm thick piece of acrylic, but I know that acrylic is very good at holding static charge, so that's probably not a good idea

author: Siwastaja
author_rank: Super Contributor
timestamp: March 19, 2019, 01:49:17 pm
content: I would consider the pink "static dissipative" ESD bags for this purpose.These bags are used to package ESD sensitive components inside their ESD shielding packs - the idea is, while they won't protect the components from ESD shocks (hence, external ESD control, like the ESD pack, or in your use case, your ESD mat, is needed), they won't generate charge themselves too easily.

author: Gyro
author_rank: Super Contributor
timestamp: March 19, 2019, 01:50:12 pm
content: It's pretty hard to build up a significant charge on cardboard.

author: LukeW
author_rank: Frequent Contributor
timestamp: March 20, 2019, 05:05:13 am
content: I think what you're asking for is intrinsically impossible.Any good insulator will allow charge accumulation, and any ESD-dissipative material must be at least slightly conductive.You have to find the right balance, the right tradeoff in the resistivity of the material, for your application.

author: helius
author_rank: Super Contributor
timestamp: March 20, 2019, 06:15:21 am
content: Does your board have any mounting holes? Try elevating it above the mat using metal standoffs. That will provide a path for static charges to pass to ground (via the mat) but not load any sensitive nodes on the board.

author: jeremy
author_rank: Super Contributor
timestamp: March 20, 2019, 06:22:00 am
content: Thanks for the replies.helius: In this case, no, but I am looking for a general solutionLukeW, anti-static materials do exist that are not conductive, they just resist charge buildup using via the triboelectric effect. This is the main difference between "anti-static" and "static dissipative" materials.Gyro: thanks, I will have to look into this. I was thinking paper or something similar might workSiwastaja: Actually, I'm using those blue digikey bags right now. Also that pink foam that stuff sometimes gets shipped in. I just don't know where I can get large pieces of it (say, A3 or A4) without just trying to buy the largest item I can find at digikey...PS fun fact: I ordered a TI book from digikey once (as in made of paper), and it came double bagged in static dissipative and anti static bags