hybridfree/eevblog-posts huggingface dataset:
Capacitive Battery Chargers - Page 1
Forum section: electronics / beginners

author: FiveseveN
author_rank: Newbie
timestamp: December 01, 2012, 02:43:12 pm
content: If this topic has been covered before I apologise. And if that's the case, could you suggest some search terms? My initial search didn't lead me to an answer, hence the following:A recent post on HaD led me to this (sketchy) project page:http://screwdecaf.cx/dapimp.htmlI've only dabbled in small-signal audio and some basic automation and had never encountered the concept of capacitive charging before, not pertaining to wireless power transfer, anyway. What goes on inside a rechargeable battery is still a mystery to me, so I can't dismiss the idea out of hand. But if it's so simple and cheap to construct a self-regulating charger, why isn't everybody and their dog using one (besides the safety issues)? Would such a design work reliably? Within what limits? And how could it be improved?Thanks.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 01, 2012, 04:10:05 pm
content: There is NO regulation!The AC is directly connected to the output (via fuse and bridge rectifier)!This thing will kill your batteries and yourself, not necessarily in that order!

author: amyk
author_rank: Super Contributor
timestamp: December 02, 2012, 09:27:53 am
content: You almost answered your own question. According to the not-a-schematic, it's a standard capacitive dropper supply connected directly to a battery...The capacitors are not even X-rated.

author: FiveseveN
author_rank: Newbie
timestamp: December 02, 2012, 02:23:18 pm
content: Quote from: amyk on December 02, 2012, 09:27:53 amYeah, that was an obvious red flag, though it's an easy fix. Now that I found more info on cap dropper supplies it's all starting to come together. Thanks, guys!

author: PA4TIM
author_rank: Super Contributor
timestamp: December 02, 2012, 10:59:24 pm
content: Dangerous toy. Only the Rin of the battery limmits the voltage, the not for his use type caps limmit he current. A sort of zapper but using a voltage instead of a current. I use sometimes a charged cap to bring a nicad back to live but most times it is only for a short time. You burn away a short but other cristals that are allmost causing a short stay.It also has nothing to do with desulfating, he uses spikes but only for a short time. I'm doing a test with a desulfator I made out of curiousity and it is now connected for 3 months to a very sulfated battery. ( from self discharging during a long periode) I was not able to charge it. I measured the complex impedance then and did a load test. After 2 months it was indeed much better but still way from what it ever was ( i bought an identical new one and measured that too)So if desulfating with 3A pulses around 100V ( low dutycycle) after 3 months only makes it usable to charge a telephone or burn some led lights then his devise will not save any battery.It will load them, but in a very crude and dangerous way.
Capacitive Coupling Noise Equation - Page 1
Forum section: electronics / beginners

author: Camelkos
author_rank: Newbie
timestamp: September 29, 2020, 09:07:45 pm
content: Hi Everybody,Can someone please explain how we get this equation, frome this circuit thank you very much!!

author: drdm
author_rank: Contributor
timestamp: September 30, 2020, 01:55:36 pm
content: C1Gdoes not play any role since it is connected directly to an ideal voltage source.The rest of the components form a voltage divider. Upper part of the divider is C12. The lower part is the parallel of C2Gand R.If you represent R by ZRand 1/jwC with ZCyou will have:Vn=Vi(Zr//Zc2g)/((Zr//Zc2g)+Zc12)The rest is a page of algebra which I'll leave to you.

author: Camelkos
author_rank: Newbie
timestamp: September 30, 2020, 09:27:31 pm
content: i think there's something wrong in what you wrote, can you please correct the equation

author: drdm
author_rank: Contributor
timestamp: October 01, 2020, 08:18:28 am
content: Here you have the complete solution.It could be shorter, I suppose.

author: Camelkos
author_rank: Newbie
timestamp: October 01, 2020, 08:39:35 am
content: Thank you very Much !!
Capacitive discharge spot welder's SCR. How does this work? - Page 1
Forum section: electronics / beginners

author: beelzebozo
author_rank: Newbie
timestamp: September 18, 2017, 07:22:56 pm
content: I was looking at this video:.He seems to have his power source turned on the whole time. What I couldn't quite get is why the SCR seems to stop conducting while it is still hooked to his power supply - I thought that once it starts conducting it wouldn't stop.His other video shows basically the same thing - power source hooked up and no indication he switches it off between welds - and yet the SCR seems to stop once the caps have discharged.I'm obviously missing something, can you help me figure it out?

author: SeanB
author_rank: Super Contributor
timestamp: September 18, 2017, 08:16:59 pm
content: Power supply has current limiting, and the maximum current it can supply when short circuited is below the holding current of the SCR he is using, so after the pulse the SCR will turn off, allowing the power supply to slowly charge up the 1F capacitor again for the next shot.

author: beelzebozo
author_rank: Newbie
timestamp: September 18, 2017, 09:09:33 pm
content: Quote from: SeanB on September 18, 2017, 08:16:59 pmThis was basically my one and only guess. He stated in one video that he's charging with 3 amps, and in another that it's just under an amp, which seems way over the holding current, and that threw me off. TheSCR's holding current seems to be around 150mAmp, not sure what to make of it...Regarding charging - "we are doing three amps"https://youtu.be/u6-HpR7Wfr8?t=43"Just under an amp":https://www.youtube.com/watch?v=OtCiorlYP1U&feature=youtu.be&t=700

author: BrianHG
author_rank: Super Contributor
timestamp: September 19, 2017, 10:21:01 am
content: A guess:Remember, those contacts are held in place by hand in both videos. I bet if the probes were mechanically secure spring loaded onto the strip to the battery, the SCR would stay on longer further discharging the cap & generate a stronger weld.From what I see, I doubt that the capacitor is fully emptied below 1v after a weld. A 1F cap should do a lot more damage. I bet it's just the poor contact through the surge of current with hand held probes, and, once the gate of the SCR is off and there is an open moment in the load on the probes, SCR will unlock to off.
capacitive moisture sensor ground loops - Page 1
Forum section: electronics / beginners

author: Cichero_Gabriel
author_rank: Newbie
timestamp: April 05, 2023, 02:18:36 pm
content: Dear,I'm working in a automated irrigation system for plants, using:-Arduino pro mini as MCU-Capacitive moisture sensor V2 (uses a 555 oscilator)-12v PSUi'm facing some ground loop interference when the sensor is on a flower pot sit on the ground.The code simply (don't need to share): do lectures of the soil, when the lectures are below a treshold, irrigate water through a pump. When the soil gets enough moisture, the pump stomp.In my testings in a flower pot (soil containded), when the pot is elevated from ground, the readings are Solid and everything go just fine.BUT, when the pot is on the ground, i'm receiving crazy oscilatting lectures that are imposible to manage (only doing hard filtering by software: averages, hysteresis, etc). The preliminar solution is to put a plate below the pot, this improves the readings, but not as good as i need.There is any solution to this situation?FYI: i filterd the power line with decoupling caps, added a pair of inductors and 100nf caps, flying diode for the motors. But this are not part of the problem that i'm facing.

author: floobydust
author_rank: Super Contributor
timestamp: April 05, 2023, 04:04:33 pm
content: Welcome to the forumsOne cause of your problem can be the 12V power supply. If it is SMPS and two-prong (no PE ground) mains- then the whole circuit will float above earth-ground potential with a lot of noise. The is due to the Y-capacitor. I would add a wire ground connection from DC GND to PE ground. Or the ground connection could be made with a capacitor+resistor, like 0.1uF 1MEG if you want the system floating at low frequencies (DC) to prevent corrosion on the probe.You can prove it by measuring the noise with a multimeter on ACV between Arduino GND and PE ground. Or run the Arduino from a battery just to do a test.The motor can make noise as well. This will give bad moisture readings only when the pump motor is running. Usually 3 ceramic caps, one across brushes and from (+) and (-) to motor case as well, like 0.1uF will help greatly.Otherwise, I would say the soil moisture sensor is not a good design. There are many cheap ones out there that work only in the lab.
capacitive touch switches  - Page 1
Forum section: electronics / beginners

author: franksterb92
author_rank: Contributor
timestamp: November 24, 2020, 08:19:58 pm
content: hey I'm designing a front panel for a project and was wanting to know if anyone knew of a manufacturer that will make a pcb with capacitive switches with a silk screen over them to show the buttons function thanks for the help

author: JustMeHere
author_rank: Frequent Contributor
timestamp: November 25, 2020, 12:54:54 am
content: Every PBC manufacturer will do this. All you need is traces.https://electronics.stackexchange.com/questions/281921/pcb-touch-button

author: franksterb92
author_rank: Contributor
timestamp: November 25, 2020, 09:11:22 am
content: thank you im kind of new to this getting stuff manufactured i found an example project in kicad if anyone is interestedhttps://github.com/jspark311/SX8634-Breakout
Capacitive Touch Toggle Switch AT42QT1012 - Page 1
Forum section: electronics / beginners

author: dteck
author_rank: Contributor
timestamp: June 10, 2015, 06:43:08 pm
content: Hi everyone,I'm having a bit of a problem with what I thought was a simple enough design. I was trying to make a on/off toggle switch using the Atmel qt1012 touch sensor. I did a quick layout of a board and used OSH Park to get it made. Everything seemed fine. I put one together and it seemed to work You would touch the "pad" pin and the LED output indicator would light up and the NMOS would conduct. And then in my stupidity I fed it too much voltage. The max rating it 6.5v and I had ramped it up to 12vThat was just a careless mistake on my part. I put the board away and didn't think about it for a while.Yesterday I pulled one out and planned to use it as part of another project. I just wanted a nice on/off switch for a 5v project. I soldered all the components on and got nothing. or so I thought. When I gave it 5v the QT1012 got super hot. So I thought maybe I shorted something out. So I double and triple check my soldering look for bridges and shorts, use a multimeter and check continuity etc. desolderd and resoldered the chip. Give it 5v again and still no output but overheats like crazy. So I say fine maybe its a bad chip, maybe I overheated it in soldering, whatever. I decided Ill swap it out for my last qt1012. I put that one on the board and it does nothing. It doesn't overheat but it also doesn't do anything at all.I used a multimeter to check voltages and it was getting 5v. but there was no output, no voltage on the sensing line, nothing. I thought maybe it was because I was using a cheap meter. So I pulled out a scope. It showed power going into the chip and nothing coming out. nothing on the output and nothing on the sense line.I guess its possible I got some bad chips but I was hoping I could ask you guys to look over my design and tell me if I'm doing something stupid that is destroying these chips.Datasheet for the qt1012 (AT42QT1012-TSHRCT-ND)http://www.atmel.com/Images/Atmel-9543-AT42-QTouch-BSW-AT42QT1012_Datasheet.pdfDatasheet for the nmos (785-1581-1-ND)http://aosmd.com/res/data_sheets/AON7410.pdf

author: Fredled
author_rank: Newbie
timestamp: September 20, 2019, 07:38:49 pm
content: The AT42QT1012 is a very unreliable piece of crap.First of all, it works only in 3V, not in 5V as written in the datasheet.It's also hyper sensitive to interferences, changes in the environement. very difficult to set up.Two or more devices on the same PCB won't work reliably.
Capacitode??? - Page 1
Forum section: electronics / beginners

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: January 12, 2023, 12:42:26 am
content: Just pulled two disc cermic caps from the 14 V power input to a radio. Someone added them, not originsl.They tested as diodes on two testers.One with 1.3 and the other with 1.8 volts drop.Green, 1.2 cm dia discs.1M16VY5SMexicoAny Ideas???

author: Psi
author_rank: Super Contributor
timestamp: January 12, 2023, 01:09:46 am
content: maybe its actually a 12V radio and they were running it from 14V so needed some voltage drop

author: BillyO
author_rank: Super Contributor
timestamp: January 12, 2023, 01:25:06 am
content: Perhaps they were varactors.

author: bdunham7
author_rank: Super Contributor
timestamp: January 12, 2023, 01:49:27 am
content: That's a pretty bad choice for that application--a 16 volt MLCC on a 14 volt (automotive?) supply. Y5S is perovskite, perhaps it can leak asymmetrically somehow or perhaps it has more complex reaction to your testers test signal. What do they measure with a DMM on resistance or diode check?https://iopscience.iop.org/article/10.7567/JJAPS.24S2.1027Replace them with something reasonable, or leave them out if they aren't needed.

author: golden_labels
author_rank: Super Contributor
timestamp: January 12, 2023, 01:59:02 am
content: Markings suggest a ceramic capacitor. Y5S indicates properties of the dielectric used.Testers guess the type of an element from various electric properties. They are not foolproof. No real component exhibits properties of just a single ideal element and misidentification is possible.It will be hard to tell, what is their purpose, without knowing the circuit. Show clear photos, provide some details of the circuit.Alternatively it may be a varistor with uncommon markings.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: January 12, 2023, 02:05:39 am
content: They are unnecessary, Additional filtering added.They check as diodes on my Fluke also.Radio works better without themI think they are damaged caps but have never seeen this particluar result.Caps with these markings are seen in other radios I have worked on.Just thought it was interesting.

author: bdunham7
author_rank: Super Contributor
timestamp: January 12, 2023, 02:18:53 am
content: Quote from: Wallace Gasiewicz on January 12, 2023, 02:05:39 amI've seen various strange leakage characteristics before, but they typically either go away or short entirely by the time you get them desoldered and pulled out. It would be interesting to fully characterize your 'diodes', but I suspect any serious testing would cause them to change.

author: golden_labels
author_rank: Super Contributor
timestamp: January 12, 2023, 03:38:47 am
content: Can you attach photos of the components in question? Can you show, where they were added? That would really help.I can’t imagine, what failure mode in a ceramic capacitor could be asymmetric. And not in one, but two components.
Capacitor  - Page 1
Forum section: electronics / beginners

author: jeewantha
author_rank: Newbie
timestamp: August 21, 2018, 01:09:45 pm
content: why use capacitor like this?

author: Dave_C
author_rank: Contributor
timestamp: August 21, 2018, 01:32:44 pm
content: I have no idea why anyone would do that.I've noticed vias at the edge of the board (added red arrows) so it might suggest some RF wizz-bang that I'm not aware of.

author: Shock
author_rank: Super Contributor
timestamp: August 21, 2018, 01:39:22 pm
content: Spares or for a onboard configurable circuit somewhere is my guess. Not that they are the same size but see what looks like a zero ohm resistor to the left next to those empty pads.

author: jeewantha
author_rank: Newbie
timestamp: August 21, 2018, 02:00:22 pm
content: I see this type caps in Samsung & Huawei mobile phones.Mostly have in Huawei.

author: glarsson
author_rank: Frequent Contributor
timestamp: August 21, 2018, 02:10:12 pm
content: Related to this thread?https://www.eevblog.com/forum/chat/whos-eating-all-the-100nf-0603-caps/

author: jeewantha
author_rank: Newbie
timestamp: August 21, 2018, 02:12:59 pm
content: link not working

author: glarsson
author_rank: Frequent Contributor
timestamp: August 21, 2018, 02:26:11 pm
content: Fixed. Forum requires trailing / that was lost during copy-paste.

author: jeewantha
author_rank: Newbie
timestamp: August 21, 2018, 02:30:23 pm
content: No.

author: glarsson
author_rank: Frequent Contributor
timestamp: August 21, 2018, 02:40:31 pm
content: No what? Trailing slash or still not working?

author: jeewantha
author_rank: Newbie
timestamp: August 21, 2018, 02:57:54 pm
content: sorry. link is working. Not related

author: glarsson
author_rank: Frequent Contributor
timestamp: August 21, 2018, 04:53:25 pm
content: If a lot of extra capacitors without purpose are used then there will not be enough of them. :-)

author: David Hess
author_rank: Super Contributor
timestamp: August 21, 2018, 05:39:39 pm
content: It looks like a layout mistake to me but if those capacitors were between power planes, there would be a massive short.
Capacitor? - Page 1
Forum section: electronics / beginners

author: vidarr
author_rank: Frequent Contributor
timestamp: March 23, 2019, 06:28:16 pm
content: Hey guys. Does anyone know what this is in this picture? Is it a capacitor?Thanks!

author: The Soulman
author_rank: Super Contributor
timestamp: March 23, 2019, 06:48:59 pm
content: A eraser with a piece of wire shoved thru.You are a week early.

author: ebastler
author_rank: Super Contributor
timestamp: March 23, 2019, 06:53:10 pm
content: Bored in class?

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 23, 2019, 07:09:50 pm
content: Quote from: The Soulman on March 23, 2019, 06:48:59 pmThe piece of wire that once was a paperclip.

author: vidarr
author_rank: Frequent Contributor
timestamp: March 23, 2019, 07:38:54 pm
content: Ah, I see it now. Duh. I need glasses.
Capacitor aging questions, should i Replace this MLCC to another type? - Page 1
Forum section: electronics / beginners

author: alexg
author_rank: Regular Contributor
timestamp: February 19, 2018, 04:02:11 pm
content: Hi All, simple practical question:I have a simplest circuit in which I feel mic output into opamp and then into microcontroller to sample output with ADCthe schematic for mic part is as simple as this example, except my capacitor and resistor value is different.I chose the capacitor to be ceramic, package size 0402 to keep it small and everything works just fine, however because that capacitor and opamp resistors form a high pass filter I chose capacitor value to be very specific - 9nF, (X5R type)I read that ceramic capacitors have aging effect and I have concern that overtime that 9nF capacitance will change and circuit won't operate as desired, however as I said so far everything works just fine.My question is, should I be concerned about aging effect, will if affect this value much? I know what C0G (NP0) type capacitors do not have aging effect, but unfortunately for me they start at 0805 and I wanted to keep things as small as possible so I am trying to avoid that, however I can go for 0805 if absolutely necessary. What would you recommend?Thanks.

author: Jwillis
author_rank: Super Contributor
timestamp: February 20, 2018, 11:32:19 am
content: I have tested ceramics from the 1930s and all come within spec.So I would say no you don't need to worry about aging effect.Really old electrolytics and really old wax yes.They do dry out.

author: alexg
author_rank: Regular Contributor
timestamp: February 22, 2018, 12:43:40 am
content: Quote from: Jwillis on February 20, 2018, 11:32:19 amThank you for reply, for last day I been studying variety of capacitors that are available to order and it seems that X7R have a bit better aging characteristics comparing to X5R plus I am ordering "high reliability" series from TDK so that should provide some peace of mind.

author: ovnr
author_rank: Frequent Contributor
timestamp: February 22, 2018, 01:09:51 am
content: I really wouldn't worry about aging, especially for this sort of application with no self-heating or losses. A DC/DC going full tilt with multiple amps of ripple current, sitting at 80-90 deg C 24/7? Might be iffy. This is pretty much as far as you can get from that.Also, you can get 0603 C0G/NP0 caps up to 18n. You don't have to jump straight to an 0805.
Capacitor behavior in the circuit - Bypass Capacitor - Page 1
Forum section: electronics / beginners

author: Apeksha
author_rank: Newbie
timestamp: March 09, 2019, 04:16:00 pm
content: I am trying to measure the supply current of a CAN transceiver during fault conditions, one thing which I noticed was that during CANH to GND(when the current consumption is supposed to be the highest), the current was kind of like a sine wave and going negative during '1' bit transmission(recessive state). Below is the circuit,R410 was unmounted and current was measured at Vcc. When I unmounted the bypass capacitor C405 (470nF), I noticed that the current waveform as expected, as in was not going negative during '1' bit trasmission.Waveform with capacitor :The yellow and pink signals are CANH and CANL signals, the green is the TXD signal from the function generator, the blue signal is the current signal and the last signal is the 'CANH-CANL' difference signal.Waveform without capacitor:The green is the current signal, blue is the CANH signal, pink and blue are RXD and TXD signals respectively.I understand that the capacitor was trying to filter and hence the waveform was not a square waveform, but could someone please elaborate , I'm trying to understand why the current is going negative ? (the CAN transceiver is being powered by a 5V regulator, CAN supply current going negative means that the current is being sinked to the 5V regulator ?Is that possible? or is the current flowing through the output capacitor of the 5V regulator be a possibility?)
Capacitor blew up, what did I do wrong? - Page 1
Forum section: electronics / beginners

author: ra-ma
author_rank: Contributor
timestamp: April 24, 2018, 08:11:17 pm
content: Hi, in this link I described my new function generator and an issue I do have in regards to peaks:https://www.eevblog.com/forum/testgear/exact-electronics-model-119-function-generator-looking-for-schematicdocu/msg1478541/#msg1478541While measuring today with the oscilloscope I found that the spikes are also in the +/- 15 volts internal supply, in the timing absolutely parallel to the spikes in the curve. Therefore I decided to replace the existing capacitors by new ones as the whole machine is some decades old. I couldn't see fluid leakage or measure a short circuit or much too high/low capacitance but whatsoverer changed the caps.When turning on the function generator after the change, everything looked fine. +/- 15 volts were available and also the spikes seemed to be much less than before. But during my further measurements after a couple of minutes - a big boom - and one of the capacitors blew.What did I do wrong? Yes, the new capacitors have a higher capacitance, but voltage fits and I'm very sure that polarity was ok too. Any hints?

author: janoc
author_rank: Super Contributor
timestamp: April 24, 2018, 08:14:26 pm
content: Are you really really sure about the polarity? Because this is exactly what happens when you solder in the electrolytic cap the wrong way around, especially when it happened shortly after powering the device up.

author: cvanc
author_rank: Frequent Contributor
timestamp: April 24, 2018, 08:34:47 pm
content: Agreed; what happened is the classic reversed polarity failure mode.

author: ra-ma
author_rank: Contributor
timestamp: April 24, 2018, 08:36:36 pm
content: OK, thanks. I'll try it tomorrow again and check also the other capacitors for correct polarity.

author: james_s
author_rank: Super Contributor
timestamp: April 24, 2018, 11:41:31 pm
content: One thing to watch out for is that silkscreen errors are not terribly uncommon. I have worked on several devices where the printing showed the wrong polarity. If in doubt follow the circuit.

author: wraper
author_rank: Unknown
timestamp: April 25, 2018, 12:34:36 am
content: Nice fake Sanyo capacitor. Dunno if you soldered it in reverse or it was mislabeled but never buy capacitors on ebay, aliexpress or DX. FYI Sanyo branded capacitors are not made since around 8 years ago. They are called SUNCON now, and Sanyo/SUNCON don't have X style vent.

author: cvanc
author_rank: Frequent Contributor
timestamp: April 25, 2018, 01:59:49 am
content: (squints at photos again) Yeah, probably a fake capacitor... note also the strange coppery colored leads. Weird.And I can 2nd the idea of incorrect silkscreening on a PC board, I've seen that too.

author: Nerull
author_rank: Frequent Contributor
timestamp: April 25, 2018, 02:38:50 am
content: The Amiga CD32 came from the factory with not only reversed silkscreen, but reversed capacitors too.
Capacitor codes like PEI, CL11, CL21, CBB, etc. - Page 1
Forum section: electronics / beginners

author: Lee Leduc
author_rank: Regular Contributor
timestamp: May 27, 2016, 02:36:16 pm
content: I'm looking at film capacitors and see codes like PEI, CL11, CL21, CBB, etc. It looks like these codes describe the type and construction of the capacitor. Are these codes an industry standard or does each manufacture have their own set of codes? Can anyone point me to a document or webpage that explains these codes?Thank you.
Capacitor damaged? - Page 1
Forum section: electronics / beginners

author: raiju
author_rank: Newbie
timestamp: May 27, 2017, 02:46:26 pm
content: Hi,I noticed a kink in the housing of one of the capacitors, it is from a (new) gpu, card works fine. Can someone with experience please tell me if it is damaged or purely a cosmetic thing.Thank you

author: Seekonk
author_rank: Super Contributor
timestamp: May 27, 2017, 02:54:52 pm
content: Jim Lewis says that if you even drop an electrolytic capacitor on the floor, you shouldn't use it. Practically, I've had caps with major dents that have run for years.

author: raiju
author_rank: Newbie
timestamp: May 27, 2017, 02:59:14 pm
content: Quote from: Seekonk on May 27, 2017, 02:54:52 pmThe card is in a passively cooled system, I am going to do one final mount and then don't want to touch it again for at least 5 years. If I were to replace them am I correct in assuming it is a 2.5v 820µF cap?

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: May 27, 2017, 11:21:46 pm
content: If the card is working, leave it be. Given that the PCB is likely a 8+ multilayer, you might damage the board trying to desolder this cap. Not worth taking the risk IMHO.
Capacitor Dielectric for PLL LP filter? - Page 1
Forum section: electronics / beginners

author: ssashton
author_rank: Frequent Contributor
timestamp: October 27, 2020, 06:25:55 pm
content: I'm designing a board that has a AD1401 audio DSP chip on board. The datasheet specifies a PLL LP filter that includes a 56nF capacitor.I have read that PLL filters tend to use class-1 dielectrics, but it's pretty hard to find a 56nF C0G or U2J 0805 or 0603. They do exist but are expensive (and out of stock at my preferred supplier).How critical is it to use class-1 dielectrics for such a filter?It seems to be Analog Devices would not have designed an IC around using a rather scarce part value.

author: Vovk_Z
author_rank: Super Contributor
timestamp: October 27, 2020, 07:31:41 pm
content: What if 47nF plus 10nF in parallel? Those ones are more popular and obtaimable.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 27, 2020, 08:48:41 pm
content: The text says +-20% tolerance for the capacitors. So 47 nF would still be OK if not too high tolerance (e.g. more than 10%). If in doubt have a 2nd FP, but I doubt it would be needed. For a single, home build unit one may just stack 2 capacitors if needed.X7R or similar have quite some temperature effect and can react to mechanical stress. For a sensitive use this may be too much, though I doubt one would hear it.

author: ssashton
author_rank: Frequent Contributor
timestamp: October 27, 2020, 09:26:47 pm
content: I'm going to have 100-200 made with pick n place. So doing it by hand is not desirable.Even 47nF is not that common in class-1, I think it is simply a large value for SMD. U2J is all I can find actually, no C0G/NP0.I'll probably parallel 47nF and 10nF. It's a squeeze in my current layout thoughAlternatively I could do a though hole poly-film part.Anyway, the main point was me wondering if X7R would be okay, and it seems probably not a good idea.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 29, 2020, 08:19:52 am
content: It depends on the application if X7R can be tolerated. PLLs are used with very different demands on the precision. So it can be OK, but it would add some noise and tolerance to the capacitance.Going from 56 nF to 47 nF would probably be no issue. 47 nF C0G are not that rare (size 0805), though no longer as cheap as X7R.
Capacitor discharge indicator  - Page 1
Forum section: electronics / beginners

author: perfect_disturbance
author_rank: Regular Contributor
timestamp: September 17, 2012, 11:53:33 pm
content: I just got a new Agilent u1242b and today I noticed an indicator flashing on the screen in uA mode that I didn't understand. I looked it up and its the capacitor discharge indicator but it didn't say what it means anyone know?

author: perfect_disturbance
author_rank: Regular Contributor
timestamp: September 22, 2012, 06:36:05 pm
content: So from the lack of responses this is either super obscure and no one knows. Or super obvious and everyone is face palming because I'm so dense. Which is it?

author: Amarbir[Lynx-India]
author_rank: Frequent Contributor
timestamp: September 22, 2012, 07:34:08 pm
content: Well Buddy ,My U1242A Is Comming If It has this i will surely investigate the same .Lets see what you are talking about .BTW on eevblog never come to conclusion i am a dealer but many people kick my ass in electronics here ,Cos they are far more experienced then me here .So let some veteran see your post hang on a bit
Capacitor Equations - Page 1
Forum section: electronics / beginners

author: mikec
author_rank: Contributor
timestamp: May 18, 2013, 11:21:03 pm
content: Hi,I have a simulation/scenario where I can't use the standard capacitor equations to find the capacitor voltage or current while charging. I have run the simulation in LTSpice and the basic scenario is where the risetime of the pulse signal is much slower the time constant (RC) of the circuit. I have attached the circuit and the plot. I had never noticed this before as any graphs show an ideal very fast risetime for a pulse and basically I do the same when I am normally simulating. Must literature explaining capacitors deal with 2 scenarios where the pulse length is either 1. Shorter than the time constant or 2. Longer than the time constant but I have never seen the risetime been considered.The first thing I note from the plot is the maximum charge current that is reached which is only 1mA, now I know that I=C x dv/dt so because the rate of change of voltage is "slow" the circuit never reaches the max current in the circuit which as a rule of thumb I use I=V/R = 1V/100 = 10mA in this case. I know when I decrease the risetime of the pulse to be much faster than the time constant I get about 10mA.The other thing I note is that the equation Vcap = Vsource(1-e(-t/RC)) doesn't hold for the first portion of the graph (in the orange box), again this clear because Vsource has not reached its max or final value.The third thing I note is that at the very start after applying Vsource the Vcap is exponential which gives rise to an exponential Icap, after this the rate of change of Vcap seems to follow Vsource. I can't explain this part of the graph?What I'd like to know is are there equations for this scenario that can be used to calculate say Vcap when the rise time of the pulse is longer than the RC?What a practical consequences of this when designing a circuit? Has or does anyone frequently consider this when designing a circuit?Cheers!
Capacitor ESR - Page 1
Forum section: electronics / beginners

author: edmundopt
author_rank: Regular Contributor
timestamp: December 15, 2014, 03:18:24 pm
content: Hello, I have some nichicon caps on a SMPS, wich works about 50..60khz, I took them out and measure them with the ESR meter ( a DE-5000 ) , problem is, nichicon datasheet does not mentions the ESR value, so I have no reference value.I have attached the datasheet of the capacitor series.The question is, how to calculate an aproximate value of the ESR with the values of the datasheet.I went to search and found very long math formulas but I kind allways miss one or two values on them to get the ESR.Can someone help on the 220uf 50v 10x2.5mm capacitor?

author: JoeO
author_rank: Frequent Contributor
timestamp: December 15, 2014, 03:23:00 pm
content: What are you reading for the ESR value?

author: wraper
author_rank: Unknown
timestamp: December 15, 2014, 03:25:09 pm
content: It will be OK if below 0.3 ohm on 100khz range.

author: Wytnucls
author_rank: Super Contributor
timestamp: December 15, 2014, 08:03:31 pm
content: Why did you buy an expensive LCR meter if you don't know how to use it?Most electrolytic capacitors are characterized for tan d at 120 Hz. Yours is no exception and your meter can measure it very easily.There is no need to work out the ESR.Tan d above 0.12 means your cap is bad.

author: edmundopt
author_rank: Regular Contributor
timestamp: December 16, 2014, 05:47:26 pm
content: Wytnucls, thanks for the answer:I think you can help me with this:dissipation factor = tan d(delta)so, tan d = ESR / |XC|, where XC = 1 / 2 * pi * f * Cso XC is frequency and Capacitance dependentand tan d is given in the datasheetso ESR = tand d * XCI have found a nichicon 0.1uf on my stock and done some calculations with good results, I used the same tan d value for 120hz and 1khz.So I think I can go to "the store next door" and measure some replacement caps.btw, deer DE-5000 is near 100€ and not accurate bad model is 60€ so....
Capacitor identification - Page 1
Forum section: electronics / beginners

author: ghorizo
author_rank: Contributor
timestamp: November 01, 2021, 11:16:58 am
content: Hi I got this burnt cap I can't find info about. Is it just an aluminum cap?Edit: this is AC and there seems to be none available with these specs. Could it be a film capacitor?

author: drdm
author_rank: Contributor
timestamp: November 01, 2021, 12:07:29 pm
content: It looks like a simple aluminum cap.

author: wraper
author_rank: Unknown
timestamp: November 01, 2021, 12:18:47 pm
content: 250V rating seems to be AC. Is it connected across mains voltage? IMHO using 0.1uF X2 safety film capacitor as replacement is appropriate.

author: ghorizo
author_rank: Contributor
timestamp: November 01, 2021, 12:22:13 pm
content: Yes it's wired after the switch in an old power drill, I suppose for noise suppression from the motor.I actually have an mp3-x2 0.1uF 275V, it should still be ok right?

author: wraper
author_rank: Unknown
timestamp: November 01, 2021, 12:38:24 pm
content: Quote from: ghorizo on November 01, 2021, 12:22:13 pmYes

author: ghorizo
author_rank: Contributor
timestamp: November 01, 2021, 12:48:42 pm
content: Great, thank you for helping out!

author: NorthernWing
author_rank: Contributor
timestamp: November 01, 2021, 02:56:00 pm
content: ^Yep, that's almost definitely some kind of metallized film capacitor from SCR in France (now Cefem Group). If it's across mains AC, put an X2-rated film cap of similar rating in there and you'll be fine.
Capacitor identification and what to use?  - Page 1
Forum section: electronics / beginners

author: Crambone
author_rank: Frequent Contributor
timestamp: July 05, 2024, 09:58:13 pm
content: I need to replace a SMD capacitor labeled on schematic as 103P. I’m just not sure where to get one and what size it actually is? I attached a part of the schematic showing it and circled in red.Drew

author: andy3055
author_rank: Super Contributor
timestamp: July 05, 2024, 10:07:09 pm
content: If you really want to know what it is, go here:https://www.mouser.com/ProductDetail/Vishay-Cera-Mite/562CAA102EH103PA65?qs=t%2Fk8jExiEqsvl%2FpbczS2HA%3D%3DYou can get these any place and not necessarily at Mouser. It is a 0.01 micro Farad.Here is a good place to find information on caps:https://www.buildcircuit.com/capacitors/

author: wraper
author_rank: Unknown
timestamp: July 05, 2024, 10:07:18 pm
content: It's 10n, for the size look on PCB.

author: Crambone
author_rank: Frequent Contributor
timestamp: July 06, 2024, 12:08:40 am
content: The one I need to replace is a SMD ceramic I thought the value was .01uf . Aren’t the codes different for ceramic disk and SMD?
Capacitor Identification Help - Page 1
Forum section: electronics / beginners

author: jimbycat
author_rank: Contributor
timestamp: August 20, 2020, 10:09:32 pm
content: I removed a faulty capacitor (see image below) from a Yamaha TSR-7850 receiver's power supply board. After extensive internet searching, I cannot find a replacement part.Given its markings, do you know the capacitance value and type of capacitor it is? Voltage rating?Any help will be greatly appreciated.

author: TimFox
author_rank: Super Contributor
timestamp: August 20, 2020, 10:13:21 pm
content: How large is it, physically? The markings look like 5.1 (pF, nF?) from Ceramite (formerly Sprague, now Vishay).

author: jimbycat
author_rank: Contributor
timestamp: August 20, 2020, 10:23:50 pm
content: The diameter of the disc is 14 mm.

author: exmadscientist
author_rank: Frequent Contributor
timestamp: August 20, 2020, 10:43:33 pm
content: More likely from that marking (and origin) that the vendor is Murata. That doesn't help you with what you really want to know, but it might help orient you in the right direction....

author: wraper
author_rank: Unknown
timestamp: August 20, 2020, 10:46:48 pm
content: Not faulty since it's not even a capacitor to begin with but NTC thermistor.

author: TimFox
author_rank: Super Contributor
timestamp: August 20, 2020, 11:41:57 pm
content: Correction: The Ceramite marking is CM, not the nested letters in this photo. Ceramite also makes thermistors in this package, originally used for disc (single-layer) capacitors.

author: jimbycat
author_rank: Contributor
timestamp: August 21, 2020, 12:45:56 am
content: Thank you very much for identifying thecapacitorthermistor for me. I was able to measure its resistance with my meter, and it is working fine.Now I have to find the real problem in the power supply...
Capacitor Identification  Red - Page 1
Forum section: electronics / beginners

author: JustMeHere
author_rank: Frequent Contributor
timestamp: August 30, 2019, 08:17:22 pm
content: What type of capacitor is the red ones? I can see what's wrong with the aluminum electrolytic (black) ones. Should I replace the red ones too?

author: Tomorokoshi
author_rank: Super Contributor
timestamp: August 30, 2019, 08:34:36 pm
content: The red ones are likely Aluminum-Polymer. They shouldn't have any cases of capacitor plague. I can't make out the manufacturer. Can you list it or get a clear shot of any marks on it?

author: rcbuck
author_rank: Frequent Contributor
timestamp: August 30, 2019, 09:28:03 pm
content: I have seen the same red marking of Wurth Elekronik capacitors. It is irritating as hell since the marking is the negative terminal. The marking goes against centuries old tradition of marking the negative terminal black. The Wurth ones are just standard electrolytic capacitors. It is really confusing at first as the data sheet is a black and white document. At least it does show the marked terminal as being negative. Maybe a new fresh engineer just out of school thought red would be a nice color?This Mouser number is one I have in stock: 710-865060345007 Wurth refers to them asREDExpert parts although they are just plain vanilla parts.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: August 30, 2019, 10:14:41 pm
content: Here's a better photo
Capacitor Manufacturer Identification - Page 1
Forum section: electronics / beginners

author: meeshu
author_rank: Newbie
timestamp: February 21, 2020, 10:18:35 am
content: Trying to identify the manufacturer of a capacitor as shown in the enclosed photograph.This image taken from badcaps.net forum.Tried searching throughbadcaps.net forumand capacitor identification databasehere, but with no luck.Anyone know who is or was the manufacturer of this capacitor, please?

author: Gyro
author_rank: Super Contributor
timestamp: February 21, 2020, 11:29:47 am
content: Badcaps is all about Electrolytic caps. That's not an Electrolytic. It's hard to tell which without scale, but it's either a multilayer ceramic or polyester film. If the value measures correctly then put it back.Sorry, I can't help with the manufacturer, but it looks Japanese and fairly old.

author: meeshu
author_rank: Newbie
timestamp: February 21, 2020, 10:54:16 pm
content: Thanks for the comments.I believe the capacitor might be a polypropylene or a polyester type from a Japanese audio amplifier. The capacitor therefore might indeed be a Japanese brand, but perhaps from a now discontinued manufacturer?
Capacitor meters - Your Suggestion? - Page 1
Forum section: electronics / beginners

author: Keken
author_rank: Contributor
timestamp: August 12, 2014, 01:10:56 am
content: I'm not looking for something expensive here, budget on this would be about $20.Any recommendations on a meter to read capacitors?

author: VK5RC
author_rank: Unknown
timestamp: August 12, 2014, 01:31:06 am
content: https://www.eevblog.com/forum/beginners/cheap-lcr-meter/
Capacitor military code identification - Page 1
Forum section: electronics / beginners

author: cheeseit
author_rank: Regular Contributor
timestamp: November 28, 2016, 09:26:23 pm
content: It may be simple but I give up.. These military codes confuse me and I've tried searching, and have found various sources, but I can't get it right. I have 30-50 of each and a hint of OCD means that I must know and inventory it accordingly. I'm sure some of you know the feeling so please help me decipher these.Silver mica, perhaps?CM is molded case.8R0 and 680 is 8pF and 68pF respectively.Sang could be Sangamo?And this is where I get confused.. Which letters are tolerance, temperature and voltage? Drift?1)Front: CMR4C 8R0DPBack: DP-J 8619 (SM is vertical)Maybe 300V, 8pF, +/-0.5pF, -55 to 150 °C2)Front: CMR4C 8R0DOBack: (CD is vertical) DR-J 8521AEMaybe 300V, 8pF, +/-0.5pF, -55 to 125 °C3)Front: (SANG is vertical) CMR4E 680FOBack: DL-J 8640 (FS is vertical)Maybe 600V, 68pF, +/- 1%, -55 to 125 °CThen there are date codes like 8640 with no suffix, but also 8521AE and 8619SM (I think, SM is vertical). Suffix might be irrelevant. What does DP-J, DR-J, DL-J, SM, CD, AE and FS mean, manufacturer and/or manufacturing codes?

author: rf+tech
author_rank: Frequent Contributor
timestamp: November 29, 2016, 04:51:19 pm
content: Hi cheeseit,You have deducted most of the markings correctly and yes these are all high reliability silvered mica.In addition to Sangamo in example 3, CD in example 2 is Cornell Dubilier. Example 1 manufacturer is unknown.CMR4Cindicates -200 to +200 ppm/°C temperature coefficientCMR4Eindicates -20 to +100 ppm/°C temperature coefficientDP andDO indicates +/- 0.5 pF toleranceDPindicates –55 °C to +150 °C temperature rangeDOindicates –55 °C to +125 °C temperature rangeFO in example 3 is ±1% tolerance andOas above.-Jis a mystery - most often J indicates a 5% capacitance tolerance. Obviously, this does not apply.SM,AEandFSlikely indicate the respective manufacturers' facility/country of origin.The full CDE datasheet is available from the link below:http://www.cde.com/resources/catalogs/CMR.pdfRF+ Tech

author: cheeseit
author_rank: Regular Contributor
timestamp: December 16, 2016, 11:35:44 pm
content: I totally forgot about this thread and didn't see the topic reply notification mail, sorry about that. Thank you very much!If I understand correctly, I believe I got the voltage wrong. DP-J and DR-J signifies both 500V and failure rate of 0.1%/1000hrs and 0.01%/1000hrs respectively, correct? DL-J would also be 500V then.

author: rf+tech
author_rank: Frequent Contributor
timestamp: December 17, 2016, 08:09:52 pm
content: Hi cheesit,Yes, I think you have it correct on the voltage and reliability interpretation.RF+ Tech

author: vk6zgo
author_rank: Super Contributor
timestamp: December 18, 2016, 03:57:26 am
content: Nothing to do with the code,but I'd like to point out something interesting about that type of package.On rare occasions you may run intoresistorsin the same package.
Capacitor on output of buck led dimmer? (meanwell LDD) - Page 1
Forum section: electronics / beginners

author: Sounduser
author_rank: Contributor
timestamp: May 25, 2020, 06:13:26 pm
content: Hi, Is there any reason I cant put a capacitor on the output of a meanwell LDD- H led driver?Its essentially a buck converter, controlled by a pwm signal.The data sheet doesnt say anything.https://www.meanwell.com/Upload/PDF/LDD-H/LDD-H-SPEC.PDFThe light makes cameras have lines on the pictures.I tried a 4700uf capacitor on the output and the lines went away.Any ideas?

author: wraper
author_rank: Unknown
timestamp: May 25, 2020, 06:20:45 pm
content: If dimming is used, you shouldn't do that. If not, probably it will be OK, though 4700uF sounds troublesome during startup. And if dimming is used, you better disable dimming rather than search for troubles with capacitor.

author: Sounduser
author_rank: Contributor
timestamp: May 25, 2020, 07:42:02 pm
content: I realise 4700 is very high. I just had that to hand at the correct voltage.I didnt think it would be a good idea. or everyone would be doing it .

author: langwadt
author_rank: Super Contributor
timestamp: May 25, 2020, 09:23:54 pm
content: front page of the datasheet: EXTERNAL CAPACITANCE LOAD (max.) 2.2uF
Capacitor Outside Foil, Best testing method ? - Page 1
Forum section: electronics / beginners

author: Donknowsnothing
author_rank: Newbie
timestamp: March 21, 2022, 05:09:35 am
content: Had very mixed results when testing capacitors for outside foil, particularly capacitors with low capacitance values.What is the best way of doing this ?

author: Terry Bites
author_rank: Super Contributor
timestamp: March 21, 2022, 10:05:24 am
content: The recap man of Canada (and maybe the world) shows you just need a scope. Then he builds a dedicated tester?