hybridfree/eevblog-posts huggingface dataset:
Computer controlled solid state relay  - Page 1
Forum section: electronics / projects

author: HKJ
author_rank: Super Contributor
timestamp: April 22, 2019, 04:54:35 pm
content: Sometimes I do other stuff than reviews, this is a piece of test equipment.Functions:Can turn on/off any of the 3 outputs from a command or from buttons on the box.Can generate PWM with a frequency from 1Hz to 100kHz on up to 3 channelsCan generate push pull PWM with dead time on one channel using output 1 and 2.PWM frequency can be specified either as frequency or period time.PWM duty cycle can be specified either as percent or as high time.PWM has a resolution up to 0.1%Frequency can be specified with on decimalPWM duty cycle can be specified with on decimalTime is specified default in milliseconds with two decimals, some other time units can be selected by a letter after the value.Timed commands works up to 10 hoursTime specifications below 4 seconds uses hardware timers with available resolution down to 10usTime specifications above 4 seconds uses software timing with 10ms resolution.Output 1 & 2 are synchronized, output 3 can be up to 1us late.Can sequence the outputs, either with pulse length or when they turn on.Commands can be stored in the device and activated with a button for off-line usage.Outputs can handle 10A continuous and much more in peak.Can deliver pulses below 1us in PWM mode.Full project here, including schematic, software and gerber files:Computer controlled solid state relay
Computer Power supply conversion for Bench Supply - Page 1
Forum section: electronics / projects

author: kn4jhb
author_rank: Newbie
timestamp: November 28, 2019, 10:47:36 pm
content: I have two hot swapable computer server power supplies that I want to convert for bench power. Model numbers (Emacs)M1G-6500P and (Estasis) EFRP-553V3. i know that computer power supplies needed an artificial load on a specific set of pins to power up the unit and deliver all the produced voltages. Does anyone have a schematic or pinout diagram for either of these supplies? Any assistance anyone could provide would be greatly appreciated.

author: MosherIV
author_rank: Super Contributor
timestamp: November 28, 2019, 10:56:46 pm
content: HiWelcome to the forum.If by 'bench power' you mean a bench power supply with variable voltage and current limit (some refer to this as constant current) - bad idea!Your first problem is finding the pin out.2nd problem - some need a minimum load before they will regulate properly.3rd problem - they do not have current limit, they will just dump maximum current output.4th problem - they are quite noisey so not suitable for analogue work eg op-amp circuitsYou see many many people doing this but honestly it is not a good idea. Just go out and buy a bench psu. They can be picked up very cheap on ebay.There are many home brew projects for linear bench psu on the internet.
Computer Power supply fan - Page 1
Forum section: electronics / projects

author: dan3460
author_rank: Frequent Contributor
timestamp: May 05, 2017, 05:54:18 pm
content: I'm working on a prototype and i'm using a computer case and power supply to build it. I can start the power supply but the fan is full speed, before I start poking around I wanted to ask kif anyone knows how to control the fan. The power supply is a PS-4241-9HA here is a chart with the pinouthttps://arstechnica.com/civis/viewtopic.php?t=1204405. This power supply is probably an overkill but is in the case that I want to use and it is free.I'm pretty sure that pin 1 on the P2 connector must be handled by the cpu to control the fan, does any one knows how is this controlled. I have not checked yet but I can bet that that the pin labeled fan speed is a tach that produces a square wave at the frequency that the fan is spinning, I have a few other cooling fans that all do the same.

author: dan3460
author_rank: Frequent Contributor
timestamp: May 06, 2017, 02:34:51 am
content: I found on the internet a (by google fancmd) a description of a chip used by HP to control the fan speed. This is the documenthttp://www.championmicro.com.tw/datasheet/Analog%20Device/HPFANG+-.pdfon that document saidQuote. I will play more with this tomorrow but it seems that by usging a PWM signal I can control the speed that the fan runs.
Computer PSU conversion project - Page 1
Forum section: electronics / projects

author: chriskraz
author_rank: Newbie
timestamp: April 26, 2015, 12:23:13 am
content: Hey guys,I have an older computer power supply that I'm planning on turning into a static DC power supply for at home projects.Now I have originally planned on making a nice wooden box to contain the unit, but after some thought and considerations I began thinking about ground protection for the unit and the fact that a wooden box would take that out.Now if I wanted to continue with the wooden container for the PSU components, what safety considerations should I include for the grounding the unit? I have some thoughts about what I could do without having the inside of the container lined with metal, but would it better necessary or at least safer if I lined the inside with a (earth) ground plane?

author: kjs
author_rank: Regular Contributor
timestamp: April 26, 2015, 04:38:06 am
content: If you search here there are tons of conversions shown.These power supplies have a tendency to go South when used as lab supplies so I wouldn't even think about moving the boards into their own enclosure. Use it as it is and when it fails take the next one.The next thing is that they aren't good supplies in terms of ripple and stability. I "transformed" a few as I needed their high current capability but for normal lab use I would go with a linear regulator supply for lower noise. That also allows you to have a variable voltage and even more important adjustable current limiting.That's how mine look:https://www.eevblog.com/forum/projects/a-pc-psu-%28atx%29-based-lab-power-supply-the-umpteenth-version/msg621374/#msg621374

author: DanielS
author_rank: Frequent Contributor
timestamp: April 26, 2015, 01:52:13 pm
content: You should simply keep the PSU's enclosure as-is and mount it to the rear of your wooden chassis using longer screws. You want to keep the steel enclosure to protect against shorts to high voltage components, possible explosions in case of catastrophic capacitor failures and possibly fire.

author: Marc_Und
author_rank: Newbie
timestamp: April 26, 2015, 08:04:27 pm
content: The other advantages to keeping the PSU within its metal enclosure is:- Ease of installation - it is fiddly/time-consuming mounting the transformer/pcbs/etc individually, but the metal enclosure has it done already, and it will only take 2 or 3 screws to mount that.- the enclosure could be being used as part of the heat-sink for a number of the components within the PSU, which the wooden box obviously can't provide.
concept from scratch for a camera slider - Page 1
Forum section: electronics / projects

author: Johannsen
author_rank: Regular Contributor
timestamp: February 12, 2020, 08:10:12 am
content: Hi,I just finished building the hardware for a camera slider. I need it to record timelapse videos. The slider should move e.g. 1cm wait 5min take a photo, repeat, etc.Attached a first plan for the control.I was thinking of using a samd21 of an arduino zero and also program it with the arduino ide.In the final stage I would like to control it with a remote, maybe connected with rfm95 or nrf24 modules.I'm considering using a DS3231 or the internal rtc of the samd, for driving the dc gear motor a l298nWhat do you think of the concept (flow diagram)? Is such a diagram usually more detailed or what can I improve? Usually I just started to program but thought it would be a good idea to draw a plan first.
Concept of scalable n-bit comparator (cascaded) - Page 1
Forum section: electronics / projects

author: Kairat
author_rank: Newbie
timestamp: September 20, 2024, 10:05:34 am
content: Good day!This is continuation of my hobby concept of scalable n-bit comparator.This time I tried to connect comparators in cascade.I defined CMT asCMT structure.CMT truth table.Example of 4-bit cascaded comparator with comments.Thank you for in advance for your comments! I appreciate your expertise and valuable notes!
Concept of scalable n-bit comparator. - Page 1
Forum section: electronics / projects

author: Kairat
author_rank: Newbie
timestamp: September 18, 2024, 07:30:56 am
content: Greetings!This is my first topic in this forum.I want to share with you my concept of scalable n-bit comparator.Here CMN is my version bit comparator with function of 'suppression'. If input EN is 0, then all outputs set to 0.CMN structure.Example of 4-bit comparator.Note. Logic uses ‘suppression’ of next CMN blocks in chain when it determined which number A or B is greater.This is my hobby to design binary logic. I didn’t test mentioned above logic on simulator yet. I just want to believe that it should work.I would be grateful for your comments and notes!

author: brucehoult
author_rank: Super Contributor
timestamp: September 18, 2024, 07:50:17 am
content: Should work.But it will have O(N) propagation delay.A carry-lookahead adder (subtractor) has O(log(N)) propagation delay, and you can check signed & unsigned LT/GE ordering by looking at the carry out and top bit I think.I figure a simple comparison that doesn't need the result of the subtraction should be no slower -- and use fewer gates.

author: xvr
author_rank: Frequent Contributor
timestamp: September 23, 2024, 09:00:56 pm
content: Reinventing the wheel may be useful (as brain exercise for example).But if you need a result it will be better to use well known chips, like 74HC85 (4 bit, cascadeable)

author: Kairat
author_rank: Newbie
timestamp: September 24, 2024, 02:26:42 am
content: Good morning!Thanks for your advice! It's just my hobby (create logic and test it). Mostly I use Function Block Diagram for programming, so it's interesting for me to realize some common functions (like comparators, voting logics, etc.) in that environment by myself (for training purpose). To be honest, programming in FBD is more easy (I can just set desired execution order to blocks) rather try to create some logic in real hardware (I see that designer must take care about many physical factors, timing, etc.).But, long time ago (already 10 years), I used to program PIC controllers, that was very interesting to create some devices on PCB.Appreciate any comments and notes!Best regards, Kairat.

author: xvr
author_rank: Frequent Contributor
timestamp: September 24, 2024, 09:24:18 am
content: In a modern world PCBs with a sea of simple IC almost gone. Now digital hardware design is a something build from MCU, sensors, transievers etc. Logic used only as a glue leyer between them. If you want to design real hardware chemes, in a modern word it is a FPFA area.
Conceptual Noise Question - Page 1
Forum section: electronics / projects

author: Evan.Cornell
author_rank: Regular Contributor
timestamp: March 15, 2022, 12:51:09 pm
content: This may be basic analog that I learned in school, but can't quite remember the correct answer.Say one requires a 1kOhm resistor in op-amp feedback path, is it lower noise to just use a 1kOhm resistor, or instead to use some parallel combination of resistors to get to 1kOhm (2x 2kOhm, 3x 3kOhm, etc.)?

author: magic
author_rank: Super Contributor
timestamp: March 15, 2022, 01:05:07 pm
content: Same thing.2kΩ has sqrt(2) more noise than 1kΩ. Two equal noise sources mixed equally average out and end up sqrt(2) less than each of them.1kΩ is about 4nV/rtHz at room temperature, by the way.For unequal resistors, you treat the circuit as two noise voltage sources mixed by noiseless resistors. Attenuate each noise source by its corresponding resistive division ratio and RMS sum them (calculate sqrt(N₁²+N₂²)). The result should be the same as the noise of a single resistor equivalent to their parallel combination.Bottom line: you can't escape Johnson by cheating.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 15, 2022, 07:25:41 pm
content: Quote from: Evan.Cornell on March 15, 2022, 12:51:09 pmFor resistors there is no benefit, but for amplifiers it is.When two identical amplifiers are connected in parallel, the internal noise of the resulting amplifier is with 3dB smaller than the noise of a single amplifier. You get 3 dB less internal noise each time you double the number of parallel amplifiers. This is valid for internal uncorrelated (random) noise only, for example it will not reduce the mains hum noises.

author: TimFox
author_rank: Super Contributor
timestamp: March 15, 2022, 07:30:20 pm
content: Parallel devices (not resistors) is a common technique for reducing noise from low-impedance sources. If you parallelNBJTs, the noise voltage density decreases and the noise current density increases (both byN1/2). In a resistor, the noise current or voltage is the same noise power source, but at audio the two noise densities in a BJT are (almost) uncorrelated.

author: ejeffrey
author_rank: Super Contributor
timestamp: March 16, 2022, 03:52:25 am
content: Available noise power density from any passive circuit is just kT or -174 dBm/Hz. Doesn't matter if it is a micro-ohm or megaohm, whether it is a single resistor or a complex RLC network. The actual magnitude of current and voltage noise depend on the impedance, but two networks with the same impedance will have the same noise.
Concerning Parallax NES sockets - Page 1
Forum section: electronics / projects

author: slateraptor
author_rank: Frequent Contributor
timestamp: November 22, 2011, 11:18:09 am
content: http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/nintendo/List/0/SortField/4/ProductID/522/Default.aspxandhttp://www.parallax.com/Portals/0/Downloads/docs/prod/compshop/NES%20socket_larger.jpgFYI, if you specify a 1.2mm hole for the socket's footprint per the linked pdf, you'll be beating yourself with a broomstick when your PCB arrives and the sockets don't fit. 2mm should do the trick.

author: Balaur
author_rank: Unknown
timestamp: November 22, 2011, 12:07:57 pm
content: Well, it looks like the linked pinout indicates the pin diameter, and not the hole diameter. In these conditions, it's absolutely normal that the pin will not fit, especially considering the hole plating if applicable.(The pinout also indicates the mounting hole diameter, and this could be the source of the confusion).It's better to be on the generous side when sizing holes.Cheers,Dan

author: slateraptor
author_rank: Frequent Contributor
timestamp: November 22, 2011, 10:46:46 pm
content: Quote from: Balaur on November 22, 2011, 12:07:57 pmThat's easy to say when you already know that a 1.2mm hole won't work.The fact of the matter is the diagram itself is non-standard and misleading: the terminology "mounting hole" is used in two places, which led me to believe that this was a combined pinout/footprint as opposed to a combined pinout/mechanical top-view cutaway.

author: vk6zgo
author_rank: Super Contributor
timestamp: November 23, 2011, 12:39:13 am
content: In one of my recent jobs they never worked out that if you make a hole in a panel the exact size & then powdercoat the panel,the screw(or whatever) won't fit.We had to drill all these holes out to a bit bigger on almost every occasion.VK6ZGO
Concord security panel codes retrieval from EEPROM - Page 1
Forum section: electronics / projects

author: risquate
author_rank: Newbie
timestamp: June 16, 2021, 11:10:26 pm
content: Thanks latentsematincs for the great post and details on the same subject. This forum doesn't allow to comment there as it is too old post.I followed everything to the letter but had no luck. My Concord panel is older circa year 2003 and I noticed that the EEPROM chip is located in the upper right corner of the PCB board whereas most of the pics posted online show it in the middle slightly to the left. Maybe the software is different for older boards as well and the location of the codes is at different places. I managed to dump the whole EEPROM content and viewed it with Hexdump32 viewer. Couldn't find anything that makes sense at locations 994, 995 , ... etc.Attached is the dump of my EEPROM. You have to view it with Hex viewer to make sense of it. "Hexdump32" is free and easy to use. You can open it with a text editor as well but most of it (not all) will be non readable characters.If someone has experience with older models like mine than I'll appreciate some additional info.Thanks in advance.

author: Manul
author_rank: Super Contributor
timestamp: June 17, 2021, 12:31:01 am
content: Just a natural question, is this 24LC256? Why the size of the dump is 153068 bytes? There is no eeprom with such size. Maybe something is wrong with dump procedure?

author: amyk
author_rank: Super Contributor
timestamp: June 17, 2021, 01:20:27 am
content: For a second I thought this would be about the supersonic jet...I agree that something isn't right with that dump. There's plausible code-looking bits in there, scattered among lots of FF blocks. Areas of FF are normal on a non-full EEPROM as that's the default erased/blank state, but usually firmware isn't so fragmented like this.

author: risquate
author_rank: Newbie
timestamp: June 17, 2021, 02:09:47 am
content: Yes. I found a bug in the dumping program. Fixed now. Attached is the dump in friendly .txt format so that you don't need hex viewer to view it.

author: risquate
author_rank: Newbie
timestamp: June 17, 2021, 02:41:19 am
content: Hurray !!!! Success !!! Previous dump was corrupted by the Hex viewer. Attached is the correct one in.txt format. I managed to find 4 codes that all work. Marked them aa, bb, cc, dd (small caps) in the file. This is the only modification I did to protect my real codes. The real codes were at those locations. I know that aa is the Master Code and dd is the Installer code. Not sure what codes bb and cc are but I don't care at this point. The location of the codes is certainly different than the ones mentioned in other postings online. As I said my system is an older version of Concord circa year 2003. Hope this will help other users.
Condenser microphone with highly resistive diaphragm - Page 1
Forum section: electronics / projects

author: Bill Rolph
author_rank: Newbie
timestamp: February 24, 2023, 07:11:43 pm
content: I have just finished building a set of electrostatic speakers and am interested in measuring their performance. Lacking any sort of calibrated microphone I have been looking into alternate methods of performing the measurement and had the idea to use the diaphragm of the speaker as essentially the diaphragm of a condenser microphone, allowing direct measurement of the diaphragm displacement. The issue is that condenser microphones have a low resistivity metallic coating on the diaphragm, while on my speakers the coating (Licron Cystal) has a surface resistivity between 10e6 and 10e9 ohms. This high resitivity traps charge (relative to audio frequencies) in the diaphragm, which is necessary for a speaker but to my understanding antithetical to typical condenser microphone operation. That said, I am generally unfamiliar with microphones so there may be some sort of arrangement that will work. Has anyone got any ideas? Or, alternatively, any suggestions for other ways of measuring the diaphragm displacement? Reflecting a laser off the diaphragm and measuring the beam's movement seems like a promising avenue.

author: jonpaul
author_rank: Super Contributor
timestamp: February 24, 2023, 07:54:26 pm
content: cannt work

author: Marco
author_rank: Super Contributor
timestamp: February 24, 2023, 09:15:04 pm
content: Too many unknowns with the charge distribution for capacitive sensing.Sure, you can measure displacement with a laser. It will only tell you if it's linear though, not the real response. Just buy a reference microphone and a decent USB sound card.
Condenser microphones vs MEMS microphones - Page 1
Forum section: electronics / projects

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 19, 2025, 12:47:34 am
content: How do modern condenser microphones compare to MEMS microphones in terms of performance? I'm under the impression that condenser microphones are better since they cost a lot more than MEMS microphones and need an external preamp and ADC that increases cost further. But then you can get multiple MEMS microphones for the same cost and then use a DSP to combine them as a phased array. Given similar final parts cost, which one would be more likely to perform better?

author: Benta
author_rank: Super Contributor
timestamp: January 19, 2025, 01:13:52 am
content: No comparison.The MEMS mikes are made for minimum size and cost and usually for mobile phones, where sound quality is no issue (the digital compression will make it sound lousy anyway).Condenser mikes are (usually) for real audio, with responses going to perhaps 40 kHz and very low distortion.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 19, 2025, 01:28:16 am
content: Quote from: NiHaoMike on January 19, 2025, 12:47:34 amI suggest looking at respective datasheets to figure it out.Beyond the intrinsic characteristics, such as distortion figures and bandwidth, one major difference is the capture pattern, given the shape and sheer size of the MEMS ones, which have a small opening.The dynamic range is also usually significantly lower with MEMS, but again, don't take my word for it, go grab some datasheets and compare.For the capture pattern, I guess it may be possible to design a microphone made of multiple MEMS microphones arranged and processed in a way that reproduces the pattern of a typical large condenser microphone. That could be a nice challenge, if you have solid notions of acoustics.But the limited dynamic range and noise floor may still be redhibitory. Just my 2 cents.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 19, 2025, 04:49:25 am
content: I think MEMs microphones are condenser mics. They're really good for their size but can't do as well as a larger diaphragm mic. OTOH, there are a few with crazy high bandwidth, like well over 100 kHz!

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 20, 2025, 05:07:14 am
content: https://www.instructables.com/DIY-Large-Diaphragm-True-Condenser-Microphone-Caps/That article claims that a circle is a suboptimal shape for a microphone, is that really true? Additionally, is the given design going to have any hope of performing well? Seems like it could make a low cost condenser phased array microphone.
Conducted emissions CISPR 22 power output - Page 1
Forum section: electronics / projects

author: dpape
author_rank: Contributor
timestamp: November 07, 2018, 10:48:11 am
content: Hello,I'm finishing the design of a linux board which contains various peripherals (USB, Ethernet, ...)and I'm now doing some pre-compliance conducted emissions testing on the workbench. Thisis a telecomunications product for the EU so I'm using the CISPR22 standard for conductedemissions.The board is fed with 5VDC power input but also has a 12VDC @ 500mA power output (DC DC step-up).I'm now not sure how I'm supposed to connect the LISN and which maximum levels to use. I don'tfeel that this is a 'telecommunications port' but I don't think this is a 'mains' terminal either.Can anybody shed some light on this?Kind regards,Daan

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 07, 2018, 10:50:52 am
content: What would connect to it? Is it, say, replacing an external wall-wart or something?Tim

author: dpape
author_rank: Contributor
timestamp: November 07, 2018, 10:57:33 am
content: The 12V power output will supply power to one of the peripherals of the DUT. Forexample a ticket printer wich needs 12V input.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 07, 2018, 01:44:40 pm
content: Then I would guess it counts as another comm pair, since it's in a loop with them.If you specify a type of e.g. ticket printer, of known cable length and placement, then you can say "all of this is my equipment" and test it as a whole. But that's a no-no if it's unknown cable length and such.Tim

author: dpape
author_rank: Contributor
timestamp: November 07, 2018, 02:28:18 pm
content: Hi Tim,Thank you for the reply. The type of ticket printer and cable length is unknown. I'll just test it with the 5 uH LISN just as it would be a comm port.Kind regards,Daan
Conducting research for an electronics prototyping related project. - Page 1
Forum section: electronics / projects

author: Sagitarrius
author_rank: Newbie
timestamp: July 05, 2023, 01:02:16 pm
content: I am working on a product that can help people who DIY electronics (mainly targetted towards amateurs who are new to DIY). To help figure out what features I need to include I have constructed a survey which I am hoping as many of you can answer! Feel free to leave feedback on my ideas (see top of google forms).https://forms.gle/ZL4mGnNDX4YNbgBD8

author: liaifat85
author_rank: Regular Contributor
timestamp: July 08, 2023, 07:45:24 am
content: Filled up the form. Thanks.

author: ebastler
author_rank: Super Contributor
timestamp: July 10, 2023, 07:07:22 am
content: Just tried the link, but it says the form has been locked and no longer accepts any input. Hope you got the data you were looking for.
Conductive clear paint? - Page 1
Forum section: electronics / projects

author: kevyk
author_rank: Contributor
timestamp: November 14, 2016, 06:54:39 pm
content: Hi. Does anyone know if there is such a thing as a paint or adhesive that is both conductive (low tens to 100's of ohms perhaps) and is transparent or slightly opaque? I need to paint on a conductor (for touch) that, ideally will not obscure the object it is painted on too much or at all. Thanks!

author: IanB
author_rank: Super Contributor
timestamp: November 14, 2016, 07:12:26 pm
content: I think conductive paint usually contains fine particles of silver or carbon. I think it unlikely that anything transparent could be made conductive.

author: kevyk
author_rank: Contributor
timestamp: November 14, 2016, 07:21:16 pm
content: That was what I was thinking too. I was wondering if anyone has ever seen or worked with anything that is transparent or semi-transparent yet conductive that can be painted onto a surface.

author: Fungus
author_rank: Super Contributor
timestamp: November 14, 2016, 07:23:10 pm
content: Touch sensors can go underneath, too.

author: kevyk
author_rank: Contributor
timestamp: November 14, 2016, 07:25:41 pm
content: Unfortunately not. The object is about 1 inch thick and I'd like to use capacitive sensing if that is possible (with a conductive paint). Alternatively I would use an optical sensor or an RF sensor but I'd like to see if I can start with just clear conductive paint if that exists.

author: ChristopherN
author_rank: Unknown
timestamp: November 14, 2016, 07:40:09 pm
content: I only know ITO and other coatings that can be applied to glas. I don't think that you can use those as a paint.It seems that you can get ITO coated film/foil:http://www.polyic.com/products/polytcr.htmlhttps://www.aliexpress.com/item/1000pcs-A4-210-297mm-0-125mm-transparent-ITO-film-ITO-conducting-film-For-Electroluminescent-Product/32295259893.html?spm=2114.40010508.4.7.GECWsqOther options could be to cover the whole structure in a fine wire mesh.

author: ChristopherN
author_rank: Unknown
timestamp: November 14, 2016, 07:42:40 pm
content: Found something else, seems you can get clear conductive ink from Henkel.You can search for LOCTITE ECI 5000 E&C SeriesI can't find a price for it, so it could be expensive.

author: kevyk
author_rank: Contributor
timestamp: November 14, 2016, 07:45:40 pm
content: Now that ROCKS Chris! Thank you so much.I looked at Henkel but I somehow missed that.

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 14, 2016, 08:28:05 pm
content: Orgaconhttp://www.agfa.com/sp/global/en/internet/main/solutions/orgacon_electronic_materials/index.jsp
Conductive epoxy assembly - beginner question/advice request - Page 1
Forum section: electronics / projects

author: wb0gaz
author_rank: Frequent Contributor
timestamp: August 07, 2019, 02:21:32 pm
content: Hello - I am faced with installing a 0402 package SMD resistor into an existing HP RF assembly (called a test port coupler, part of a vector network analyzer test set) whose existing thin-film resistor was destroyed due to application of excess RF power at some point in the past. The coupler is too expensive to simply replace, so I'm seeking to repair it, at least enough to get it to be serviceable. The HP part number is 5086-7489 and there are images online (if you remove the top of the gold cover which is attached with ten Torx screws, inside near the main (large) test port connector is a small white circuit board.)The small circuit board in the coupler near the test port connector uses a ceramic (or some other exotic material) substrate. The traces on the substrate are gold (or gold plated). In a few places a resistor is actually printed onto the substrate (I think this is called a "thin film" resistor), and the dimensions of the (former) thin-film resistor which was destroyed and the adjacent gold/plated traces (visible under a toy binocular microscope) will accommodate a 0402 package thin film resistor, but with little clearance. I attached such a resistor (of approximately the correct value, which is known) with a tiny dab of (regular) epoxy onto the end of a wooden toothpick, temporarily pressed the resistor into position, and verified that the RF assembly functions (at least sufficiently) so that I'm now considering how to mount the resistor permanently.The confines of the component around the resistor are too small to permit soldering, and the small circuit board cannot practically be removed from the test port coupler housing, so it needs to be repaired in place. For these reasons, I am thinking attachment with silver-based conductive epoxy might be a suitable solution. MG Chemicals 8330S claims "extreme" thermal and electrical conductivity (that would be good to minimize further electrical impairments from this fix) and long working time (before hardening), but the material itself is expensive, so I don't want to head down that path without some confidence I'm approaching this properly and with some practice on a piece of perf or prototyping board and some cheap/low cost conductive epoxy, so I can get the feel of the material and components before delving into the coupler for permanent installation.So, I am looking for advice from someone that has hands-on experience working with conductive epoxy and tiny components in confined spaces, preferably around RF/microwave devices.Thanks very much for any advice, pointers or comments,Dave
Conductive material with large skin depth? (translucent to RF) - Page 1
Forum section: electronics / projects

author: Plasmateur
author_rank: Regular Contributor
timestamp: August 08, 2018, 03:57:18 pm
content: I'm not sure such a material exists, so I'm asking if anyone might be aware of it.The conductive material would have an effectively large skin depth so a very thin layer of it would still allow some amount of RF to propagate through it.I'm not sure how cellphone screens work (some kind of capacitive response?). Is this material similar to what I'm looking for?

author: duak
author_rank: Super Contributor
timestamp: August 08, 2018, 05:30:29 pm
content: Have a look at Aquadag - it's a colloidal graphite solution that can be applied to a surface like a paint to form a conductive surface. If this is too leaky, there are various other solutions of metals and other compounds that are used for EMC shielding of non-conductive enclosures. Henkel comes to mind as a supplier.I think a metal like Indium is deposited on touch screens to form the conductors. If it's thin enough it's invisible but still sufficiently conductive.Cheers,

author: Plasmateur
author_rank: Regular Contributor
timestamp: August 08, 2018, 07:09:06 pm
content: Sweet! Thank you so much!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 08, 2018, 07:30:48 pm
content: How conductive?ITO isn't very. It's just good enough for passing around signals to TFT transistors or capacitive touch sensing, but not something you can wire a power supply with.You may also be able to take advantage of polarization and such. A horizontal mesh screen is transparent one way, reflective the other.Tim
Conductive Polymer Aluminum Solid Capacitor -vs- MLC Capacitors in HV LDO - Page 1
Forum section: electronics / projects

author: beaker353
author_rank: Unknown
timestamp: January 03, 2016, 05:32:28 am
content: I'm working on a little power supply'ish project that keeps on getting pushed onto the "back burner" and then brought back to the "front burner" when time becomes available. In the project I'm using a Linear LT3086 high voltage LDO that has programmable current limit and parallel capabilities. Pretty slick little (literally) unit. In the docs it specs 10uF bypass caps on the output and input to maintain stability. It specifically says you CAN you ceramics, but not that you NEED to. As I'm running this pretty high voltage (31.2V in for a 30.7V out) the DC bias effect is quite substantial for MLC caps in the 10uF range. I've been looking into the conductive polymer aluminum solid capacitor and started to wonder if I could substitute this for the MLC caps. The load is going to be a very constant load and will not have large or quick changes in current draw. Any words of wisdom or suggestions? Thanks!-EM

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 03, 2016, 02:46:57 pm
content: They don't give a stability diagram unfortunately, but the datasheet does insist:- 1mA minimum load- 10uF min Cout- 100mohm max ESRAnything that meets that spec will do. You might need two 4.7uF 50V (1206 or 1210) X7R to get there, or one aluminum polymer. Yes, polymer should definitely be suitable here.Tim

author: beaker353
author_rank: Unknown
timestamp: January 04, 2016, 05:23:53 am
content: Thanks T3sl4co1l! I figured it would be compatible for my application, but didn't know if there was any "traps for young players" as Dave would say. Choosing the ideal type of cap for each application seems to be a bit of an art that isn't as straight forward as I wish it was. Further more, it's really not covered very much at all in my EET classes. I've serviced/modified/designed enough over the years to have learned some basic rules-of-thumb, but I still wish I knew more technical theory as to why...The more I know, the more I know I don't know...-EM
conerting a JST XH connector to board to board - Page 1
Forum section: electronics / projects

author: unknown_h
author_rank: Contributor
timestamp: May 13, 2022, 02:39:35 pm
content: Fells like a chasing a bit of red hearing, but I trying to figure out if you are able to get a female header for the JST XH connector that would allow for board to board connection. I have a situation where I need a pcb (it should be light enough I hope) to held by 2 of JST xh connectors by a product I am unable change or modify in any way.Any help would be greatly appreciated.

author: Zoli
author_rank: Frequent Contributor
timestamp: May 13, 2022, 03:39:42 pm
content: Workaround: crimp solid wire in the contacts; it can be bent, if necessary for the installation. A little bit of experimentation can go a long wayOTOH I'm not aware of the existence of the female sockets(PCB) or male connectors(wire) in the XH(clones) series.Have fun!

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 13, 2022, 04:33:18 pm
content: this may be of inspiration ?https://www.thingiverse.com/thing:5201441

author: thm_w
author_rank: Super Contributor
timestamp: May 13, 2022, 09:59:25 pm
content: Quote from: Zoli on May 13, 2022, 03:39:42 pmWire connectors:https://www.aliexpress.com/item/4000478657432.htmlPCB sockets I haven't seen.

author: inse
author_rank: Super Contributor
timestamp: May 14, 2022, 06:25:02 am
content: Did you try how the XH mates with a standard 2.54mm/0.1" socket strip?As there is little chance of reversing your piggy back PCB, you could get along this way...

author: jpanhalt
author_rank: Super Contributor
timestamp: May 14, 2022, 09:09:06 am
content: JQ are interchangeable and may help:https://www.jst.com/products/automotive-connectors/jq-connector/

author: tooki
author_rank: Super Contributor
timestamp: May 14, 2022, 03:51:47 pm
content: Quote from: inse on May 14, 2022, 06:25:02 amXH is 2.50mm, so beyond a few pins, they won’t mate at all.

author: tooki
author_rank: Super Contributor
timestamp: May 14, 2022, 03:55:21 pm
content: Quote from: jpanhalt on May 14, 2022, 09:09:06 amThis. ^^^JST has the annoying habit of giving compatible connectors with different functions (e.g. wire-to-board vs board-to-board, or crimp vs IDC) entirely different series names, rather than unifying them under a single name. And then they only inconsistently make reference to compatibility with the “other” series, like how the JQ mentions compatibility with XH on its datasheet, but not the other way around!
Confidence Level for Datasheet Values - Page 1
Forum section: electronics / projects

author: luky315
author_rank: Regular Contributor
timestamp: May 08, 2014, 12:04:45 pm
content: Is it correct that the IC manufacturers use "only" 95% confidence level for the Min/Max specifications in the datasheet? I know from one manufacturer that they use 95%, but someone else mentioned that 3 Sigma (=99% confidence level) is standard.Where can I find more informations?

author: dannyf
author_rank: Super Contributor
timestamp: May 08, 2014, 12:26:01 pm
content: It is an undefined term so it is up to the manufacturers. No "standard" to speak of.

author: Someone
author_rank: Super Contributor
timestamp: May 09, 2014, 12:11:49 am
content: The min/max values can form a contract of supply, so you can reject the parts that do not meet the specifications. Manufacturers deal with this in varying ways from taking back parts for testing and refund/resupply or just ignoring you!

author: Fsck
author_rank: Super Contributor
timestamp: May 09, 2014, 12:42:52 am
content: Quote from: dannyf on May 08, 2014, 12:26:01 pm^. you'd have to ask each manufacturer.
Configuring K point to keep module active - Page 1
Forum section: electronics / projects

author: ioncube
author_rank: Newbie
timestamp: October 07, 2025, 09:35:09 pm
content: This modulehas both charging & stepping up circuit for 18650 batteriesAccording to specs following x2 points are importantQuoteMy module is powering an emergency light that is configured to auto start in darkness (I have used a separate DO capable LDR module) It works, however, because of 2] point the module becomes offline in daytimeif not connected to external supplyvia type-C portHow can I keep module active using K-terminal even if module is not connected to external supply?
Confirmation on dimension of next batch uCurrents - Page 1
Forum section: electronics / projects

author: timgiles
author_rank: Regular Contributor
timestamp: March 29, 2016, 09:54:06 am
content: Hi,This is kinda technical - admittedly not the most electronic technical question - but - am I right in thinking that the uCurrent (if ordered today) has the same dimensions as is currently specced in the BOM?Altronics H0205 case - 82mm x 54mm (x30mm high - not important for me)I have made up a new electronics case - see attached and I need to know how big the uCurrent is, to see if I can also squeeze in my component tester.For those that are interested, the bag is an Ikea UPPTÄCKA briefcase and the foam is Kaizen foam - made up of lots of individual layers you cut through and peel back. Used this on 5 different cases from small to large flight case for a 8 inch telescope and related astronomy kit :-) Amazing stuff.Thanks Tim
Conformal Coating on specific components - Page 1
Forum section: electronics / projects

author: psam27
author_rank: Newbie
timestamp: June 01, 2018, 02:19:02 pm
content: Hi all,New to the forum. Does anyone know if conformal coating can be applied to inductors (mostly smd), and if so if there is any effect on the operation/life span of said component?Any help is greatly appreciatedPanos

author: elecman14
author_rank: Unknown
timestamp: June 01, 2018, 02:36:20 pm
content: Conformal coating should have no effect on the inductor(s)

author: sdouble
author_rank: Frequent Contributor
timestamp: June 01, 2018, 07:51:59 pm
content: depending on the power dissipated in the inductor, the conformal coating might be an issue. It typically reduces the heat transfer from the SMD o the outter world.

author: psam27
author_rank: Newbie
timestamp: June 04, 2018, 05:56:47 am
content: Thank you sdouble for the info. Heat management is very important in my case so this answers my question.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 04, 2018, 12:25:38 pm
content: Note that some conformal coatings have good thermal conductivity and may be appropriate for this use. One example:http://www.cast-coat.com/cc3-343.htmlIf your board has connectors, conformal coating may give you all kinds of headaches though.

author: psam27
author_rank: Newbie
timestamp: June 04, 2018, 01:32:46 pm
content: Thanks for the suggestion SiliconWizard.
conformal coating, that can easily, fully be removed? - Page 1
Forum section: electronics / projects

author: Chendy
author_rank: Contributor
timestamp: November 04, 2016, 01:01:27 pm
content: Hi,wondering if people knew a readily available conformal coating. But that also can be removed without too much hassle (so boards can be repaired). I dont need full submersion.. Maybe a Silcone based product?thanks

author: cat87
author_rank: Regular Contributor
timestamp: November 04, 2016, 01:13:15 pm
content: There are some "water" based conformal coatings. The reason for the "" is that it contains other co-solvents besides water. The main thing is that it provides adequate protection against harsh conditions (dust, moisture, etc) and can easily be removed mechanically (it flakes off quite easily) or it can be removed using some IPA. Another nice thing about it, it fluoresced under UV light, so that uncoated patches can be easily identified by the Quality control. Unfortunately I can't remember how it's called.Maybe this might be of some help...(looks similar to the one I remember)http://www.electrolube.com/news/2015/01/14/electrolube%E2%80%99s-water-based-conformal-coating-products-in-demand-after-reach-nmp-restrictions/

author: DTJ
author_rank: Super Contributor
timestamp: November 04, 2016, 01:32:53 pm
content: Similar to what Cat suggested:http://www.sensongroup.com/senson-tek/productsCan be removed with Methylated spirits or IPA.

author: Chendy
author_rank: Contributor
timestamp: November 04, 2016, 03:18:27 pm
content: Thanks guys,For clarity, the main hazard risk is spilling of water / beer / drink over consumer electronics...

author: DTJ
author_rank: Super Contributor
timestamp: November 04, 2016, 03:44:31 pm
content: That senson stuff is pretty good. You can really slobber it on if you want.It can be soldered through if needed.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: November 04, 2016, 06:46:32 pm
content: Krylon Electronic Coating was/is nothing more than Krylon Clear spray. It works well, though not as good as the expensive mil grade stuff like Humiseal, and can be removed with common solvents, or just soldered through.

author: helius
author_rank: Super Contributor
timestamp: November 04, 2016, 07:00:24 pm
content: I recently bought MG Chemicals 422B for this purpose. The smell is pretty bad and it takes a long time to cure, but it seems flexible and easily removable.
Confused about the LM334 - Page 1
Forum section: electronics / projects

author: m12lrpv
author_rank: Regular Contributor
timestamp: April 23, 2012, 11:01:43 pm
content: In Dave's power supply he has used the LM334 as a minimum load for the regulator.I would have to go back and look but I think he did that based on it providing a constant current across the voltage adjustment range.I have also noticed LTspice simulates it as providing a constant current regardless of the input voltage.While working through the datasheet I have noticed that the formula for determining the set resistor is voltage dependant so the current must vary with voltage. Yet the general understanding seems to be that this is not the case.So i'm confused as to what the real performance of this part is. From the datasheet it would seem that for varying voltages you may as well just dispense with the LM334 and just keep the set resistor (with the value increased a bit) to set a minimum load.I would experiment with it but the only one I have is soldered into a circuit

author: amspire
author_rank: Super Contributor
timestamp: April 23, 2012, 11:21:14 pm
content: Quote from: m12lrpv on April 23, 2012, 11:01:43 pmNo it is not. The equation for the current out of the LM334 isISET= (227 uV/deg K)/RSETSo the current is temperature dependant, but not voltage dependant.Richard.

author: m12lrpv
author_rank: Regular Contributor
timestamp: April 24, 2012, 12:00:38 am
content: My bad. I was reading Vr as VinSometimes you just need someone else to take a look for you to pick whatever obvious thing it is that you're missing.Thanks.
Confused about this datasheet. INA139 - Page 1
Forum section: electronics / projects

author: fc3000
author_rank: Regular Contributor
timestamp: September 27, 2023, 10:55:28 am
content: Hi all.I am using a INA139 in my project.As i was studying the datasheet, cannot understand the chart below.The output error is both negative and positive value!!Please could you explain how to read the chart.Regards.This is the full datasheet:https://www.ti.com/lit/ds/symlink/ina169.pdf

author: Psi
author_rank: Super Contributor
timestamp: September 27, 2023, 11:13:01 am
content: Not sure I understand your question.Error can be positive or negative. Above the correct value or below the correct value.In this case, as Vin gets lower the error becomes more negative.

author: fc3000
author_rank: Regular Contributor
timestamp: September 27, 2023, 12:34:37 pm
content: Hi. Thank you for the reply.So, are you saying that the error is a deviation from the perfect output?Regards.

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 27, 2023, 01:37:41 pm
content: Exactly.If nominal output is i.e. 1V, that's the deviation over it, based on input voltage and working temperature.

author: fc3000
author_rank: Regular Contributor
timestamp: September 27, 2023, 02:22:51 pm
content: OK got it now!Regards

author: Terry Bites
author_rank: Super Contributor
timestamp: September 27, 2023, 05:59:31 pm
content: Vin=(Vin+ - Vin-) is the voltage across the shunt, Is*Rs. Vin is referenced to supply voltage and the voltage across the load.All these factors and temperature will lead to error terms. Most sense amps are not all that precise because the market doesn't demand it it.Battery charging, motor shunts etc...There are exceptions of course.