hybridfree/eevblog-posts huggingface dataset:
Combination of TVS Diode + Zener - Page 1
Forum section: electronics / projects

author: Red_Micro
author_rank: Regular Contributor
timestamp: May 06, 2020, 01:25:20 am
content: Looking intothis Reference Designthey use a combination of TVS + Zener diode (D6 & D7 in the schematic) for clamping the voltage at the FET's gate. How does this exactly work? Doesn't the differences between the zener and TVS matter in this case?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 06, 2020, 01:53:20 am
content: Red_Micro and the group,That configuration is this:The MOSFET is in series with the MOSFET inside the IC U2. IT is called the Cascode configuration.The 500V Zener string limits the voltage on U2The 12V Zener limits the Vgs on the MOSFET.It is being done here to raise the maximum operating voltage of U2.Regards,Jay_Diddy_B

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 06, 2020, 11:30:57 pm
content: Why not Zener? It can be because it is much easier to find 200V & 300V TVS then 200V or 300V Zener.
Combine stop & turn vehicle signals - Page 1
Forum section: electronics / projects

author: soldar
author_rank: Super Contributor
timestamp: December 22, 2018, 09:20:50 am
content: If you have a car with separate stop and turn lights (European style) and you need to use a trailer with combined red stop / turn lights (American style) then you need a circuit that will combine the two into one. All the solutions I find online are complicated electronic circuits which need separate power supply.I had to do this years ago years ago and this is how I resolved it. It is a simple solution which only uses relays and does not need any separate supply. You need one for the left side and one for the right side so four relays in total.

author: Rerouter
author_rank: Super Contributor
timestamp: December 22, 2018, 10:32:22 am
content: You can go simpler than that, The last I heard, brake takes precedence over indicators.

author: soldar
author_rank: Super Contributor
timestamp: December 22, 2018, 11:35:27 am
content: I do not think that does what I want it to do. That would just be the brake light and no turn signal. It is not legal and, even if it were, I would not want that. I need to combine both stop and turn lights into a single light.

author: Nusa
author_rank: Super Contributor
timestamp: December 22, 2018, 01:30:29 pm
content: Modern vehicles with factory LED tail-lights and/or electronic lighting modules and lighter weight wiring may have issues directly providing the required current to the trailer directly, especially if that trailer has incandescent bulbs. Even on some older vehicles, the vehicle wiring was often marginal for anything but the most basic trailer lights.This would be my recommended generic version, giving isolation between the vehicle lights and the trailer lights. Ideally you would have a fused line from the battery (or at least from a higher-current existing wire, like a cigarette lighter) just for trailer lights.Probably should be a fourth relay on the diagram, to isolate the tail-lights as well.

author: firehopper
author_rank: Frequent Contributor
timestamp: December 22, 2018, 01:48:25 pm
content: Quote from: Rerouter on December 22, 2018, 10:32:22 amno in usa the turn signals over ride the brake signal. older cars with only one signal on each side if your turning the light blinks, doesnt stay solid
Combined driving lights and turn signals - Page 1
Forum section: electronics / projects

author: eflyguy
author_rank: Newbie
timestamp: September 15, 2019, 03:35:48 pm
content: By way of introduction, figured my first post would be a share of a project I came up with several years ago. I was inspired by the combined driving lights/turn signals on the R8, where the constant white LED strip would change to a blinking amber turn signal. I wanted these on my motorcycle, so I designed the circuit and eventually a PCB, but only made one on a wire-wrap prototype board. I installed this but sold the motorcycle a short time afterwards, and never got around to making more for my other 'bikes.Although I love tinkering on breadboard, I used the java "circuit" app on my Mac to come up with the basic circuit, then tuned the components in "the real world" before building the prototype. I have many variations, the one below is close to what I ended up building but you should get the idea.Of course, this would be a WHOLE LOT SIMPLER with an arduino these days!!! I have a joint honors EE and CS degree from '92 - I've been an EE hobbyist since around '76.Video of the prototype in operation on my bench:
Combining a stereo audio signal into either the left or right channel? - Page 1
Forum section: electronics / projects

author: Obsidianxenon
author_rank: Contributor
timestamp: July 14, 2025, 08:07:00 am
content: Hello EEVBlog forum, new here.I have a project that has a stereo audio signal, and I want to have a switch that can decide on either keeping it stereo, or making it mono into either the left or right channel. This is for the times when I sometimes have one earphone in, and sometimes both. Please note I don't want mono in both channels, just one, the other, or stereo.Cheers

author: jonovid
author_rank: Super Contributor
timestamp: July 14, 2025, 08:36:50 am
content: use a twin buffer opamp circuit so you can add the other channel to one side of stereo pairwith say a 4066 quad analog switch so you can have stereo orL to L with 50% R+L combined as mono on R ---or R to R with 50% R+L combined as mono on Lso its a three way switch.

author: Obsidianxenon
author_rank: Contributor
timestamp: July 15, 2025, 12:00:27 am
content: Thanks for the reply. Just to confirm, I can use one three-position switch for this? If so, how would I connect it up?

author: themadhippy
author_rank: Super Contributor
timestamp: July 15, 2025, 12:33:31 am
content: chuck it between your pre and power stages

author: Obsidianxenon
author_rank: Contributor
timestamp: July 15, 2025, 12:53:29 am
content: Thanks mate, you're a legend. What kind of switch would I use for that?EDIT: I figured it out: SP3T, but how do I control it with one switch?

author: Mr.B
author_rank: Unknown
timestamp: July 15, 2025, 01:01:12 am
content: Quote from: Obsidianxenon on July 15, 2025, 12:53:29 amNot quite.Use 2P3T

author: themadhippy
author_rank: Super Contributor
timestamp: July 15, 2025, 01:01:25 am
content: Quote.no its a double pole 3 way switch, a 4pole 3 way rotary switch maybe the easiest/cheapest option to find

author: Mr.B
author_rank: Unknown
timestamp: July 15, 2025, 01:05:59 am
content: 2P3T slide switch is as common as muck.Cents each on Ali.Toggle switches are a bit more difficult to find, but not totally uncommon.Agree with @themadhippy that 4P rotary may be easier to find if you don't want a slide switch.

author: Obsidianxenon
author_rank: Contributor
timestamp: July 15, 2025, 01:09:06 am
content: Understood. Thank you, I appreciate it.

author: themadhippy
author_rank: Super Contributor
timestamp: July 15, 2025, 10:15:15 am
content: QuoteBut how many are actual 3 way and not 2 way center off.

author: Mr.B
author_rank: Unknown
timestamp: July 15, 2025, 10:01:57 pm
content: On Ali they are generally listed something like 'ON/ON/ON 2P3T 8 Pin'.Example:https://vi.aliexpress.com/item/32958319752.html?gatewayAdapt=glo2vnmThe ones I have purchased in the past have not been centre off when listed as on/on/on.

author: Obsidianxenon
author_rank: Contributor
timestamp: July 16, 2025, 03:29:10 am
content: Jaycar sells a 2 pole 3 position rotary which works fine for my purposes.
Combining gapped cores Ferrite - Page 1
Forum section: electronics / projects

author: AcHmed99
author_rank: Contributor
timestamp: August 27, 2011, 01:57:24 pm
content: I

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: August 27, 2011, 11:16:48 pm
content: I could be way wrong, but I'm guessing it's not that easy and you'd end up with two cores running sub-optimally. They probably grind down the center post, so you should be able to use some silicon carbide paper and water to grind the legs, reducing the gap and getting to where you want to go. It's easy to measure the AsubL as you go.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: August 28, 2011, 07:46:24 pm
content: 'Couple other thoughts- buy cores with no gap and set the gap using very thin Mylar sheet. Here I can order cores gapped to any desired gap from the core distributors. You might be able to find a machine shop to gap cores. It's not too hard with a simple plated diamond tool on a grinder. I do pot cores on a lathe with a toolpost grinder if necessary, but the leg cores can be done on a surface grinder. I almost always use pot cores because it's easy to deal with the gap. I've also put narrow slots in toroids, but that's a pain!
Combining multiple designs onto a single stencil - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: January 11, 2016, 06:19:18 pm
content: I'm looking at moving lower complexity designs in-house to reduce cost. I typically like to panelize my own designs and recently though of combining related designs onto a single stencil.Is there a simple (low cost) program to just combine the silk screen layers into a single file to be able to do this, or is something like this typically sent out to a layout guy to take care of?

author: ajb
author_rank: Super Contributor
timestamp: January 11, 2016, 06:39:21 pm
content: What software are you using to design the PCBs? Most have some facility to combine designs either built-in or through user scripts. That feature is built-in with Altium Designer in the "embedded board array" tool; I don't know if they brought that into CircuitMaker or Circuit Studio. In Eagle you have to use a user script.As far as standalone programs, Pentalogix Viewmate can manipulate gerbers well enough, but in order to save the edited gerbers you'll need the $95 Deluxe version.

author: Pack34
author_rank: Frequent Contributor
timestamp: January 11, 2016, 07:26:40 pm
content: I'm using Eagle.I hadn't thought of that. I could just import all of the designs into a single file, then move stuff around.The only problem is that not everything is in a single PCB design tool...I'll probably look at picking up a copy of Viewmate.Thanks!EDIT:// They seem to be running a 50% sale if you login and download the free version.

author: rx8pilot
author_rank: Super Contributor
timestamp: January 11, 2016, 10:27:50 pm
content: I do my stencils this way, about 6 different designs on a single stencil. I can't remember off the top of my head what software I used, but it was free and allows me to use 6 individual paste layer gerbers and lay them out.When I get back to my office I will check the name. For prototypes and pilot runs, it has been an easy way to save money. I can get a full frame stencil and do 6 designs with fine pitch.Sent from my SAMSUNG-SM-G890A using Tapatalk
Combining the two 12V AC outputs on a transformer? - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: June 21, 2020, 07:45:17 pm
content: I have attached a picture of the transformer I'm talking about.Since it only have one Neutral/return lead instead of 2 for each of the windings, I'm guessing I will not be able to combine the two blue wires to get 12V output as that would be like shorting the transformer out am I correct?The reason being I need this for a project that requires 12V AC input instead of the 24V between the two blue leads and since it is rated at 24VA, does that mean I can draw that much power from it even if one of the windings are used or does it mean I can only draw a max of 1A from the 24V output?

author: madires
author_rank: Super Contributor
timestamp: June 21, 2020, 08:08:31 pm
content: Yep, the phases of the two blue wires are inverted, i.e. 180° apart. And each 12V winding will provide 1A.

author: Benta
author_rank: Super Contributor
timestamp: June 21, 2020, 09:00:18 pm
content: If you're able to get to the center tap (the black wire) inside the transformer and open that connection, you can parallel the two secondary windings for 12 V, 2 A.Your picture does not show enough for more information.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 21, 2020, 09:17:41 pm
content: If you're rectifying it to DC, you can use a full wave rectifier instead of a bridge rectifier.
Combining two different style antennas in to one signal. - Page 1
Forum section: electronics / projects

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: July 13, 2014, 07:20:18 pm
content: Im not a part of any HAM forums, being new to SDR im not sure of any good forums for these type of questions. I figured there are plenty of people here that are in to RF though.Im building a 3ft discone for reception down tords 75mhz, I plan to mount it on my roof along with a preamp, then run the coax in to my house. I have seen commercial discones with HF antennas mounted on the top and im curious how you do this? I would also like to build a smaller higher frequency discone and merge its signal in to the same path. I believe this is called a diversity array?In the end preamps are expensive, so I am looking to try to cover the whole RTL SDR band with a few antennas that run in to one preamp then in to a single feedline off the roof in to the house. Is this possible?Also as a side question, if you have a good preamp will you see any benefit from using an active antenna?

author: babysitter
author_rank: Frequent Contributor
timestamp: July 14, 2014, 07:44:15 am
content: Putting 2 or more antennas signals thru one cable is normally done by diplex filters, which consist of two or more band-pass filters. Basically they only prevent that a signal which is off-range for one of the antennas doesnt go there. Comparable to the crossover networks in your stereo, directing bass to the subwoofer and higher frequencies to the high-band speakers.You might find some interesting parts in the cable internet access products, I could imagine a wall plate with a TV port (47 MHz and up) and a Data upstream port (maybe up to just below 47 MHz, read specs, could be dependent on your region) might match your requirement of splitting between your vhf discone and a shortwave antenna.If you dont consider designing your own diplexer, have a look at RF relais. You get them ready made as satellite tv accessories.Using a preamp at some other place than right at the output of the antenna is quasi forbidden, e.g. behind a cable length or a relay. This will give quite a blow to the performance. If you really want to do it, run shortest possible cabling from the antenna to the relay and from the relay to the amplifier.
Command 2 different Zettler AZ850 Microrelay each by two different switch - Page 1
Forum section: electronics / projects

author: SimoS
author_rank: Newbie
timestamp: February 04, 2019, 08:07:06 pm
content: Hello. I hope this is the right section to post this question about my project.I'm working to the renovation of a a tube amp and needed to have internally two relay (one for switch between 2 different master volume, the other to insert the lead channel) with 2 commands (on the front panel / by a footswitch).Unfortunately the only available voltage is the 6,3Vac of the heaters, but I cannot use it continously.The other issue is that the Zettler relay (a bistable latching single coil) need +/- in one sense to switch in one sense, and -/+ (reverse) to switch in the other sense.The solution I found, also looking to a different post on this websites is the following (attached the layout of the whole project, the specific part I'm talking about is at the bottom of the layout):1) Converting the 6,3Vac to Vdc2) Sending to the coil the + Vdc (from the front panel or from the footswitch) to switch in one sense, and charging an electrolytic cap connected to the other (-) pole of the coil3) When the cap is charged the coil doesn't consume nothing more, and the only consume is related to the led4) When I switch off the + supply the cap inverts the polarity on the coil and the relay switch on the other sideI tested and the single command works good.My question now is how to manage two of this small circuits with the same supply without one interfere with the other.I introduced two diodes on the negative line but I'm not sure it's correct.Your opinion? ThanksPS Sorry for my orrible english
Commercial GSM library - Page 1
Forum section: electronics / projects

author: JVR
author_rank: Regular Contributor
timestamp: October 12, 2017, 11:18:52 am
content: Hi Gents/Ladies,I'm looking for a COTS GSM driver library that needs the minimum of work to manage SMS and multiple IP ports. My Google-fu seems weak in this regard as I have yet to turn up anything viable, so perhaps someone here has stumbled upon such a library and can point me in a direction.For what it's worth, I'm using mostly uBlox 3G Modules and Cortex-M7's connected to them.ETA: Price I'm not too fussed about if the product is worth it.

author: JVR
author_rank: Regular Contributor
timestamp: October 17, 2017, 09:23:46 pm
content: Tiny little bump, anyone?

author: diyaudio
author_rank: Frequent Contributor
timestamp: October 17, 2017, 10:57:12 pm
content: Quote from: JVR on October 12, 2017, 11:18:52 amJust write your own driver. unless this is Arduino related objective.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 17, 2017, 11:14:42 pm
content: Surely the modules already do most of the hard work, to the point that anything talking to them is going to be so application-specific that it would be pointless trying to do anything general-purpose enough to be a viable product
Commodiy <1uA Comparator with integrated voltage reference like Gainsil GS8021? - Page 1
Forum section: electronics / projects

author: incf
author_rank: Frequent Contributor
timestamp: July 11, 2025, 09:52:12 am
content: In another thread, someone mentioned the Gainsil GS8021. It is a low power, 1<uA supply current, comparator with a fairly accurate integrated voltage reference.In LCSC it is marked as discontinued.This makes me wonder, are there any dirt cheap, widely available, multi-suppler components similar to the GS8021?Currently, in non-low power applications using 3-pin TL431's as a all-in one voltage reference and comparator with hysteresis (adjustable at design time with resistor network) is what I typically do. In lower power, <1uA applications, that wouldn't work. Something like the GS8021, a comparator and a voltage reference, has the potential to be much more flexible.Alternatively, do accurate (5% or better) voltage references exist (that are dirt cheap, commodity, multi-supplier, etc.) that have a supply current of <1uA? Lots of low power comparators without integrated voltage references exist and are widely available.https://lcsc.com/datasheet/lcsc_datasheet_2203011830_Gainsil-GS8021-TR_C2978615.pdf

author: David Hess
author_rank: Super Contributor
timestamp: July 11, 2025, 04:11:59 pm
content: Quote from: incf on July 11, 2025, 09:52:12 amThere are various improved decedents of the old 270 microamp National LM10 combination operational amplifier and reference.What about the MAX4036 through MAX4039, or LTC1541/LTC1542?
common base amplifier - Page 1
Forum section: electronics / projects

author: Online Simulations
author_rank: Newbie
timestamp: February 25, 2013, 10:11:43 am
content: New online simulation:http://www.cirvirlab.com/simulation/npn_bjt_common_base_amplifier_online.phpand tutorial:http://www.cirvirlab.com/simulation/npn_bjt_common_base_amplifier_online.php
Common board to board connector (low profile) - Page 1
Forum section: electronics / projects

author: PeterFW
author_rank: Frequent Contributor
timestamp: May 07, 2016, 03:28:43 pm
content: Hello!I would like to connect two boards together and build myself a pcb sandwich.My search led me to the DF9 series from Hirose, it suits my needs perfectly.Before is settle on that, is there some sort of common connector for these things?Something that is not a speciality, available only at one vendor?A quasi standard connector many people use.The spacing between the top and bottom board can be between 4 to 4.5mm.I can put holes in both boards but only on one board can something protrude though the hole.It should mate with a decent amount of force and not easily come apart.Pitch... maybe 1mm, 0.5mm is fine too.Should be hand solderable.Greetings,Peter

author: kb0thn
author_rank: Contributor
timestamp: May 09, 2016, 01:43:20 pm
content: The DF9 work well. I've used thousands and thousands of them in a handful of products. We put an SMD female on the top of a main processor board and a TH male on the bottom of the signal conditioning board. You are right, the Hirose part can have availability problems. I've been bit by it one or twice in 8 years of using it. Try to make sure you have stock for about 6 weeks on hand.Another one I have seen in industrial board stacks is to have a male header on the bottom board poke through holes on the top board. On the top of the top board there is a bottom entry female header. This is nice because the mating height can be variable.-Jim

author: Ice-Tea
author_rank: Super Contributor
timestamp: May 09, 2016, 01:49:54 pm
content: How many contacts do you need? mPCIe might be an option.

author: PeterFW
author_rank: Frequent Contributor
timestamp: May 09, 2016, 09:44:29 pm
content: Quote from: kb0thn on May 09, 2016, 01:43:20 pmUhm... i thought the DF9 is only available in SMD?I can not find a THT version of it, that would be ideal if there was a THT version of it.SMD on the top board and THT on the bottom would be ideal.QuoteThat is what i wanted to do in the first place but i have a bit of a problem fitting everything in this small case, i do not really have room for screws/spacers in the part of the board were the connector sits.So i want the connector to be the "spacer", in the bottom part of the board i have screws and spacers. The Top boards gets wedged in to keep the board/connector from flexing.Hard to explain... ;^^

author: PeterFW
author_rank: Frequent Contributor
timestamp: May 09, 2016, 09:45:57 pm
content: Quote from: Ice-Tea on May 09, 2016, 01:49:54 pmThanks for the suggestion, but that one does not fit my bill
Common cathode diode array SMD IC for keyboard matrix? - Page 1
Forum section: electronics / projects

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 10, 2018, 07:13:40 pm
content: Hi,I'm looking for cheap common cathode diode array SMD IC, yes, I know common anode would work as well, but if its available as a "jelly bean" I prefer common cathode (I have found common anode IC: SMF05Chttps://www.semtech.com/uploads/documents/smf05c.pdf).I need it for button matrix reverse loop isolation (3/5V). I'm planning to assemble many boards so I'm looking a way to reduce components.

author: Gribo
author_rank: Frequent Contributor
timestamp: December 10, 2018, 08:20:04 pm
content: Is the Toshiba 1SS309 good for you? 4 diodes in common cathode.https://www.digikey.ca/product-detail/en/toshiba-semiconductor-and-storage/1SS309-TE85LF/1SS309-TE85LF-TR-ND/2071884

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 10, 2018, 08:38:04 pm
content: Quote from: Gribo on December 10, 2018, 08:20:04 pmThank You, as a components it's perfect, but sadly it's way too expensive.
Common flat-flex cable specifications for displays? - Page 1
Forum section: electronics / projects

author: analogo
author_rank: Regular Contributor
timestamp: May 28, 2023, 02:27:14 pm
content: Are there common, or "standard", specs for the flat-flex cables used in displays, in particular for the cheap no-name displays from Aliexpress?The module I'm working with at the moment requires a 22-pin 0.5mm-pitch connector. Are these common specs?

author: ajb
author_rank: Super Contributor
timestamp: May 28, 2023, 06:37:56 pm
content: Do you mean specifications for the connector geometry? That's pretty well standard, as long as you select the correct pin count, pitch, and contact side you should be fine with just about any FFC/FPC connector. Technically the 'cables' that hang off of most displays are FPC, flexible printed circuits, FFC is flat flex cable which would be something like a jumper cable, but the PCB connectors are generally the same for both.Note that there are some connectors that require locking tabs/holes in the mating FFC/FPC, or keying notches, those might not work with your display. The datasheet for the connector will usually show what sort of mating geometry the connector requires.If you mean specifications for the signal pinout on the connector, no, that's not really standard at all. Different displays can have entirely different signaling requirements, and even if the signals are the same between two displays they may not be laid out the same on the connector.
Common Ground - Amplifier - Page 1
Forum section: electronics / projects

author: vidarr
author_rank: Frequent Contributor
timestamp: May 09, 2025, 11:04:59 pm
content: I am making this cheap amp project and soldering everything together now, but not sure how to proceed with the GND wires.Some resources I read said not to mix the speaker GND wires with the PWR GND wire(s). Other sources say to create a common GND for Everything.Which is correct? This is my first amp build, so I don't know which method is right. I don't want to experiment and possibly blow some components.Thank You!

author: TimFox
author_rank: Super Contributor
timestamp: May 09, 2025, 11:16:38 pm
content: Connect the two (possibly three) wires from the power supply to the relevant terminals on the amplifier.Connect the speaker with two different wires to the relevant terminals on the amplifier.With modern amplifiers, it is quite possible that neither of the two speaker wires connects to the grounded terminal of the power supply.In such amps, the output is from an “H bridge”, in order to get more output voltage from a given power supply.In that case, grounding one of the speaker terminals will damage the amplifier.

author: vidarr
author_rank: Frequent Contributor
timestamp: May 09, 2025, 11:33:29 pm
content: I forgot to add, my house (and pretty much All houses in Brazil) don't have ground wires. So, the C13/C14 has no connection to a GND.Also, the ground of the two speakers are not connected to each other. They are also not connected to the GND of the PWR.So, as you said, this is probably an "H Bridge".There are three PSUs for this amp -- 48VDC, 12VDC, and 5VDC. The AC connections only have LINE and NEUTRAL. So, the only GNDs are the DC.I have to look again, but I think all the DC GNDs are connected together. Only the speakers are separate.Thank You!

author: Aart
author_rank: Newbie
timestamp: May 10, 2025, 08:30:47 am
content: General advice would be to keep signals and their ground between modules together, i.e. in one cable.This way the surface of the audio circuit is kept to a minimum and the design is easy to understand.Creating a silent audio system powered by (multiple-) switch mode power supplies might be hard, because these are not well insulated from the mains at audio frequencies.Tests with an old fashioned but well insulated wall-wart with a 50 Hz transformer as a power supply might help in debugging this. Solutions to these kind of problems include audio transformers to insulate signals, balanced audio interconnects to achieve this electronically or well insulated power supplies.

author: MariuszD
author_rank: Regular Contributor
timestamp: May 10, 2025, 08:57:55 am
content: Quote from: vidarr on May 09, 2025, 11:04:59 pmSome amplifiers have single ended output, some have bridge output. I don't know what kind of amplifier you have but it looks like class D. Class D often have bridge output. If this is bridge output don't make short circuit between output and ground.
Common Mode choke for 4-20mA input - Page 1
Forum section: electronics / projects

author: yashrk
author_rank: Frequent Contributor
timestamp: December 07, 2020, 10:40:57 am
content: Hey guys,We are going throughIEC 61000-4-3IEC 61000-4-6 test for one of our products.The input power source for the device is the same line which will be used for 4-20mA. Mostly it will be connected to 24V DC input (max 35V)For passing the test we are putting in a common mode choke on the line. We have low update rate in the range of tens of hertz. Now for AC (Mains) line it is recommended to use X & Y capacitor. But for our application as we don't have such a high voltage do we need the Mains AC rated capacitor or we can get away by using normal ceramic 100V caps? As you can imagine we do have space constrain.Thanx!Yash

author: bjbb
author_rank: Contributor
timestamp: December 07, 2020, 09:17:08 pm
content: Do not understand discussion of x/y caps for radiated immunity tests.'X' and 'Y' are cap safety ratings for stuff that are intended to be used for various configuration where Class I or II construction is used for protection from shock (actually x-caps are not intended to provide protection from shock), and are typically associated with design requirements for passing conducted emissions tests for connection to AC mains. DC mains have different requirements and test conditions (see -4-6).

author: yashrk
author_rank: Frequent Contributor
timestamp: December 08, 2020, 04:26:59 am
content: Sorry my bad I meant IEC 61000-4-6Ok, some more context here.So I know that common mode choke is used primarily for passing conducted emissions. We only have linear regulators so it's not a issue for us.The problem which we are facing is with conducted susceptibility were we are having drifting in our sensor reading and also random keypresses on our membrane keypad if the de-bounce delay is low.Quote from: bjbb on December 07, 2020, 09:17:08 pmThing I know is that we need to add common mode and differential mode filter to remove all the the noise. For differential mode noise we are adding two ferrite beads on 24+ anf GND with capacitor in between hence forming a LC filter.Now for common mode noise we know that we need a common mode choke. But all the examples and the literature I have about the common mode choke is with respect to AC mains supply and not much information for DC supply. The main issue we are having is with the safety capacitor.As we are not working with mains voltages do we need safety capacitors or we can work with generic appropriately voltage rated capacitors?

author: yashrk
author_rank: Frequent Contributor
timestamp: December 09, 2020, 03:54:09 am
content: Anyone??
Common mode chokes needed for wires going off PCB? - Page 1
Forum section: electronics / projects

author: makebit
author_rank: Unknown
timestamp: October 10, 2025, 09:39:40 pm
content: Hi,We have a wearable electronics product which helps diabetic people to stay cool. Diabetics' sweat glands get blocked up as they sweat out sticky material rather than just water. As such, they need external water on their body to cool them on sunny days.As such, we have a small 5V water pump which sets on the shoulder, and is wired to a PCB and battery on the waistband which also has wires going off to temp sensors all over the body. The person wears clothing with porous tubing and when the pump pumps, some water exudes over the body and cools them.Will the wires going from waistband PCB to pump need common mode chokes on the waistband PCB? Also, should we have common mode chokes for the wires going off to the temp sensors?With all this wiring, all wires are antennas, and so without common mode chokes the person will be an EMC polluter…would you agree?

author: fourfathom
author_rank: Super Contributor
timestamp: October 10, 2025, 11:37:00 pm
content: Quote from: makebit on October 10, 2025, 09:39:40 pmNo, I wouldn't necessarily agree. Relatively low-speed sensors can get by with R/C or ferrite-bead/C bypassing. This will take care of RF ingress and egress. That's for linear sensors -- if you are using some serial digital interface, then yes, a common-mode choke may be more appropriate, but you still need to consider emissions and sensitivity due to physical and electrical imbalances.If you are sending DC to the pump, it can probably get by with capacitor bypassing. For PWM or similar pump control you might want to use a common-mode choke (and capacitors), so you don't need to size the choke for DC core saturation limits.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 11, 2025, 09:20:00 am
content: I'm sure you've already seen the liquid cooler shirts used by F1 drivers. This may also interest you:www.compcooler.comEMI is a two way street. Pick up from our polluted radio environment and can be just as much of a problem.It all comes down to minimising loop areas. Ferrites, common mode chokes and bypass capacitors are, I think, the second line of attack.They all close down loop areas but good wiring practice is the best place to start.I'd use screened twisted pairs for the lead wires and comewhat less effective parallel pairs.A twisted or parallel pair is a common mode choke in its self.https://emianalyst.wordpress.com/2016/08/31/how-cable-twisting-improves-emi/Connect the cable screen(s) and drain wire (if present) at the pcb end only.You can get multipair cable with individually screened pairs for maximum effectiveness.That reduces crosstalk between your motor and the sensors.eg Alpha Wire EcoCable Mini. Im sure you can get thinner versions elsewhere.also see Belden, Raychem, Lapp, Hew, Samtec etc...https://medium.com/@emianalyst/effect-of-cable-twisting-on-radiated-emissions-66edb16bec1c
Common-mode current sensing in the NG 304 power supply - Page 1
Forum section: electronics / projects

author: profdc9
author_rank: Frequent Contributor
timestamp: May 02, 2020, 01:29:28 am
content: In another thread a really cool resource was mentioned, the manual to the NG 304 power supply:https://www.mikrocontroller.net/attachment/412953/DBL_BEHA_NG304_MANUAL_DEUTSCH.PDFSo I looked at the schematic (which I have included a copy of), and there is an interesting feature which I have drawn red boxes around. Normally the current sense resistor is on the low side of the power supply, and so as the current increases the negative output of the supply is lifted off of ground. However, in the NG 304, the sense resistor is on the high side.Now I was thinking of using this approach, but there are two potential problems I thought I identified:1. The common-mode rejection of the op-amp must be really good to ensure that the current sensing threshold doesn't depend on the output voltage level.2. The circuit is not really a difference amplifier, only a comparator. But if used to actually measure the quantitative current in the circuit (for example putting in a meter), the ability of the circuit to reject the common mode would likely be limited by how closely the divider resistor networks to the + and - terminals are matched to each other. This problem occurs in something like an instrumentation amplifier I suppose.So why is high-side sensing like is done in the NG 304 not done more often? Is it because of the difficultly of the common-mode rejection when the output voltage changes?I'm just curious but it's not something I've seen in many power supply designs.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 02, 2020, 02:18:59 am
content: Hi,This isn't really high side current sensing.The common for +/-12V supply is connected to the positive output terminal. So from a signal point of view the positive output is signal ground.I have marked the ground connections in greenThey have a 5V6 Zener and diode in series for temperature compensation.This is fairly common in power supplies. A lot of the HP power supplies were designed like this.You can make high voltage power supplies without using high voltage op-amps or level shifters.Regards,Jay_Diddy_B

author: profdc9
author_rank: Frequent Contributor
timestamp: May 02, 2020, 03:02:06 am
content: Thanks for the information. I was a bit confused about that from the schematic and so your help saved me from going down the wrong rabbit hole. I suppose then for a high voltage supply the two sets of windings on the transformer must be well insulated from each other so that the current return is only through the box and upside-down-T shaped terminals.That is still an interesting idea however but it requires a special transformer or a pair of well-insulated transformers to do it.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 02, 2020, 03:52:43 am
content: Hi,By high voltage I mean 60 or 100V maximum output (in this context).Regards,Jay_Diddy_B
Common mode EMI emissions in handheld devices (mains isolated) - Page 1
Forum section: electronics / projects

author: luisprata
author_rank: Regular Contributor
timestamp: June 27, 2018, 04:41:11 pm
content: Hi,When a product uses an external SMPS it's common to use a clamp ferrite to reduce EMI without redesign.My question is: In a handheld product is a clamp ferrite effective ? In other words, could a handheld device, not connected to mains at all, produce EMI common mode noise ?Handheld device ASCII diagram:Battery ====== switching boost ======= ProcessorDo a system like this generate common mode noise?Is a ferrite clamp effective anyway to reduce EMI ? Like this:Clamp FerriteBattery ====== switching boost =====()()()()==== ProcessorThank you.Luis A P Barbosa

author: jbb
author_rank: Super Contributor
timestamp: June 27, 2018, 07:58:59 pm
content: Remember there are conducted and radiated emissions.If the product is totally unplugged, there's no path forconductedemissions, but radiated emissions must still be considered. Common mode vs differential mode will be relevant only in the way that they drive accidental antennas which radiate emissions.If the product plugs in (e.g. to charge via a plug pack adapter), then there is a path for conducted emissions again. Note that some products are designed (in the firmware, I guess) so that they don't work while plugged in to charge. This could be for functional, safety or EMC reasons.Quote from: luisprata on June 27, 2018, 04:41:11 pmEMC is a really tricky subject because, as the frequencies go up,everything matters. What stage of development are you at and (if you're in testing) what are you having trouble with? If possible, some diagrams (or photos) will get you much better help on a forum.
Common mode filter, ground plane & bus - Page 1
Forum section: electronics / projects

author: Tantalum
author_rank: Regular Contributor
timestamp: June 17, 2022, 05:21:35 pm
content: HelloI need to power and communicate with a MCU over a cable of several meters.I will use 24VDC and a 1-Wire bus.I need to use a common mode and differential mode filter on the input of the board.But now I have those 2 questions:1. What about the ground reference and the 1-Wire bus? Is the common mode filter on the 24V/GND line a problem? Will I need to decouple the 1-Wire signal also with an isolator?2. How do I trace the 1-Wire bus on the PCB since there is a ground plane "discontinuity" because of the common mode choke? Do I need to trace the 1-Wire underneath the inductor to reduce the ground loop?Thanks

author: npeter
author_rank: Newbie
timestamp: August 28, 2022, 12:50:46 pm
content: I'm facing with basically the same issue. What is the recommended way to handle I/O signals if the ground is separated with a common mode choke between the source and the destination?I'm also thinking of using some kind of isolators (like the ADuMs from Analog Devices:https://www.analog.com/en/products/adum142e.html).

author: Terry Bites
author_rank: Super Contributor
timestamp: September 02, 2022, 03:08:07 pm
content: An isolation barier will negate CM problems. The signal "floats" on top of the CM voltage. seewww.maximintegrated.com/en/design/technical-documents/app-notes/5/5134.html

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 02, 2022, 05:58:39 pm
content: See:https://electronics.stackexchange.com/questions/632875/signal-reference-with-common-mode-filter-on-the-power-lines/632909#632909Tim
Common mode question - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: December 13, 2018, 08:52:56 pm
content: I'm designing a metering circuit using this part:https://www.mouser.com/ProductDetail/Analog-Devices/AD71056ARZ?qs=sGAEpiMZZMt%2foy9k%2f5obbU0YfL1ODTen%252b2QsC6lnqmU%3dDatasheet:https://www.mouser.com/datasheet/2/609/AD71056-877305.pdfOn page 12 of the datasheet in typical connections, they connect AGND of the AD71056 circuit to the "Phase" wire: for both the voltage and current, so from an earth ground perspective the entire circuit is bouncing around at the phase voltage. I don't see the advantage of this over referencing AGND to the neutral side will be close to 0V (earth potential)?In my case I will be using PT's and CT's for isolation.

author: capt bullshot
author_rank: Super Contributor
timestamp: December 13, 2018, 09:02:01 pm
content: This is usually done when a shunt is used as the shunt is supposed to sit in the live wire. No need to do so if you use a CT, AGND could be tied to neutral then.Anyway, referencing the AGND to neutral isn't better in terms of safety, as one has to consider the neutral "live" in most cases, so you should isolate the circuit as if it was at live potential.If you use CT and PT, I'd reference the circuit AGND to safety ground / earth.

author: Jester
author_rank: Frequent Contributor
timestamp: December 13, 2018, 09:18:45 pm
content: Quote from: capt bullshot on December 13, 2018, 09:02:01 pmThanks, that's exactly what I did.
Common mode supply noise in ungrounded modules, does it exist? - Page 1
Forum section: electronics / projects

author: huub8
author_rank: Contributor
timestamp: May 13, 2020, 09:13:46 am
content: Hi all,I'm currently designing a circuit/module that will be powered from long leads (several meters). In the future, there may potentially be some daisy-chaining going between the modules too. The system will be powered from between 5 and 9 volts DC. So effectively, the power leads could act as an antenna.Apart from differential noise, I am now wondering if I should also be worrying about any common-mode noise due to the long supply wires. The modules themselves are only connected to the + and gnd of the (unshielded) supply wires. The modules are encased in plastic, so I do not see how there would be any reference to earth. Am I correct in thinking that even though the supply wires are reasonably long, the lack of any shielded encasing means that common-mode noise would have no return path to the source and thus would not be superimposed on the dc of the supply wires?If not, what kind of frequencies would one expect to mainly have to filter out?

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: May 13, 2020, 10:02:52 am
content: You always have a return path to ground, in the form of capacitance.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 13, 2020, 04:15:04 pm
content: Offensive frequencies are on the order of the electrical length of the cabling. Typically 30MHz+, but long cables can be problematic much lower. For mains, telecom and so on, they use conducted emissions more as a convenience I assume (otherwise, you'd need to do a more sensitive, open-air test, with very long cables and antennas).Yes, any induced RF between grounds going in and out of a module, is a problem. Or more generally, the common mode, taking the average over all signals in the cable, weighted appropriately of course (since signals inside a bundle, or inside a shield, will count less).Tim
Common SMD package footprint chart? - Page 1
Forum section: electronics / projects

author: markbrannan
author_rank: Newbie
timestamp: August 29, 2014, 02:21:50 pm
content: I am looking for a little chart with most of the standard SMD component footprints on to keep beside my computer for when i'm ordering parts. Basically as a quick reference for "can I hand solder that?" and "how hard is it going to be to route around that?". A quick Google search doesn't really have what I want - the closest thing beingthis image.Does anyone know of or have an image like this that has, say SOIC, SSOP, MSOP, TSOP, TSSOP, uSOP and a variety of resistor/cap packages? If not, I think i'll make one and post it up here. What would other people want to see in such a reference sheet?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: August 29, 2014, 06:04:29 pm
content: http://www.electronics.teipir.gr/personalpages/papageorgas/download/2/PROSTHETO_YLIKO_2012/smd_footprints/default.asp.htm
common SMT breakout board design - Page 1
Forum section: electronics / projects

author: cnt
author_rank: Contributor
timestamp: June 25, 2019, 11:11:47 pm
content: Does anyone have a pre-panelized smt breakout board design with multiple common footprints? Its easy enough to make but i'm pretty lazy. Also i noticed you can buy them but they're way more expensive vs just sending a PCB out to china these days.

author: OM222O
author_rank: Frequent Contributor
timestamp: June 26, 2019, 06:56:54 am
content: Yes I agree. They're really expensive but I found a local seller on ebay who sold then for cheap. "Common foot prints" are SOIC and TSSOP. 14 pins is also usually the most I'll ever use. Just put a SOIC-14 footprint on top and a TSSOP-14 on the bottom. Then connect the pads to 0.1inch headers. This should take you less than 5 minutes. Also most PCB manufacturers offer panelling free of charge, so you don't need to do it in the design stage

author: LapTop006
author_rank: Unknown
timestamp: June 27, 2019, 11:41:52 am
content: Quote from: cnt on June 25, 2019, 11:11:47 pmOf all people, TI do, and again, of all the ways to buy it,Digikey was cheapest.Picked up a few a while back, after running into a case where it would have saved me a PCB spin, haven't used any yet.

author: ptricks
author_rank: Frequent Contributor
timestamp: June 27, 2019, 01:15:12 pm
content: I buy them off amazon, for 8-$10 for 20-30 pcs.search smt pcb
Common source amplifier and resistor values - Page 1
Forum section: electronics / projects

author: Frederico Acardi
author_rank: Contributor
timestamp: January 08, 2020, 12:37:11 am
content: Hi. I want to design a Common Source Amplifier. I will be using an lnd_150 :http://ww1.microchip.com/downloads/en/DeviceDoc/LND150-LND250-N-Channel-Depletion-Mode-DMOS-FETs-Data-Sheet-20005454A.pdfI need to get the most gain out of the mosfet.Yet, I don't understand how to choose the q-point for the lowest distortion (symetrical amplification) when you start from scratch with this circuit. What do I have to choose first ? Rd value, Id value, Gate voltage bias value ... ?The only thing I know is VDD=320Vdc. The Input signal will be 1.74Vpeak +4dbu. The load is 470K.And I have read "Allow 1/3VCC across Rd, Vds and R2".I could allow 1/3 VDD=107V to the gate with a 3M//1M (R1//R2). But why 1 third ?I am lost, can someone help me with a step by step how to do it, with real world numbers, not only formulas please.I will use this circuit :If you need more information I will add them.Sorry for this but I am still learning and never took an electronic class.Thank you.
PCB stackup for controlled impedance across manufacturers - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: November 29, 2024, 10:45:49 pm
content: Hi,whenever I work with controlled impedance, I typically ask the PCB manufacturer for their preferred stackup. However, it’s becoming increasingly common for my clients to prototype with one company, then move to another for production, and eventually shift to a manufacturer in the Far East as volumes increase.I’m trying to avoid the need to adjust the track gap every time we switch PCB suppliers.So, I was wondering... have any of you identified 4-layer and 6-layer stackups that tend to be "standard" or at least much more common across different manufacturers, particularly within Europe? Alternatively, are there any stackups that, even if not widely used, have values that fall somewhere in the middle range for many manufacturers, so that the track gap remains within the typical matched impedance tolerance of +/-10%?If not, how do you handle similar situations? Any advice or tips would be greatly appreciated!Thank you!

author: ftg
author_rank: Frequent Contributor
timestamp: December 02, 2024, 11:48:48 am
content: This would be of interest to me as well.