hybridfree/eevblog-posts huggingface dataset:
'CANopen Magic Ultimate' Running in Some kind of limitation - Page 1
Forum section: electronics / beginners

author: Hasan_Lat28
author_rank: Newbie
timestamp: August 27, 2025, 09:43:53 am
content: HelloI am new user of CANopen Magic Ultimate and working for a small company based in London. we want to test Canopen Magic Ultimate to simulate some sensors. the sensor reading (or registers) that we need to simulate are 28 but CANopen Magic is only simulating 13 with signal generators added. rest of the registers are also applied with signal generator but the values are stuck. the error i am encountering is 'Unable to start multimedia Timer (0)'. the support says that my windows is running into some kind of limitation. According to them i need to split up the simulation but that is not what we wanna do. We need all the registers in the single simulation. Has anyone ran into similar situation with such software? I have two licences on two laptops so i have tried different Laptops, Windows 11, Specs are above what they require, hardware shouldn't be an issue.Expecting an expert in Canopen Magic Ultimate or similar to respond specially, but in general you are welcome to share if you think that might help me with this. Thanks.

author: BennoG
author_rank: Frequent Contributor
timestamp: August 27, 2025, 12:24:47 pm
content: have you tried on a different pc / laptop.I don't know what you are exactly doing with the canopen, but writing your own tester with the peak sdk is also an option (an probably a lot cheaper)Benno

author: Fire Doger
author_rank: Regular Contributor
timestamp: August 27, 2025, 05:48:46 pm
content: Quote from: Hasan_Lat28 on August 27, 2025, 09:43:53 amYou are evaluating a product for purchase, if their support are not able to assist you on what you need then don't buy it...You can also checkout PCAN-Explorer with instruments add in, which is also much cheaper.https://www.peak-system.com/PE6-Instruments-Panel-Add-in-6.418.0.html
Can´t find datasheet for this component. - Page 1
Forum section: electronics / beginners

author: Tony.T
author_rank: Regular Contributor
timestamp: May 17, 2017, 08:01:18 am
content: It is from a Samsung multiroom (M5....WAM551) circuitboard.Haven´t found service manual for it and this component i cant find the datasheet of.208017TI 42AIt is 2 of them in this picture.Anybody that can help me with this? Best if i can have a service manual for it.thanks in advance...

author: janekm
author_rank: Unknown
timestamp: May 17, 2017, 08:35:01 am
content: Somewhat bizarrely, this appears to be a custom part number used by Samsung for a TI DC/DC converter: SN1208017DDAR.It's mentioned in this PCN, so it's likely to be the same as one of the other part numbers mentioned in that. The few I checked are variants on "4.5V to 18V Input, Synchronous Step-Down Converter".Pinouts don't match though, so it seems the part is available in different pinouts. You might be able to match the Samsung part to one of the pinouts. Or you can get the one with the Samsung part number from some Samsung spare parts vendors...
Can't fit output cap on preamp, can I put it on the receiving end? - Page 1
Forum section: electronics / beginners

author: dusan
author_rank: Regular Contributor
timestamp: September 30, 2023, 07:20:52 am
content: I'm making a piezo preamp and the board is too small and I have trouble placing as large output cap as I would like on the board. I'm using approx. 1-1.5m cable, is it the same if I place output cap at the receiving end?

author: Terry Bites
author_rank: Super Contributor
timestamp: September 30, 2023, 02:37:30 pm
content: Shift the emitter resistor to the other end of the line. No worries there.How big is your cap? You can get a 16V 10u in an 0805 size, about the same size as an smt npn.eg CL21A106KOQNFNE from MouserIs your amplifier input impedance so low that it needs a 4.7u coupling cap?It needs to be >> 20k to avoid loading the follower.Consider using a source follower instead.If you have room for a transistor, you've got room for an SC70 opamp eg LM321LV

author: TimFox
author_rank: Super Contributor
timestamp: September 30, 2023, 03:56:04 pm
content: That high-capacitance SMT ceramic is X5R dielectric, so if you use it you want the input impedance of the next stage to be large enough that there will be negligible AC voltage across the capacitor at low frequencies to minimize non-linearity problems (hence the need for a high capacitance value). Note that Mouser does not stock that particular part number (factory order minimum 200 k parts !).The emitter resistor and coupling capacitor can go at the receiving end of the line, as pointed out by Terry Bites.If you have room at the receiving end, consider using a film capacitor instead.Another reason to use an unexpectedly large coupling capacitor is to reduce the noise of the next stage due to its equivalent inputcurrentnoise generator (especially if the next stage is a BJT) due to the total impedance seen by that stage's input at low frequencies.

author: dusan
author_rank: Regular Contributor
timestamp: September 30, 2023, 04:08:02 pm
content: Quote from: Terry Bites on September 30, 2023, 02:37:30 pmInput impedance is 1700 ohm (soundcard)

author: dusan
author_rank: Regular Contributor
timestamp: September 30, 2023, 04:17:25 pm
content: I think I'll buy 10uF in 0805
Can’t fit USB 9 pins into PCB - Page 1
Forum section: electronics / beginners

author: markkoh
author_rank: Newbie
timestamp: February 27, 2021, 05:32:22 pm
content: This is an extension USB 3.0 board for a Dell U2713HM monitor.I’m replacing the two USB 3.0 Type A Female Right Angle 9Pin DIP Sockets.My problem: The new component pin layout doesn’t match the board.Are there two versions 9 pin layout? Did Dell use a custom component?

author: wraper
author_rank: Unknown
timestamp: February 27, 2021, 06:18:00 pm
content: There are more than 10 variants of similar connectors. Why do you want to replace them? They do not look broken.

author: markkoh
author_rank: Newbie
timestamp: March 03, 2021, 06:04:33 pm
content: Quote from: wraper on February 27, 2021, 06:18:00 pmThose photos are from Ebay. Both of my USB female pin and tabs are broken and already desoldered. Might be confusing to post my actual board.Thank you for taking time to reply this. Will probably have to hunt for scrap part.

author: wraper
author_rank: Unknown
timestamp: March 03, 2021, 06:53:49 pm
content: Just measure dimensions and try finding listing on Aliexpress which has drawing. This should not be some rare connector, seems pretty common.

author: mon2
author_rank: Frequent Contributor
timestamp: March 04, 2021, 11:27:53 am
content: Maybe like this one?https://a.aliexpress.com/_mt8YmEPI would check arrow.com to locate one quickly.

author: Raj
author_rank: Frequent Contributor
timestamp: March 04, 2021, 01:42:13 pm
content: God! I HATE USB FOR THIS VERY REASONFound it after 5 minutes of looking at random pictures of usb socket on google-https://www.globalsources.com/USB-3.0/USB-3-0-A-type-Connector-1159810079p.htmit seems to be rare. It's "Reverse Right Angle DIP" variantuse the keywords female usb 3.0 type A 'Reverse' Right Angle DIP on google eg-https://www.google.com/search?q=female+usb+3.0+type+A+%27Reverse%27+Right+Angle+DIP&tbm=isch&ved=2ahUKEwiqjMnO4pbvAhVR2XMBHebJDYoQ2-cCegQIABAA&oq=female+usb+3.0+type+A+%27Reverse%27+Right+Angle+DIP&gs_lcp=CgNpbWcQA1CRYVjPaGDpbmgAcAB4AIABkAGIAZgCkgEDMC4ymAEAoAEBqgELZ3dzLXdpei1pbWfAAQE&sclient=img&ei=L-RAYOq4ENGyz7sP5pO30Ag&bih=625&biw=1360&rlz=1C1CHBF_enIN884IN884#imgrc=1YoBV5Hz89a3-MALSO USB C sucks, as usb b micro wasn't hard enough to solder by hand.In op's pic, the original board has usb connection pads away from PCB, the common one has towards PCB...if you were to put both of them on same board, you'd have to flip the connector by 180 degrees when you change between them.

author: wraper
author_rank: Unknown
timestamp: March 04, 2021, 01:47:49 pm
content: Quote from: mon2 on March 04, 2021, 11:27:53 amIt has reversed pin order since contacts are on top side, not bottom side. He needs connector like this. With contacts on bottom side and straight shell pins.

author: kjr18
author_rank: Regular Contributor
timestamp: March 05, 2021, 02:34:26 pm
content: Looks like you need this: GSB311A31CEU. You can get in on tme.eu Dunno about other places.Or GSB311A41EU. Found it on Digikey.
Can’t ID this part. - Page 1
Forum section: electronics / beginners

author: Ron R
author_rank: Newbie
timestamp: February 13, 2023, 11:56:43 pm
content: This is an early 2000s German dual lamp dimmer out of a floor standing lamp.No response from mfr.All components test good in and out of circuit except S1 ( 5/8 dia. round silver two contact soldered on part.Probably a conductor or choke. But wouldn’t that be labeled L1 ?It reads open. I have searched through Digikey and Jameco but can’t find anything that looks like it.I will try to attach a photo.Thanks for any help.

author: Kim Christensen
author_rank: Super Contributor
timestamp: February 14, 2023, 12:24:34 am
content: Since it's labeled S1, it's probably a thermal switch. Looks like the missing fuse is in series with it and it's switching a connection between J1 and J2. Do you have a diagram of how this board connects to the lamp or know what is wired to J1 & J2?

author: ataradov
author_rank: Super Contributor
timestamp: February 14, 2023, 12:25:40 am
content: Looks more like a tilt switch. There may be a ball rolling inside shorting the center pin to the dome. "S1" would make sense in that case. Not sure why it would be in the lamp though.Try to measure continuity in different orientations.And yes, thermal switch makes more sense. But it is likely a switch of some sort.And on a closer look, it is in series with mains (?), it would not be a simple tilt switch, it would not last long.

author: james_s
author_rank: Super Contributor
timestamp: February 14, 2023, 12:39:43 am
content: Quote from: ataradov on February 14, 2023, 12:25:40 amI think you nailed it. Floor standing lamp, tilt switch will shut it off if it gets knocked over thus preventing it from causing a fire. I've never seen that feature in a lamp but it is common in space heaters, and back when halogen torchier lamps were popular they did cause quite a few fires by coming into contact with curtains and furniture.

author: Ron R
author_rank: Newbie
timestamp: February 14, 2023, 12:59:21 am
content: Ok, wow, you guys nailed it. It is a tilt switch. When the board is mounted it faces down so it was reading open.Thank you, thank you all

author: Kim Christensen
author_rank: Super Contributor
timestamp: February 14, 2023, 01:03:24 am
content: Quote from: james_s on February 14, 2023, 12:39:43 amYup... It could be aSMD switch like this oneswitching the low voltage side of a halogen lamp. Or a different one capable of higher voltages.
Cant load current sensors into LTspice - Page 1
Forum section: electronics / beginners

author: opampsmoker
author_rank: Regular Contributor
timestamp: October 08, 2020, 12:23:49 pm
content: Hi,Trying to load allegro micro current sensors from this page into LTspicehttps://www.allegromicro.com/en/design-support...it wont work, i cant get access to the symbols.Do you know if there is a mistake in their attached guide?

author: opampsmoker
author_rank: Regular Contributor
timestamp: October 08, 2020, 12:41:36 pm
content: ok solved.............i have two ltspices on laptop, and it was "Looking" at the wrong one.One LTspice i added when i had no internet connection
Can't Locate Vgd on Datasheet - Page 1
Forum section: electronics / beginners

author: bostonman
author_rank: Super Contributor
timestamp: March 31, 2020, 02:55:34 pm
content: I'm looking for Vgd (gate to drain voltage) for a JANSR2N7616UB, but can't locate it on the datasheet.Is this something that isn't typically specified?

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: March 31, 2020, 04:19:19 pm
content: I don't think it is very common. Why is it that you need to know? If the nfet is used in the "correct way" it will exceed Vgs before Vgd anyway.

author: Wimberleytech
author_rank: Super Contributor
timestamp: March 31, 2020, 04:57:56 pm
content: Quote from: bostonman on March 31, 2020, 02:55:34 pmAre you concerned with a maximum value to avoid failure? For that you would just look at the VGS value in the max table.

author: bostonman
author_rank: Super Contributor
timestamp: March 31, 2020, 11:17:45 pm
content: It's actually for an analysis and the customer is requesting we provide maximum stress voltages with that being one of the parameters.

author: Jwillis
author_rank: Super Contributor
timestamp: April 01, 2020, 04:47:03 am
content: This is a very basic understanding but it has to do with the construction of Mosfets.In planar (IC) mosfets the Vds is equal to the Vdg because the mosfet structure is symmetrical . In discrete Mosfets The value of Vdg is much larger than Vds because of construction. So the specification is never usually stated because if the Vdg is exceeded the Vds has already been exceeded much more.

author: magic
author_rank: Super Contributor
timestamp: April 01, 2020, 06:15:34 am
content: Looking at the structure of either planar or trench vertical MOSFET, there is clearly an area where only thin oxide separates the gate from the drain. The drain-body junction must be engineered is such a way that under reverse bias, drain-side potential gradient is benign enough that voltage in the uppermost area of the drain near the gate doesn't exceed oxide breakdown limit.It seems that the worst-case condition (which still doesn't result in failure for other reasons) is gate at -Vgs(max) and drain at +Vds(max), because then the gate-drain oxide is exposed to slightly more than +Vgs(max). Interestingly, this seems to imply that every MOSFET guaranteed to withstand such condition is also certain to withstand slightly more than Vgs(max) on its gate terminal when it is driven normally, i.e. gate positive with respect to source. Hmm.Note that if you apply HV across drain and gate while leaving the source floating, leakage will presumably charge the source terminal up and cause oxide breakdown.
can't open device "/dev/ttyACM0": - Page 1
Forum section: electronics / beginners

author: Kilroywashere
author_rank: Regular Contributor
timestamp: March 10, 2019, 04:12:24 am
content: Anyone good with Linux?avrdude: ser_open(): can't open device "/dev/ttyACM0": Permission deniedI think this means It does not have admin permission to open the usb port?I just started with Linux so ....How do i allow permission to the usb?

author: ataradov
author_rank: Super Contributor
timestamp: March 10, 2019, 04:40:25 am
content: First of all check that /dev/ttyACM0 actually exists. Do something like 'ls -la /dev/ttyACM0' and look at the output. After that things start to differentiate depending on a distributive.You may need to add your used to some group (often called 'dialout').I typically just create a UDEV rule to let anyone use the port. Again, depends on the distro. In Debian based it will be something like this. Create a file /etc/udev/rules.d/90-ftdi-cable.rules (name it whatever you want, of course). The contents of the file should be something like this:Code:ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", MODE="0666"Substitute correct VID and PID for your device. Unplug and re-plug the device. This will give everyone RW access.

author: particleman
author_rank: Regular Contributor
timestamp: March 10, 2019, 05:09:50 am
content: Are you trying to use Arduino by any chance?

author: hamster_nz
author_rank: Super Contributor
timestamp: March 10, 2019, 05:27:57 am
content: Permission denied - so as you say the device exists, but you can't access it.Try either adding yourself to the dialout group (and then signing back in so you get the new permissions, or 'sudo chmod 666 /dev/ttyACM0'.There is a chance that another process is using it. Try 'sudo fuser /dev/ttyACM0' to see what process id might be guilty, and 'ps -ef' to list processes.

author: bingo600
author_rank: Super Contributor
timestamp: March 10, 2019, 09:07:58 am
content: Usually you need to add your user to the group : dialoutIn order to access the serial devices./Bingo

author: MLXXXp
author_rank: Frequent Contributor
timestamp: March 10, 2019, 09:19:35 pm
content: In addition to adding yourself the thedialoutgroup, (at least with Ubuntu) sometimes you have to disableModem Manager, which grabs the port and makes it unavailable.Check if Modem Manager is enabled:systemctl list-unit-files | fgrep ModemManagerDisable:sudo systemctl disable ModemManager.service
cant read unusual capacitor voltage - Page 1
Forum section: electronics / beginners

author: combatplayer
author_rank: Contributor
timestamp: April 12, 2017, 10:03:48 pm
content: hey guys, ive tried reading this thing for a couple days and googled around a bit, but i cant seem to find anywhere telling me how to read it.it's an old capacitor out of a broken power amplifier, it holds quite a bit of juice but i'm afraid of damaging it as i have no idea what its rated voltage is.on the side it reads:MarconCE60W-F10000uf52WVNEG.BLACK03L9as also shown on the attached picture. any help is appreciated!

author: edpalmer42
author_rank: Super Contributor
timestamp: April 12, 2017, 10:21:29 pm
content: On old capacitors you often see WVDC which stands for Working Volts DC. I'd guess your 'WV' means Working Volts. The DC part is, after all, redundant. 52 is rather an odd voltage, though. Does 50 Volts make sense for your amplifier?Ed

author: combatplayer
author_rank: Contributor
timestamp: April 12, 2017, 10:30:20 pm
content: hm i guess it does. i'm relatively new to the world of electronics to this degree, but as it had two of them and a 50-0-50v rail on its transformer, i would suspect it used one of these per 50v.thank you very much!
Can't route trace outside of device in Eagle? - Page 1
Forum section: electronics / beginners

author: KillerMidget
author_rank: Newbie
timestamp: December 10, 2020, 07:27:59 am
content: Hello!I'm trying to route traces out of this devicehttps://imgur.com/a/bIpaqre, but the dotted "trace" around it won't allow me on this layer. Does anyone know how to get around this, or remove the "ghost trace"? The IC is the DMN3190, maybe I'm using a faulty library?

author: Jeroen3
author_rank: Super Contributor
timestamp: December 10, 2020, 07:31:51 am
content: The red square is tKeepout, you can run traces trough that.If it is tRestrict you used the wrong layer when drawing the footprint.Keepout gives you an error when overlapping with other keepouts.Restricts gives you an error when touching copper. It can be used to remove polygon generation from areas.

author: KillerMidget
author_rank: Newbie
timestamp: December 10, 2020, 07:37:33 am
content: Quote from: Jeroen3 on December 10, 2020, 07:31:51 amSorry I'm very new to all this. I believe I have a restrict then because Eagle won't let me route traces past it. But I got this footprint from the internet, do you know how I could go about disabling or deleting this restrict?

author: Jeroen3
author_rank: Super Contributor
timestamp: December 10, 2020, 08:03:38 am
content: Then you'd need to edit the footprint.You can check by enablind/disabling layers.
Can't solve simulation errors in FOC model (Simulink 2020a) - Page 1
Forum section: electronics / beginners

author: cadena
author_rank: Contributor
timestamp: April 15, 2020, 06:18:24 pm
content: Hi everyone,I am trying to develop an FOC algorithm (see screenshots attached) using the Motor Control Blockset in Simulink but I am getting the following errors (see screenshot attached). I don't know waht I am doing wrong since I fed my d and q currents to my Discrete PI controllers and fed the results straight into my Inverse Park Transform. I don't know how to solve this and any help would be greatly appreciated.Simulink file OneDrive Link:https://1drv.ms/u/s!AokIrMv_d8kz3BMaImhVY_guP_N-?e=Fu1a1e
insertion board 3D body to Kicad pcb editor - Page 1
Forum section: electronics / beginners

author: win22
author_rank: Newbie
timestamp: April 09, 2020, 07:42:50 pm
content: Hi,i need to install new PCB, with similar perforations and edges as old PCB.So, i had created the new PCB body from old PCB in 3D editor, and transferred it into step format.(i had find, that it's possible to create DXF and insert it, but may be existed the way for direct 3D body insertion)How can i insert this body as PCB in Kicad PCB editor?
Can't understand '165 vs '597 PISO shift registers - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: May 29, 2021, 03:28:25 pm
content: Hi.To clarify the subject, I know how to use a '165 shift register (well at least I think), but when searching for components to buy some, I was presented with the '597 chip. And I don't understand it.Well why should one need an input flip-flop? Is it to capture a specific set of data and hold the value before shifting? Looking at the waveforms did not help much. But I'm starting feeling a bit confused: what does the '165 capture then?Thanks for the help

author: ledtester
author_rank: Super Contributor
timestamp: May 29, 2021, 03:55:53 pm
content: Have a look at the logic diagram for the 597on page 3 (Fig. 4).The 597 has an extra set of storage flip-flops which can be operated independently of the shift register FFs. The clock for the input FFs is STCP and SHCP for the shift register FFs. The logic diagram shows they are not connected in any way.In this regard the timing diagram in Fig 6. is somewhat misleading because shows the shift register clock running all the time.

author: jmelson
author_rank: Super Contributor
timestamp: May 29, 2021, 04:33:53 pm
content: On the 165, data are sampled at the end of the PL signal, the FFs are transparent latches. So, except in exotic cases, you would never sample during the shifting out of data.On the 597, you could sample duing the shifting of data without disturbing the data being shifted. Then, the PL could be pulsed to transfer the held parallel data to the shift register.Not a whole lot of cases where you'd need that, but somebody must have wanted it pretty badly.Jon

author: Benta
author_rank: Super Contributor
timestamp: May 29, 2021, 05:40:09 pm
content: Actually, the input latches are very nice. They decouple the timing of sampling the inputs from the actual data read. In my eyes, very useful.

author: Moriambar
author_rank: Unknown
timestamp: May 29, 2021, 07:04:11 pm
content: Thanks
cap between ground and active low reset - Page 1
Forum section: electronics / beginners

author: scarrier
author_rank: Contributor
timestamp: March 06, 2013, 12:49:10 am
content: I saw in a reference design : (http://www.maximintegrated.com/app-notes/index.mvp/id/4663) that they put a 100nF cap between ground and an active low reset why is that wouldn't a pull-up be more appropriate?

author: David_AVD
author_rank: Super Contributor
timestamp: March 06, 2013, 02:42:48 am
content: The cap is there to keep the pin low at power-up for a short time. I'd say there's a pullup inside the chip that charges the 100n cap. That combination gives it the momentary low at power-up.

author: Psi
author_rank: Super Contributor
timestamp: March 06, 2013, 05:35:07 am
content: There are small IC's for doing that properly. (Holding CPU/MCU reset low until the power is stable)eg, KIA70XX

author: ve7xen
author_rank: Super Contributor
timestamp: March 06, 2013, 08:12:10 am
content: That was my first thought too, and there is a weak pull-up on the pin, but on reading the datasheet the chip is supposed to include a power-on reset internally.I guess it's just there to put some energy storage on the pin so it can't be triggered as easily by EMI etc.
cap carnage - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: July 19, 2025, 10:27:16 pm
content: This is a pic of a smd electrolytic that went nuclear on the duplex modual of my wavetek 4015 enjoy!.

author: Haenk
author_rank: Super Contributor
timestamp: July 20, 2025, 10:34:21 am
content: To me it looks like the cap is just the victim.

author: wraper
author_rank: Unknown
timestamp: July 20, 2025, 10:46:43 am
content: ^Yep, capacitor has nothing to do with it. If it would be at fault, it either would vent or its can would fly away. It's obviously a part located on the left of it.

author: Zero999
author_rank: Super Contributor
timestamp: July 21, 2025, 07:13:50 am
content: The capacitor is probably fine. It just got covered in soot and tar, when its neighbour burned.

author: ME
author_rank: Frequent Contributor
timestamp: September 21, 2025, 11:24:12 am
content: This cap was missing when the unit came back to me , It was replaced by a resistor bodged in there,is that normal? .The 4015 worked fine upon return but has stopped working now with a bunch of self test fails!! could this bodge cause the fail of this 4015?.

author: Psi
author_rank: Super Contributor
timestamp: September 21, 2025, 12:30:29 pm
content: Does this circuit have high energy available in that area, like from a battery, mains or just highish voltage?Looks more like it arced rather than a normal failure you might get on a PCB where input voltage is from a DCDC or linear reg which would go into protection mode and shutdown/limit current.Is that cooked part is a SOT32 fet or reg? or maybe just a cooked diode?
cap electrolyte leakage - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: December 05, 2021, 12:59:52 pm
content: Hi all i just wondered what the main mechanism is that makes caps leak there guts,i assume mainly heat leading to pressure?,ie if i have a cap thats leaked in an smps what is better to replace it with to help stop ir happening again?,ie higher voltage rated cap,im not talking about low esr variants,i ssume heat is the main cause,ie bigger fans and better airflow?,do electrolytics exist with heatsinks?.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: December 05, 2021, 02:43:36 pm
content: Heat is not good for electrolytics.Most are only rated for 85 celcius, while the better ones are rated to 105 celcius, or sometimes even higher.ESR is an important factor because high ESR leads to internal heating.Yet another factor is external heat. Try to keep these things away from heatsinks that get hot.
cap question - Page 1
Forum section: electronics / beginners

author: krayvonk
author_rank: Regular Contributor
timestamp: June 26, 2019, 10:46:55 am
content: If I have a positive and negative pole on both sides of a capacitor, will this discharge the capacitor? (saying it was precharged before put into the circuit.)

author: Rerouter
author_rank: Super Contributor
timestamp: June 26, 2019, 10:50:43 am
content: I would say yes for the fact you are shorting the terminals of the capacitor together, you may want to rethink what you have drawnA capacitor with very little load can remain charged and then added to a circuit, just not in this case,It also depends on the size and type of capacitor for how fast it would self discharge, as most capacitors have self leakage, its a small amount for most,

author: krayvonk
author_rank: Regular Contributor
timestamp: June 26, 2019, 11:01:40 am
content: Ah yes of course. they are linking anyway... thankyou.
cap sense drift - Page 1
Forum section: electronics / beginners

author: PerranOak
author_rank: Frequent Contributor
timestamp: December 18, 2020, 03:13:36 pm
content: I've setup a simple cap sense (touch) switch with a microcontroller. It's the type where, on setup, is measures the time for an RC circuit to charge (with the sensor in the circuit but not being touched) then compares this time with the real-time charging rate moment-to-moment. As the capacitance changes with touching, the charge rate changes and the PIC detects this and toggles a LED.The "sensor" is a piece of aluminium(bloody spell check wants to replace this with aluminum!)foil about 50cm2.It works well but is erratic at times. If I didn't know better I'd say it varied with atmospheric conditions.Is this possible for small fluctuations in humidity (and temp?) to trigger it or am I way off-beam?

author: coppice
author_rank: Super Contributor
timestamp: December 18, 2020, 03:22:08 pm
content: Quote from: PerranOak on December 18, 2020, 03:13:36 pmThe capacitance of cap sense sensors usually changes quite a lot with temperature and humidity. Depending on the dielectric, you may also see storage effects that mean the capacitance doesn't switch by the full amount instantly. Any stable sensing technique doesn't jut perform an initial measurement of the capacitance. It continuously tracks the base capacitance, and looks for sudden changes that represent "use". It gets messy when you try to distinguish a slowly approaching finger from a rapid drift in base capacitance due to a rapid temperature change. Things get really complex when you are doing things like sensing on kitchen appliances, where water splashes may occur. How well this is handled is one of the key things separating a good cap sensing solution from a poor one. I've never found a cap sense solution that is impossible to fool, but some are really hard to fool.

author: PerranOak
author_rank: Frequent Contributor
timestamp: December 20, 2020, 10:42:38 am
content: Cheers, I hadn't thought it would be material.I like the idea of continual monitoring of the base level - I'll give it a shot.
cap switches sensitivity improvement methods - Page 1
Forum section: electronics / beginners

author: d_n
author_rank: Newbie
timestamp: May 14, 2014, 07:21:30 am
content: What all factors determine the sensitivity of capacitance switches? just increasing the capacitor value would help or not?? quickening the response time can lead to false detection so except this what could be the way to improve sensitivity.

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 14, 2014, 10:19:16 pm
content: Hi d_n,Can you tell us what device you are using, a micro with capacitive switch function pins or a dedicated capacitive switch IC?HalfSpace

author: d_n
author_rank: Newbie
timestamp: May 15, 2014, 09:13:24 am
content: I am using a micro for the spring type cap switches.

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 15, 2014, 10:57:45 pm
content: Hi d_n,Are you using the method in the link below?http://www.siongboon.com/projects/2007-11-29_touch_sensor/an-kd03_101-springs.pdfHalfSpace

author: d_n
author_rank: Newbie
timestamp: May 16, 2014, 03:59:11 am
content: Yes! it is the same.

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 17, 2014, 12:16:33 am
content: Hi d_n,The sensitivity of a capacitive touch switch can be increased by using a larger value sample capacitor, but could also increase the chance of false triggering. I have listed below some causes of poor sensitivity and some things to try.Poor contact between spring and touch pad PCB connection. Should be soldered or use conductive glue.Parasitic capacitance between spring and surrounding grounded objects. For example metal case or PCB ground plane. Increase clearance and or try increasing sampling capacitor value (may cause false triggering).Thickness and dielectric of touch panel material. Reduce thickness of material will improve sensitivity but not too thin as it should still be able to pass an ESD test.Touch pad too small. Flat end of spring may be too small. Printing a larger conductive pad on the back of the touch panel material which is in contact with the spring may improve sensitivity.If you are using a series resistor on the touch pad try reducing its value but this could cause ESD testing issues and false triggering.HalfSpace

author: d_n
author_rank: Newbie
timestamp: May 17, 2014, 03:49:03 am
content: have tried all of them. now i think only the software can be helpful in increasing the sensitivity without leading to false detections. .Thanks.
cap value in psu schematic - Page 1
Forum section: electronics / beginners

author: p.larner
author_rank: Frequent Contributor
timestamp: March 22, 2024, 03:21:34 am
content: In this schematic for a psu,C9 is down as a 100pf,i assume its a compensation cap for damping the foldback + minimising oscillations,can a say 330pf be used etc as i cant locate a 100pf.

author: MrAl
author_rank: Super Contributor
timestamp: March 22, 2024, 03:38:04 am
content: Quote from: p.larner on March 22, 2024, 03:21:34 amHi,That's the compensation capacitor so it should not be changed, although there is a chance that a different value would work.That cap keeps the output stable so it does not oscillate. If you change the value there is a chance that the output will start to oscillate up and down and that's not a good thing at all for a voltage regulator.However, if you have THREE of those, you can connect the three in series and that makes a cap roughly 100pf (actually 110pf).Just to note, the maximum AC input would be 25 volts AC RMS. That's because the chip takes 40 volts max.

author: p.larner
author_rank: Frequent Contributor
timestamp: March 22, 2024, 05:34:31 am
content: Thanks for the reply but ive found a good 50v 100pf cap.

author: xavier60
author_rank: Super Contributor
timestamp: March 22, 2024, 07:36:33 am
content: Increasing C9 should be fine. Stability should always be tested anyway.

author: Zero999
author_rank: Super Contributor
timestamp: March 22, 2024, 10:50:05 am
content: Why make another darn 723 thread? This is getting silly now!As mentioned above, it's a compensation capacitor. A higher value will be fine, but it will slow the transient response down somewhat.
cap value? (answered thanx) - Page 1
Forum section: electronics / beginners

author: asterone
author_rank: Contributor
timestamp: June 07, 2021, 05:20:10 am
content: Hi, can someone confirm or correct that this is a 0.01uF 630V 10% cap?and this would be a suitable replacement?https://www.ebay.com.au/itm/164095539554Cheers,

author: bob91343
author_rank: Super Contributor
timestamp: June 07, 2021, 06:20:29 am
content: You are correct.
capacitance and voltage rating of a surface-mount ceramic capacitor - Page 1
Forum section: electronics / beginners

author: RedX159
author_rank: Newbie
timestamp: July 10, 2025, 09:57:21 am
content: HiHow can I determine the capacitance and voltage rating of a surface-mount ceramic capacitor?

author: mikerj
author_rank: Super Contributor
timestamp: July 10, 2025, 10:19:10 am
content: Use an LCR meter to get an accurate capacitance value, or a multimeter with suitable capacitance ranges will get you close enough.Getting the original voltage rating is more much difficult, often an MLCC will continue working to some extent well above it's rated voltage, but depending on the type of dielectric the capacitance can considerably reduce as voltage increases. You may be able to get some idea from the part size after getting the capacitance, the higher capacitance values in a given size tend to have the lowest voltage ratings, but this won't be useful if it's a low value capacitor.

author: RedX159
author_rank: Newbie
timestamp: July 10, 2025, 10:27:49 am
content: Thank you very much for the detailed explanation and help. I truly appreciate your time and support!

author: eugene
author_rank: Frequent Contributor
timestamp: July 10, 2025, 03:16:09 pm
content: Quote from: RedX159 on July 10, 2025, 09:57:21 amIf it's one that you found loose, then don't bother. Just throw it in the trash. They are too inexpensive to spend your time thinking about.

author: TimFox
author_rank: Super Contributor
timestamp: July 10, 2025, 03:42:47 pm
content: The voltage rating on a SMT MLCC part is just a manufacturer’s guarantee that the unit will not be damaged at that voltage. They base that on sample tests during development and there is no practical way for you to evaluate it yourself.For critical applications, the reduction in capacitance with bias voltage can be measured, but as Eugene pointed out, it’s not worth the trouble for an unmarked part. It can be hard to find the relevant information on some manufacturers’ data sheets.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 10, 2025, 03:48:52 pm
content: With X7R and similar capacitors the capacitance value is not very stable. It goes down with DC bias, even well below the rated voltage. There is also some aging that tends to reduce the capacitance and this effect gets reset on heating (e.g. soldering).

author: TimFox
author_rank: Super Contributor
timestamp: July 10, 2025, 03:53:56 pm
content: Also, the case size (1206, 0403, etc.) is not a good indicator of voltage rating, although very high voltage or capacitance values often require large case size for obvious reasons.Note that “MLCC” is a construction method, and can use Class I (C0G) or Class II (X7R, etc.) dielectrics.
Capacitance meter Vs. ESR meter... FIGHT! - Page 1
Forum section: electronics / beginners

author: Shredhead
author_rank: Regular Contributor
timestamp: June 09, 2014, 09:24:02 pm
content: Is the capacitor value reader on a Fluke 87-V for example, using an ESR meter type circuit to determine the value of the cap?If it uses a different method to read cap values then which type of meter gives the more trustworthy results?

author: Stonent
author_rank: Super Contributor
timestamp: June 09, 2014, 09:44:23 pm
content: I've heard an ESR meter (as described by W2AEW) referred to as an AC Ohm Meter.It sends an AC oscillating current through a capacitor and measures how much it resists. It isn't the same as a capacitance testing, as the capacitance can be in spec but the resistance is too high so it can't empty out as easily.

author: Dave
author_rank: Super Contributor
timestamp: June 09, 2014, 10:00:16 pm
content: The key here is phase angle of voltage vs current. If you have a purely capacitive load (ideal capacitor), and you apply a sine wave to it, the phase of the voltage is going to be exactly 90° behind current.If you had a purely resistive load (ideal resistor), voltage and current would be perfectly in phase.ESR (equivalent series resistance) can be shown as a resistor wired in series with the capacitor. If you apply a sine wave to this circuit, the phase of voltage is going to be somewhere between 0 and -90°. By measuring this phase, the amplitudes of current and voltage and knowing the applied frequency, we can calculate both capacitance and ESR.

author: Shock
author_rank: Super Contributor
timestamp: June 10, 2014, 11:47:29 am
content: ESR or LCR meters are the best, unless you get an old design they also measure capacitance. Get one that uses common test frequency that can be matched to capacitor data sheets (e.g. 100kHz). If your spending around $85 check out the DER EE DE-5000 on ebay. Make sure you get one with the cables and your happy with the specs.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: June 10, 2014, 12:18:37 pm
content: Both can be different and correct at the same time.Only an ideal capacitor has one value.If you are going to use the cap as ac filter then sure use the ac measure method.If you are going to use it as some timer then the load time measure method may be better, but usually another component will control the load time so you don't really need to know it accurately.
Capacitance Meters - Page 1
Forum section: electronics / beginners

author: Chunkymonkey025
author_rank: Newbie
timestamp: October 19, 2014, 04:56:37 pm
content: Hi everyone, I'm looking at buying myself a capacitance meter but don't know what sort of brands I should be looking for to get a decent quality one without having to spend too much money or would I be better off getting a multimeter that also measures capacitance?Would really appreciate some help.Thank you

author: kripton2035
author_rank: Super Contributor
timestamp: October 19, 2014, 05:04:14 pm
content: this one has an unbeatable price/performance ratiosearch for der ee de-5000 on this forumavailable for some $80 from japanese ebay sellers - dont forget the probes.http://kripton2035.free.fr/LCR%20meters/lcr-deree5000-cl.html

author: German_EE
author_rank: Super Contributor
timestamp: October 19, 2014, 05:18:04 pm
content: The LC meter from AADE is very good and surprisingly accurate. Unfortunately the site is currently closed due to serious illness but you might find a local dealer with stock.
Capacitance Multiplier - Why are frequency and ripple not linked? - Page 1
Forum section: electronics / beginners

author: katastic
author_rank: Contributor
timestamp: June 03, 2021, 03:15:24 am
content: Hello all, hope you're doing well.According to the eevblog video on Capacitance Multipliersat around the 20:30 mark, Dave talks about how F,-3db doesn't change with beta when you add an emitter follower to the RC.But if F,-3db marks the frequency of 3 db drop on a filter... then how is the voltage ripple improving further? Aren't those two directly related? If I used a second order filter, the F,-3db would change, right? Because the signal at the original F,3db point would be now reduced, so the new F,-3db point would be at a reduced in frequency.So I'm having trouble grasping: How is F,-3db is separate from the actual ripple drop? Because if it's not, then we're not multiplying our RC constant just reducing the current through R at which point... what's the point except allowing you to use a very high value for R? That is, the circuit doesn't multiply at all but simply allows you to use a higher value for R? Is that what's going on?I don't know. There's clearly something key I'm just "not getting" about this.Thanks for any insight,--Chris Katko

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 03, 2021, 03:50:47 am
content: Draw the equivalent circuit. The transistor is equivalent to a resistance in parallel with the supply resistor. It will have some effect depending on load, but typically the supply resistor is dominant (much smaller) so the effect is small.The equivalent resistance is approximately hFE * RL.Tim
Capacitance of this phono circuit - Page 1
Forum section: electronics / beginners

author: reddish75
author_rank: Regular Contributor
timestamp: October 04, 2025, 09:11:10 pm
content: I'm trying to understand phono cartridge loading in my system and would like to know if the capacitance of this phonostage can be worked out from the schematic ( attached) and how I would do that?

author: gbaddeley
author_rank: Regular Contributor
timestamp: October 05, 2025, 07:39:18 am
content: Estimate is c403+c405=150pF + pcb & wiring stray capacitance, say 20pF. Add capacitance of interconnects from the moving magnet cartridge and it will be what will work fairly well with most mm cartridges, 200-300pF ymmv. Note the 47 k resistive loading is standard for mm cartridges.

author: Alex Nikitin
author_rank: Super Contributor
timestamp: October 05, 2025, 07:22:38 pm
content: Quote from: gbaddeley on October 05, 2025, 07:39:18 am1) C405 is connected between the amp non-inverting and inverting inputs, so it won't be 50p reflected to the input, more likely less than 10pF (depending on the NFB level at HF). So altogether the input capacitance is probably around 120-130pF + cables etc.2) The input resistance in audio frequency range won't be 47K in this circuit, only about 39K (47K in parallel to 220K), to get close to the standard 47K input resistance, R401 and R402 should be replaced by 62K .CheersAlex

author: gbaddeley
author_rank: Regular Contributor
timestamp: October 06, 2025, 11:05:17 am
content: Hi Alex, thanks for your points of clarification on my response.
Capacitive ballast? - Page 1
Forum section: electronics / beginners

author: ion
author_rank: Regular Contributor
timestamp: October 20, 2020, 10:59:09 am
content: I bought a small mercury discharge tube recently, only to find it impossible to get a suitable ballast locally. I figured out that an approximately 8H inductor would be suitable for the 5W tube, but not something I can get hold of.However, a suitably rated 1.5uF capacitor would also provide the required impedance and is easily (and cheaply) available.Is there any reason ballasts are usually inductive? Am I missing something that would prevent the capacitor from working?I suppose even a resistor should work, but the losses would be high.

author: David Hess
author_rank: Super Contributor
timestamp: October 21, 2020, 08:37:24 am
content: An inductive ballast also provides the inductive kickback voltage when the starter releases to ignite the bulb. Capacitive ballasts have to provide this in some other way.

author: ion
author_rank: Regular Contributor
timestamp: October 21, 2020, 11:55:43 am
content: Thanks. I was hoping the mains voltage would be sufficient to ignite the tube seeing as it runs at around 35V, but I'm not so sure now. I can't find any data on the required strike voltage for these kind of tubes.

author: ion
author_rank: Regular Contributor
timestamp: October 22, 2020, 08:55:20 pm
content: I decided to try it out anyway, the setup took less time than I spent trying to find the information online.And it turns out that 240V mains is not enough to ignite a 5W tube.It did seem close to igniting though, it might take less than 1kV if I can find a way to supply it without damaging the capacitor.

author: drvtech
author_rank: Regular Contributor
timestamp: October 22, 2020, 11:20:58 pm
content: Edit to add: Don't do this, it's dangerous...Reminds me of an experiment I did as a teenager - I connected up a fluorescent tube in the same way as the cheapo strobe lights you could get for a disco. Rectified mains in series with a fat resistor to charge a capacitor which was connected directly across the tube. Then a high voltage pulse from a valve audio output transformer applied between one end and an ignitor wire which was wrapped around the same end. The cap charges up and then the pulse creates enough ionised gas to start an arc. The cap discharges through the tube with a nice bright flash and the resistor ensures that the cap doesn't charge again too quickly so that the arc can't be sustained. Risky though. If you work the tube too hard it will explode! But this was 50 years ago and I was young and fearless 🙄

author: ion
author_rank: Regular Contributor
timestamp: October 23, 2020, 11:25:32 am
content: That does sound dangerous. Luckily I won't have to resort to anything that risky - I remembered I had a few old transformers and found one with a high enough inductance on one of the windings to use as an inductive ballast.Of course, now I need to reduce the inductance because the current is too low, but it's probably better to start a new topic for that.