hybridfree/eevblog-posts huggingface dataset:
Sharing a PC motherboard PWM signal - Page 1
Forum section: electronics / projects

author: ttl
author_rank: Newbie
timestamp: June 03, 2015, 08:23:20 am
content: Hello,I'm trying to control the speed of 5 PC fans via PWM (all at the same speed). My motherboard only supports PWM signals on the CPU FAN header, but it has 4 other 4-pin headers which don't actually work as intended (they have voltage control).So what I'm thinking is that I can connect the PWM signal to all 5 fans, and connect each fan's tachometer to a motherboard header, and a separate 12V/GND from the power supply. I have attached a rude schematic of what I'm trying to do.Can you tell me if this will work properly, before I start crimping this mess?Thanks.

author: Psi
author_rank: Super Contributor
timestamp: June 03, 2015, 08:28:58 am
content: I cant see any problem doing that.

author: Mr.B
author_rank: Unknown
timestamp: June 03, 2015, 08:40:54 am
content: Yes, that will work.I have done it before.However, be aware that all the fans speeds are dependant upon what the motherboard thinks the CPU temperature is.This may be quite fine for your requirements...

author: ttl
author_rank: Newbie
timestamp: June 03, 2015, 09:00:45 am
content: Quote from: Mr.B on June 03, 2015, 08:40:54 amThat's exactly what I want.Thanks!

author: Kevman
author_rank: Regular Contributor
timestamp: June 03, 2015, 11:32:08 am
content: Did you check the BIOS settings page? Many motherboards have an option in the BIOS to switch fans between 3-pin (voltage) and 4-pin (PWM) mode.

author: Mr.B
author_rank: Unknown
timestamp: June 03, 2015, 07:02:28 pm
content: Quote from: Kevman on June 03, 2015, 11:32:08 amGood point, however the OPs drawing would indicate that the 4 headers concerned are only 3 pin.
Sharing a sense resistor between multiple devices - Page 1
Forum section: electronics / projects

author: Electr0nicus
author_rank: Regular Contributor
timestamp: February 04, 2015, 12:09:47 pm
content: HiI currently designing a circuit which uses a LTC2946 power monitor IC and a LT4363 High voltage surge stopper. The LT4363 will also be PWM'ed using it's shutdown Pin and the Highside N- channel power mosfet which is already used for the surge and overcurrent limiting functions. After calculating the component values for the sense resistor, which both devices use, I get the same value for both sense resistors, for my particular application. So that made me thinking, if it will be a good idea to use only a single sense resistor, and connect both devices to it. With a kelvin connection of course.While it looks perfectly fine in theory, I'm not 100% sure if it will be also perform as expected in practice. Also if it is good practice anyway. Maybe someone with more experience on that field can give me an advice.Thanks,Gregor.
Sharing ADC and GPIO PADs that supports 5V tolerant - Page 1
Forum section: electronics / projects

author: Fred573
author_rank: Newbie
timestamp: October 11, 2023, 03:24:38 am
content: Hello everyone,I have a question that I would like to share with you:I am currently working on a project where I want to share the input PAD of an ADC with the GPIO's PAD. The main purpose behind this is to save costs. The GPIO PAD supports 5V tolerance, while the ADC only allows a maximum input voltage of 3.6V. I have implemented a switch (transmission gate) between the ADC and the PAD, which allows me to turn off the ADC when it is not in use. However, I have a concern regarding the situation where the PAD voltage is 5V, as it could potentially conduct through the PMOS of the switch and damage the ADC. Could someone please guide me on how to address this issue?Thank you all for your assistance.Best regards,Fred

author: PCB.Wiz
author_rank: Super Contributor
timestamp: October 11, 2023, 03:52:11 am
content: Is the ADC on the chip, or external ?Usually on-chip ADCs with 5V tolerant pins, are also 5V tolerant, even if they can only measure up to 3.3V Vcc.If the ADC is external and the pin can drive to 5V, you will need protection.The simplest can be a series resistor, and you could add an analog switch if micro-power is needed, or if you need other ADC pins reading.(clamp currents can disturb adjacent ADC pins )
Sharing damn simple cheap alternative to expensive Hakko FG-100 thermometer - Page 1
Forum section: electronics / projects

author: mcinque
author_rank: Unknown
timestamp: February 23, 2019, 03:54:34 pm
content: Nothing particularly fancy or complicated here, something that even a monkey can do...Instead spending $$$ for the overpriced Hakko FG-100 to check solder irons calibration, I guess it's damn cheap (and damn easy) to use this kind of pcb and a meter with K thermocouple input and purchase only the cheap 191-212 hakko sensors.I found this way better than simply using a K thermocouple on the iron tip because the Hakko sensor is much more stable and I can get repeatable readings and the sensor thermocouple is housed inside a small metal cage to avoid adding metals to the bimetallic junction while measuring tin temperature, falsing the readings.- connections are made with1.8mm RC battery contacts(females are soldered to the pcb, males are used to "hold" the Hakko sensor, the sensor height is optimal)- pcb is attachedMaybe someone can find this useful, even if it's so damn simple that anyone can do it.

author: GreyWoolfe
author_rank: Unknown
timestamp: February 23, 2019, 07:27:31 pm
content: Why not get a Hakko FG-100 knockoff? Under $12 USD from China. They even work fairly well. I have one.https://www.ebay.com/itm/FG-100-Soldering-Iron-Tip-Thermometer-Temperature-Tester-LCD-Display-0-700-DIY/192691374192?hash=item2cdd4d0870:g:iUIAAOSwGWJcUW1S:rk:3:pf:1&frcectupt=true

author: mcinque
author_rank: Unknown
timestamp: February 23, 2019, 08:13:24 pm
content: Quote from: GreyWoolfe on February 23, 2019, 07:27:31 pmMostly because of calibration: you can't calibrate some versions as they are manufactured by different "companies" each one with a different PCBs inside, attached examples, one is without calibration. Since I can't know which kind of fake I'm buying, and since I already have a digital thermometer with K thermocouple input, I preferred to choose this way.EDIT: maybe you can add calibration to the second pcb by adding VR1 but I don't like this kind of incertainess and the crappy soldering and flux residues.

author: amyk
author_rank: Super Contributor
timestamp: February 23, 2019, 08:47:34 pm
content: The temperature-voltage dependency of a thermocouple is exact, that does not need calibration after it leaves the factory.

author: mcinque
author_rank: Unknown
timestamp: February 23, 2019, 09:09:54 pm
content: Indeed, but the voltmeter reading the thermocouple value won't require a basic calibration? Mostly because we're reading millivolts.
Sharing my decryption of schematic of a broken toy cat - Page 1
Forum section: electronics / projects

author: NightMoth
author_rank: Contributor
timestamp: January 07, 2025, 07:10:49 am
content: HelloHere I’m sharing my decryption of schematic of a broken toy cat.Just for documenting. Also somebody may be curious about circuity of this type of toys.It is a toy cat that blinks its eyes, wags its tail and makes “cat sounds” (mew, purring etc.) when you touch it and closes its eyes and makes “snoring” sounds when you put it on its back.Also this toy has “voice repeating” mode, and I discovered this mode only after its disassembling and schematic decryption.I never even knew this mode was available! it looks like this toy was already broken when I bought it...The failure was that the toy stopped responding to touch.According to my understanding, failed module is the NY9T004A-008a Touch Key controller, all other modules works as expected (even without datasheet for AB23BP1W98, all its functions seems very clear).Circuit board still can be used as pulse generator or as voice repeating toy.Datasheets:NY9T004AS8-008A (Touch Key and LED controller)https://www.nyquest.com.tw/upload/2020_03_273/NY_Touch*Standard*Code_v1%602_EN.pdfT25S40 (4MBit FLASH)https://datasheet4u.com/datasheet-pdf/Bright%20Moon%20Semiconductor/T25S40/pdf.php?id=1142666TRA9118A (Motor driver)https://www.chipsourcetek.com/DataSheet/TRA9118A.pdf"JL" AB23BP1W98 (Microcontroller?)Can’t find datasheet
Sharing RExt between multiple MAX6971 LED drivers? - Page 1
Forum section: electronics / projects

author: MsJaye
author_rank: Contributor
timestamp: August 12, 2014, 02:50:51 pm
content: Hey there,I'm designing something using 16 MAX6971 LED drivers, each of which will drive 16 LEDs. The MAX6971 sets the current per LED using an external resistor, RExt. I'm wondering if I can use the same resistor, or possibly a pot, as RExt for all 16 of the MAX6971s, and thus use it as an overall brightness control for the array? (I'll already be using PWM on the array for other purposes, so having a simple overall brightness adjustment would be nice.)I realise that the value for the shared RExt will probably not be the same as for a single MAX6971 for an equivalent drive current. I'm more wondering if there are reasons this won't work, or would be a bad idea?Datasheet here:http://datasheets.maximintegrated.com/en/ds/MAX6971.pdfThanks,Jaye.

author: fcb
author_rank: Super Contributor
timestamp: August 12, 2014, 03:32:25 pm
content: I'd be careful about paralleling th Rset pin's on multple devices.Use a current mirror (with 16 outputs...), or perhaps 4x4 output current mirrors instead of the resistors.

author: jackbrouno
author_rank: Newbie
timestamp: August 13, 2014, 11:42:12 am
content: What if i only have an resistors

author: German_EE
author_rank: Super Contributor
timestamp: August 13, 2014, 02:16:52 pm
content: It doesn't work (I tried it a few years ago). The brightness depends on the current of ONE 6971 running through a resistor. Using a digital potentiometer with either SPI or I2C is one solution especially if you give all potentiometers the same address.

author: dannyf
author_rank: Super Contributor
timestamp: August 13, 2014, 03:27:05 pm
content: Without knowing the mechanism Maxim used to program the current via Rset, you probably cannot know for sure.However, other chips that use a resistor to program have tend to utilize a current drive on the resistor and sense the voltage drop on the resistor to program.If I were you, I would measure the voltage across the resistor and try to see if it is done via current or voltage.If the programming is done via voltage, you can probably set a divider and tie all the Rset pins to that divider, via isolation resistors.If the programming is done via current, you may use current mirrors to do it. This can be done fairly easily and inexpensively, via either discrete parts or ICs (like those 5-20ma transmitters).But I would start with measuring the voltage / current over a range of resistor values.

author: MsJaye
author_rank: Contributor
timestamp: August 13, 2014, 05:11:08 pm
content: Quote from: dannyf on August 13, 2014, 03:27:05 pmMany thanks, this was just the kind of advice I was looking for.Jaye.
Sharks with frikken' (acoustic) laser beams on their heads. - Page 1
Forum section: electronics / projects

author: ehughes
author_rank: Frequent Contributor
timestamp: September 28, 2016, 10:56:15 pm
content: If any of you are in the NYC area this weekend, I will be hosting an exhibit focused on the the science of sound at Maker Fairehttp://circuitmaker.com/blog/world-maker-faire-2016-sharks-with-frikken-acoustic-laser-beams-on-theirStop by! We have lots of electronics with LEDs (a cool retro styled video game) as well as the acoustics exhibits. And yes, we we have a small acoustic laser to demo.

author: xjordanx
author_rank: Contributor
timestamp: October 26, 2016, 04:00:03 pm
content: Sorry I couldn't be there to visit you again this year Eli, how was it?I hope to be back there next year!
Sharp distance sensor GP2Y0D340K replacement part  - Page 1
Forum section: electronics / projects

author: axelockero
author_rank: Newbie
timestamp: March 29, 2015, 01:06:17 pm
content: Hi!I'm currently working on a micro sumo robot and had thought about using sharps GP2Y0D340K(http://www.sharpsme.com/download/gp2y0d340k-epdf) distance sensor as this sensor would be small enough and still have enough range.Today when I was searching for parts at different re-sellers I noticed that the sensor is no longer manufactured. Therefor I would be really happy if anyone knows a similar unit. I have been searching for another sensor but haven't really found any similar with a minimum range of 400 mm and dimension within 20*15*15 mm.Thanks in advance!

author: wraper
author_rank: Unknown
timestamp: March 29, 2015, 01:42:20 pm
content: There is no real substitute actually AFAIK. I made a substantial research about such sensors about 2 years ago. When I was in similar need for another sharp sensors which do have analog output (measures actual distance), I'll bought them from AVNET EU warehouse pretending to be business customer. Otherwise they won't sell me, and that was basically a single place where they were left. I bought fixed distance sensors too at pololu but they were 5 and 10 cm ones. Sharp dropped production of their distance sensors but they are still available at some places, for example aliexpress:http://www.aliexpress.com/af/gp2y0d340k.html?SearchText=gp2y0d340k&CatId=0&shipCountry=lv&initiative_id=SB_20150329054146&isAffiliate=y&SortType=price_asc&filterCat=400103&groupsort=1

author: axelockero
author_rank: Newbie
timestamp: March 29, 2015, 02:00:27 pm
content: Thanks for the reply wrapper!I think I will try to use some other type of sensors or try to find them somewhere. But it's really a pity that they have ended their production as there are a lot of hobbyist still using them.

author: hli
author_rank: Frequent Contributor
timestamp: March 29, 2015, 08:25:36 pm
content: Strange, Sharp SME list their status as "production":http://www.sharpsme.com/optoelectronics/sensors/distance-measuring-sensors/GP2Y0D340K(although Farnell says "not produced anymore"). There are several other distance sensors by Sharp that have this reach, but they are all larger than what you need (e.g. GP2Y0A710K0F, GP2Y0D02YK0F, GP2Y0A21YK0F, GP2Y0A02YK0F - the last two are close)

author: axelockero
author_rank: Newbie
timestamp: March 30, 2015, 09:14:26 am
content: I have a pair of GP2Y0A21YK0F laying around from an old project and it seams like they could fit if I remove the mounting holes on the sensors and glue them in place instead.
Sharp Memory LCD - Page 1
Forum section: electronics / projects

author: ingep
author_rank: Unknown
timestamp: July 27, 2015, 01:34:47 pm
content: Hi,I'm planning to use a Sharp Memory LCD in my next hobby projectI would like to use the LS013B7DH01 1.26" (the same display as in the original Pebble watch I think). But it uses a zebra strip connection. Does anyone have experience with this display, or know where to get zebra strips?My other option is to use the LS013B7DH03 1.28", with an flat flex connector, but it has lower resolution...http://eu.mouser.com/new/Sharpsma/sharpmemorylcd/Any help is appreciated

author: will9twl
author_rank: Contributor
timestamp: July 29, 2015, 06:12:27 am
content: Hi ingepIf it's a hobby project, I wouldn't recommend LS013B7DH01 because it is difficult to get a zebra connector and soldering might be challenging.I used the LS013B7DH03 with this breakout (https://www.tindie.com/products/kuzyatech/sharp-memory-lcd-breakout-a2/) and developed the driver code using a STM32F411-Nucleo board.
Sheathed/Shrouded 4mm Banana Jacks on Keithley equipment - Page 1
Forum section: electronics / projects

author: Cicada
author_rank: Regular Contributor
timestamp: March 23, 2022, 12:33:39 pm
content: HiThe images below shows Keithley equipment internals. I would like to know what brand sheathed/shrouded 4mm Banana Jacks are used in Keithley equipment.https://xdevs.com/doc/Keithley/6485/img/k6485_tops.jpgSource pagehttps://xdevs.com/fix/kei6485/https://xdevs.com/doc/Keithley/2400/photo/xDevs.com/_TIM5465.jpgSource pagehttps://xdevs.com/fix/kei2400/This looks close to what I see in the pictures. But it is not exactly the same.https://www.digikey.co.za/en/products/detail/cal-test-electronics/CT2912-2/6005453So I wonder what part (brand/part number) Keithley uses in their equipment. I would like to know. My assumption is that it would be one of the best brands out there.Can anyone tell me.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 23, 2022, 01:43:58 pm
content: Multi-Contact Staubli? SEB4 or SEB4 RseriesBut push in... I dunno if thats up to scratch.

author: Cicada
author_rank: Regular Contributor
timestamp: March 23, 2022, 03:50:19 pm
content: Quote from: Terry Bites on March 23, 2022, 01:43:58 pmFantastic. This forum amazes me every time.Thanks "Terry Bites"I also wondered about the push-in/press-fit feature. Not sure if that is the best. But it seems to be working for Keithley.Page 74 of the catalog.https://www.staubli.com/global/en/electrical-connectors/products/t-m-products/t-m-downloads/catalogs.htmlPicture attached.

author: tooki
author_rank: Super Contributor
timestamp: March 24, 2022, 02:13:38 pm
content: Quote from: Cicada on March 23, 2022, 03:50:19 pmI think it works well if you can maintain high dimensional accuracy of the mounting holes during manufacturing. And I assume there are certain hardness requirements for the front panel material.I’d be leery of using them in, say, cheap plastic housings drilled using a hand drill. (For those, the kind with a nut on the back are decidedly better.) But in something mass-produced in high quality, like Keithley’s front panels, or in metal drilled with a drill press and the optimum drill diameter, it’s a nice solution.They sell a specific tool for inserting them, by the way.
Sheet for milling front/back panels - Page 1
Forum section: electronics / projects

author: plazma
author_rank: Frequent Contributor
timestamp: August 17, 2017, 05:41:04 pm
content: I would like to mill front and back panels for aluminium housings like this one:I found aluminium composite sheet from eBay. Have anyone tried to mill these with PCB milling machines?http://www.ebay.com/itm/SHEETS-OF-ALUMINIUM-COMPOSITE-WHITE-BLACK-BLUE-BRUSHED-FINISH-COLOURS-A4-A3/171470410676Any other sources for bulk panel sheets? I would need brushed aluminium on black plastic.

author: Fred27
author_rank: Unknown
timestamp: August 17, 2017, 06:24:10 pm
content: They mill very nicely on a low end CNC mill/router. I've no idea of the exact capabilities of your PCB mill though.

author: jmelson
author_rank: Super Contributor
timestamp: August 17, 2017, 08:36:08 pm
content: I made something from an anodized extruded housing with sheet covers, similar to your picture. I had a HECK of a time with it. Each cover needed two DB9-size cutouts in it, and it ate about one 1/8" solid carbide end mill per cover. The anodizing was so hard it was like trying to mill a grinding wheel. I normally use those solid carbide end mills for dozens of panels with many holes in them without breakage.My plan, if I ever had to do that again was to mill 2024 or 6061 sheet and then apply a label to match the color of the box, and toss the anodized covers.Jon
Shield connection - Page 1
Forum section: electronics / projects

author: ezalys
author_rank: Frequent Contributor
timestamp: November 30, 2021, 12:25:14 am
content: For connecting DC connectors to a cryostat, it's quite common to bring all the DC lines out through a shielded cable and then out to a break-out box. The cryostat's electrical surface is extended through the cable shield out to the breakout box chassis -- this much makes sense. It's common on these breakout boxes to have a pair of switches for each BNC connector -- one that shorts the pin to ground, and the other floats the shield of the BNC connector completely or grounds the shield to an internal ground. A banana connector on the back allows one to short the internal ground to the chassis. The signals broken out do not extend beyond maybe 100 Hz or so, if that. The internal connections go to high impedance loads in the cryostat.Does this whole scheme defeat the point of the shield? For good EMI shielding, I would expect that you want the BNC shield shorted _all around_ to the chassis, rather than being isolated and then connected through a switch. This arrangement seems to me to add quite a bit of inductance to the path to the chassis. How should I analyze this shielding/grounding arrangement to understand the compromises made?

author: Terry Bites
author_rank: Super Contributor
timestamp: December 01, 2021, 04:46:44 pm
content: The ground float switch is there in case you have a "ground loop".https://www.edn.com/understanding-grounding-shielding-and-guarding-in-high-impedance-applications/
Shielded interface cables for devices with high PE current - Page 1
Forum section: electronics / projects

author: Leonelf
author_rank: Contributor
timestamp: July 01, 2024, 11:04:12 am
content: Hi!I'm currently working on adding a communications interface to a power device. The problem is, that the power device has a very high PE current, as it's an industrial device with different standards than consumer equipment. When using shielded cables (shield grounded to chassis), a share of this PE current is transmitted over the shield, making it fail conducted emissions tests on these interfaces, as they PE current originates from the input filtering of the device.Are there certain best practices or measures that enable using shielded cables on such high-PE-current devices? Industrial Ethernet and ProfiNET etc. all use shielded cable, but they often control such high power devices; How do they do that? My fallback idea would be total isolation and a floating non-shielded cable...

author: moffy
author_rank: Super Contributor
timestamp: July 01, 2024, 11:12:07 am
content: To avoid this issue the shield should only be connected at one end and left open at the other.

author: Leonelf
author_rank: Contributor
timestamp: July 01, 2024, 11:20:37 am
content: I've read of this approach, but found an article multiple times, countering this:https://www.emcstandards.co.uk/cable-shield-grounded-at-one-end-onlyHas this practice been deprecated?

author: moffy
author_rank: Super Contributor
timestamp: July 01, 2024, 11:52:20 am
content: Try just a single ended ground and see what the result is, it will certainly stop the current flow while still providing electrostatic shielding, magnetic shielding/protection is best done by twisted pairs as in CAT5 cable etc.
Shielding a ACS758 Current Sensor ? - Page 1
Forum section: electronics / projects

author: Swaroop 21
author_rank: Regular Contributor
timestamp: January 17, 2025, 05:29:05 pm
content: I am planning to use a ACS758 Current Sensor for measuring AC Current. I saw a few videos on YouTube that these hall effect sensors are sensitive to magnetic interference. I experimented with ACS712 Sensor and its readings were affected by a magnetized tip of a screwdriver. The sensor will be mounted in a enclosure in the Breaker Box. So how do i shield it and with what material ? And I will have a mains transformer powering the circuit so will it affect it too ?

author: thm_w
author_rank: Super Contributor
timestamp: January 17, 2025, 11:04:51 pm
content: How large is the box, test again with the screwdriver at the distance of the box size.Are you talking about 60Hz mains transformer? You can get shielded ones.

author: Smokey
author_rank: Super Contributor
timestamp: January 17, 2025, 11:24:21 pm
content: I have used Allegro hall sensors for current measurements a bunch. Some are more susceptible to stray fields than others (I'm looking at you ACS711 !)Space is your best bet. Keep everything away from the sensor, including other high current traces on the PCB.If you want to try shielding, have a look at muMetal.https://en.wikipedia.org/wiki/Mu-metal

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: January 18, 2025, 01:02:34 pm
content: You can check this PDF.https://www.allegromicro.com/-/media/files/application-notes/an26030-managing-external-magnetic-field-interference-acs71x-current-sensor-ics.pdf

author: woody
author_rank: Frequent Contributor
timestamp: January 18, 2025, 01:41:39 pm
content: Quote from: Swaroop 21 on January 17, 2025, 05:29:05 pmThey are. I found out the hard way a decade ago when I placed a relay next (1.5cm) to an ACS723. Complete disaster for my current measurement. Space and positioning is the solution I then used to solve this.In another design I did last year, also containing a relay and a current sensor, I used an MCS1802GS. This is a bit smarter in that it uses differential sensing which cancels out external magnetic influences. And indeed, that does work

author: BennoG
author_rank: Frequent Contributor
timestamp: January 18, 2025, 07:06:24 pm
content: Why not use a current transformer. Thes are more accurate and dont have problems with static magnetic fields.Benno
Shielding circuit with plastic magnetic sheet ? - Page 1
Forum section: electronics / projects

author: BravoV
author_rank: Super Contributor
timestamp: March 04, 2018, 09:37:27 am
content: As the elastic magnetic sheet is available quite cheaply with relatively large surface area, wonder if a circuit is encased or fully shielded with these sheets will reduce EMI / RFI exposure ?Any insight will be appreciated.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 04, 2018, 01:34:47 pm
content: Y'mean the fridge magnet stuff, or actual soft magnet stuff?Tim

author: plazma
author_rank: Frequent Contributor
timestamp: March 04, 2018, 01:59:58 pm
content: Should you use flexible ferrite sheet instead?

author: ocset
author_rank: Super Contributor
timestamp: March 04, 2018, 02:57:27 pm
content: QuoteNo i dont think you can do effective B field shielding with thin pieces of sheet. -Think of the thick foam things they put on the walls of EMC chambers...they are thick foam, and not thin sheet.If its thin sheet, then for E field shielding it should be metallic.

author: BravoV
author_rank: Super Contributor
timestamp: March 05, 2018, 08:34:18 am
content: Quote from: T3sl4co1l on March 04, 2018, 01:34:47 pmLike this for example.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 05, 2018, 12:24:01 pm
content: Ah. Yeah, no... that's magnetized, hard ferrite. Permeability of about air.Or, more correctly: a modest (average) permeability, but only when you drive it hard enough to remagnetize it; in which case it will quickly melt, because all that magnetic energy is lost as hysteresis.There may actually be a little (small signal) permeability, no idea. It's not going to be useful though...There's no fundamental difference between that, and the stuff that's useful to us -- ferrite of either kind is cheap, just mix it in and go. But they have to make a metric shitton of it, to get the price that low. An easily-magnetized (soft) ferrite isn't very useful to consumers, so it's not made in that kind of quantity.Tim
Shielding in plastic enclosure: conductive coating, tape/fabric, foil, or what? - Page 1
Forum section: electronics / projects

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: February 22, 2020, 12:46:46 am
content: The conductive paint on the inside of an Apple IIe's plastic enclosure got me thinking: what's the best way of shielding devices in plastic enclosures if your production runs are so small thatconductive coatingsare not cost-effective due to the time and complexity?Nickel-copper conductive fabricswere once used for this but I haven't seen a device with them in a while. They're also available in tape form.What do people end up using for thing like homebrew test equipment?

author: thm_w
author_rank: Super Contributor
timestamp: February 22, 2020, 01:10:42 am
content: Why do you say not cost-effective due to time and complexity? You can buy them in small volume in spray cans:https://www.eevblog.com/forum/oshw/open-source-hw-rf-signal-generator/msg2900484/#msg2900484The other option is copper foil or aluminum foil tape, first one you can solder to relatively easily.
Shielding material in RS equipment - Page 1
Forum section: electronics / projects

author: PartialDischarge
author_rank: Super Contributor
timestamp: August 11, 2018, 10:24:21 am
content: Yesterday I was butchering a RS equipment, nothing interesting, and noticed that modules inside have a 3 layer metal shielding, aluminum, copper and other one. Most probably it is a sheet of high nickel content for its magnetic properties, it also looks silvery shiny same as nickel, but I'm not sure. Anyone? Is it a commercial product?

author: rhb
author_rank: Super Contributor
timestamp: August 11, 2018, 06:54:20 pm
content: Mumetal is what is typically used. It's almost pure nickel, so quite expensive.

author: DaJMasta
author_rank: Super Contributor
timestamp: August 11, 2018, 07:00:58 pm
content: The shine and tarnish on the leftmost layer in the first pic look like silver to me, and I believe I've seen the same as plating on milled RF blocks in other R&S equipment before (6GHz board in an SMIQ). The parts that are exposed to air get a brown tarnish, and the overall color of the metal is VERY bright, much lighter than aluminum, nickel, steel, etc.Never tested it, but that's what I suspect.

author: PartialDischarge
author_rank: Super Contributor
timestamp: August 12, 2018, 04:02:10 pm
content: Well, it seems that the metal in question definitively has nickel.I decided to dust off my chem lab and also looked into my old books. I used to like quantitative chemistry and one of the books I have is a translation from a 1895 book by a german chemist, Alexander Classen, that describes detection of many metals. Books like these are found no moreThe method is as follows:-Dissolve the metal with nitric acid to give a greenish solution, Ni(NO3)2 (Tube 1)-Adding ammonia in excess gives a blue solution, as the complex nitrate nickelammonia is formed (Tube 2)-The blue solution is bleached by the addition of KCN (tube 3, not shaken completely, KCN crystals at bottom)
Shielding portable battery operated device with plastic enclosure - Page 1
Forum section: electronics / projects

author: DanielRehak
author_rank: Contributor
timestamp: January 31, 2025, 04:05:58 pm
content: Hello,we have a device that is operated in strong electric/magnetic field environment. This field induces high voltage on our cable shields (20kV and higher). Cable shields are currently not connected anywhere on our PCB board. Our device have enclosure made from plastic, non conductive material.Our device is battery operated, so connecting to ground wire (green and yellow wire - at least in my country in Europe) from electrical outlet cannot be done.I am thinking of connecting this to negative pin of our Lithium Ion battery (3S - 12.6V) and maybe introducing some high frequency filter in between. Is this good idea?Our device GND is seperated from battery negative pin, as there are charging MCUs in between. So I think I should not introduce the noise coming from shield into our device ground reference.

author: thm_w
author_rank: Super Contributor
timestamp: February 01, 2025, 01:02:46 am
content: From this video:If you are stuck with plastic enclosure, then can try connecting shield to PCB, with or without capacitor.Or you can try changing enclosure to metal, or applying a conductive layer (paint or tape), and connecting the shield to that.

author: mtwieg
author_rank: Frequent Contributor
timestamp: February 02, 2025, 05:07:25 pm
content: Quote from: DanielRehak on January 31, 2025, 04:05:58 pmYou're going to have to describe the setup a bit more clearly... does this device have any cables to external equipment? If not, what cables are you referring to?20kV of induced voltage is somewhat hard to believe, especially if it's within a small space with no external connections.

author: DanielRehak
author_rank: Contributor
timestamp: February 03, 2025, 09:39:05 am
content: Quote from: thm_w on February 01, 2025, 01:02:46 amThanks for the video, I will watch it. Could you specify in what part of the PCB you would connect it? I can connect to PCB GND or Battery negative terminal (they are different nets due to voltage regulators)

author: DanielRehak
author_rank: Contributor
timestamp: February 03, 2025, 09:45:33 am
content: Quote from: mtwieg on February 02, 2025, 05:07:25 pmThere are 5m external cables with shielding connecting to another part of the device - basically a sensor that is operated in high electromagnetic field.Regarding 20 kV being hard to believe - I believe I might not have explained properly. The 20 kV is as static charge potential measured by static voltmeter and this value is normal. It can get up to 16 kV on human body when conditions are right (low humidity, syntetic clothing).
Shift register for driving 20 x reed relays (SIP-1A05)? - Page 1
Forum section: electronics / projects

author: onesixright
author_rank: Frequent Contributor
timestamp: January 04, 2017, 08:15:24 pm
content: Hiya All,Lets start with best wishes, that all may happen what you wish for and that in good health!Quick question. I need to drive 20 reed relays (SIP-1A05). I was thinking of using 3 x 74HC595, but that leaves me with a few pins not used. Not a big issue, but I rather have 1 component that has 20 (or 2x 10), and on top i prefer to drive it viaI2C.Any thoughts?Much obliged!

author: rstofer
author_rank: Super Contributor
timestamp: January 04, 2017, 09:14:08 pm
content: Sure! A couple of MCP23017 I/O Expanders ought to do ithttp://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf
Shift registers for my project - Page 1
Forum section: electronics / projects

author: chikenlover
author_rank: Newbie
timestamp: May 20, 2015, 05:44:26 pm
content: Hello everyone!I have made a project with ''tri-state'' shift registers, I'm using 74HC595. Too late I have realised that I need to keep few pins in active states and few in HI-Z state (interchangeable). Does anyone know some similar shift registers that offer the oportunity to change any pin to HI-Z (not all together)?

author: oPossum
author_rank: Super Contributor
timestamp: May 20, 2015, 06:28:41 pm
content: There are SPI and IIC port expanders that can essentially tri-state outputs by changing them to an input as needed.MCP23017/MCP23S17 and many others.
Shipping QFP's - Page 1
Forum section: electronics / projects

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 28, 2023, 06:05:45 pm
content: Hi there,I have a tray full of new old stock QFP components that I need to sell and ship. Some individually and some multiples of the same chip.The chips have been stored in a few jedec trays, so thus far I've just been cutting the trays and shipping them like that. But obviously this isn't feasible to do with a single one or two chip order, as I'll run out of jedec tray to use.I'm looking for the trays here in canada, but I can't seem to find any on digikey, or any packaging solution that will keep the QFP leads safe and keep them out of harms way in shipping.How should I go about doing this? I'm not too familiar with electronic component packaging, so I'm stuck here.

author: HwAoRrDk
author_rank: Super Contributor
timestamp: October 28, 2023, 08:07:03 pm
content: RS's solution for shipping individual QFP chips is to put them in a little cardboard 'book' lined with anti-static foam, fastened closed with tape, then placed in a static-shielded bag.The cardboard stops the leads getting bent and the foam cushions the chip while being clamped inside the 'book'.I don't know where they get them, so you could probably fashion your own from a sheet of cardboard and anti-static foam. Just glue the foam to the card with spray adhesive, cut into appropriate sizes and fold.

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 29, 2023, 01:55:28 am
content: Quote from: HwAoRrDk on October 28, 2023, 08:07:03 pmThanks I'll give that a try.

author: ataradov
author_rank: Super Contributor
timestamp: October 29, 2023, 03:42:03 am
content: There are boxes like this available in cardboardhttps://www.esdshop.eu/catalog/product/1759-ESD-boxes-with-foam-135x50x20mm/and plastichttps://www.weidinger.eu/en/esd-protection/esd-storage-and-transport/esd-small-parts-containers/wl21022. Those links are just random examples I found, there are lots of versions of them.I've seen Mouser use both, no idea how they decide which one to use.

author: Dan123456
author_rank: Regular Contributor
timestamp: October 29, 2023, 05:41:48 am
content: Are you selling them in a proper professional capability? Or more an hobby supply / eBay type deal?Only reason I ask is if it is the latter, you can just sticky tape them to a piece of cardboard etc. and then make sure that is packaged well (from what I have seen, usually inside of a ziplock bag as some secondary protection just in case the tape were to let go).I have received a few like this in the past from online sellers and they have always made it to me safe and sound so farThat said, I absolutely recognise this is not an option / isn’t a good look in a professional setting hence my original question

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 29, 2023, 06:41:38 pm
content: Quote from: Dan123456 on October 29, 2023, 05:41:48 amyes it's just a hobby supply type thing. The chips I'm selling are definitely not used in a professional capacity anymore
shockey diode - Page 1
Forum section: electronics / projects

author: pete g
author_rank: Regular Contributor
timestamp: March 19, 2024, 06:45:56 pm
content: are sd101b and 1n5711 interchangeable?

author: bostonman
author_rank: Super Contributor
timestamp: March 19, 2024, 07:03:31 pm
content: Think you need to be more specific about which parameters you're looking for.Immediately I see forward current is 30mA versus 15mA.

author: wasedadoc
author_rank: Super Contributor
timestamp: March 19, 2024, 07:35:45 pm
content: BTW neither are "shockey" diodes. Nor Shockley diodes.https://en.wikipedia.org/wiki/Shockley_diodeThey are Schottky diodes.https://en.wikipedia.org/wiki/Schottky_diode
Short circuit detection algorithm that doesn't false trigger? - Page 1
Forum section: electronics / projects

author: e100
author_rank: Frequent Contributor
timestamp: June 17, 2018, 05:26:36 pm
content: I'm trying to make a power supply that has short circuit detection, but ignores the brief current transient you typically get when charging up the decoupling caps on the device that is being powered. For inspiration I looked at the data sheets of various voltage regulators but these give little or no information on how this is implemented within the device.Currently to avoid false triggering I continuously calculate a rolling average of the current over a half second window. This seems to work ok on the bench. Is this the sort of algorithm used in commercial devices?

author: Phoenix
author_rank: Frequent Contributor
timestamp: June 18, 2018, 01:02:57 am
content: What sort of power supply is this? Most DC bench supplies have a constant current mode that effectively protects against short circuit.

author: e100
author_rank: Frequent Contributor
timestamp: June 18, 2018, 02:43:17 am
content: Quote from: Phoenix on June 18, 2018, 01:02:57 amIt's essentially a car battery with a solid state switch that powers a bunch of sensors at the end of 50 meters of cat5. There's a 0.2 ohm resistor in the low side that I use to measure the current with a microcontroller.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 18, 2018, 05:07:04 pm
content: Well, hoping that your PS has a current limiter for safety reasons, detecting a short-circuit condition may be as simple as monitoring the output voltage of your PS instead of monitoring the output current. If it's a 12V supply, you could set a threshold of 1V or 500 mV. Looks like a sure way of detecting a short.

author: donpetru
author_rank: Contributor
timestamp: June 18, 2018, 05:25:36 pm
content: In this case it would be useful to attach schematic because I think you have wrongly placed that 0.2 ohm resistor as a current sensor !!!

author: e100
author_rank: Frequent Contributor
timestamp: June 18, 2018, 06:53:45 pm
content: Quote from: donpetru on June 18, 2018, 05:25:36 pmThe car battery is in my garden, not a car so there's no grounded metalwork to warrant a high side shunt resistor.
Short circuit location with current - Page 1
Forum section: electronics / projects

author: fretless
author_rank: Contributor
timestamp: January 09, 2014, 07:48:34 pm
content: Hey guys,I have a phone that has its Vbattery rail shorted somewhere. I was thinking if it is safe to try and locate the short using 1A, maybe 2A of current. The short measures 0.3 ohms.

author: Rerouter
author_rank: Super Contributor
timestamp: January 09, 2014, 08:03:33 pm
content: and blow it up in the process with a 1.3W short on the 2A current, aim for 500mA, this gives you 150mV to trace it out with, while being a much smaller wattage

author: SeanB
author_rank: Super Contributor
timestamp: January 09, 2014, 08:04:11 pm
content: Try 0.5A first, and limit the voltage to 3v so that if the failed capacitor ( most likely suspect) blows open you do not fry the whole board. Feel for something warm, or use a thermal imager if you have, or an IR thermometer.

author: fretless
author_rank: Contributor
timestamp: January 09, 2014, 08:14:26 pm
content: I'v read somewhere that you can spray the entire board with freezer spray and the damaged component/trace will become apparent. However I'm worried that it may cause some damage because of thermal stress. Am I wrong?

author: zapta
author_rank: Super Contributor
timestamp: January 09, 2014, 08:34:16 pm
content: A thermal camera may help.

author: nctnico
author_rank: Super Contributor
timestamp: January 10, 2014, 01:35:06 am
content: I usually set a PSU to 1V (or less) and push current into a circuit. The short is easy to find with a multimeter. The short has the least voltage across it.

author: fretless
author_rank: Contributor
timestamp: January 12, 2014, 05:37:57 pm
content: If I were to spray parts of the board with freezer spray and then look for parts that defrost first to find the short, would 0,5 A be enough ( the short is 0.25 - 0.3 ohms) to spot the difference?

author: Ghydda
author_rank: Regular Contributor
timestamp: January 12, 2014, 07:17:51 pm
content: Quote from: fretless on January 12, 2014, 05:37:57 pmA short answer: maybe, it pretty much depends on how uneven the thermal mass of the populated board is. If is very uniform chances are good. If no, then things will defrost very unevenly regardless of you feeding in a quarter of a watt or not.But why not just try it anyways? Couldn't hurt.
Short Detector and stereo features on circuit boards - Page 1
Forum section: electronics / projects

author: limakan
author_rank: Newbie
timestamp: September 22, 2024, 08:10:04 am
content: The attached circuit diagram represents a Short Detector designed to detect short circuits in electronic circuit boards. The project involves the use of a NE555 timer configured in astable mode to generate a square wave signal. This signal is then passed through an LC filter circuit, which is tuned to a specific frequency for effective detection of short circuits. The filtered signal is further amplified using the LM358 operational amplifier to enhance the detection sensitivity and a notch rejection filter to 50Hz. The LTSpice simulation provides audio outputs (see wav output files)Is there a way to improve this circuit and add stereo features that should rely on asymmetrical current pulses (peaks in one direction compared to the DC average) and involve non-linear amplification of both the received signal and its inverted counterpart ? The goal is to produce a stereo pair of signals that can imply the current flow direction using stereo imaging.Do you have other improvements (synchronous detector..) ?I am looking to modify the circuit so that it can differentiate the direction of current flow by producing stereo output. This would involve creating asymmetrical signals for each channel (left and right) and introducing non-linear amplification. Thanks
Short length shielded cable+connector connection for about 20 signals - Page 1
Forum section: electronics / projects

author: daqq
author_rank: Super Contributor
timestamp: May 18, 2016, 07:28:20 am
content: Hi guys,I've got two devices that need to be connected using a shielded connection to prevent interference both ways - it's a nasty environment and it's a requirement. The distance between the two blocks is less than 7 cm.There are about 20 signals including power that need to be transferred between the two.I've been looking at shielded DSUB connectors, but the connector blocks are very bulky - they are 4cm or more long themselves, which is just impractical spacewise.Ideally there would be some IDC connector that would have built in shielding so I could just snap in this kind of cable on both ends:http://uk.farnell.com/3m/3517-40/ribbon-cable-40way-per-m/dp/8608636?ost=8608636&selectedCategoryId=&categoryNameResp=All%2BCategories&iscrfnonsku=falseDo you have any suggestions? This is a very low volume device, as such stuff that has to be soldered (but is not bulky) is OK.Thanks,David

author: unleashedko
author_rank: Newbie
timestamp: May 24, 2016, 02:27:32 am
content: I work at cable manufacturing facility and I can't say I've ever seen a shielded ribbon connector before, all of them I have seen are typically "plastic". Would it be possible to use connectors with a couple extra pins and attach the ribbon cable shield to those pins? Those pins could then be tied into your device grounds on each end. That would shield the majority of your conductors but you'd still be able to pick up interference at the connector pins. Maybe a metal shielding can of some sort to go around the connector housing on the device?You could also use shielded RJ45 connectors and Ethernet wire potentially, if you are willing to use more than connector per device. Or another option you could look into would be micro-D connectors and use some shielded cable and backshell. Similar pin outs to the larger D-sub connectors but in much smaller packages. Link to some popular ones below.http://glenair.com/micro_d/pdf/b/solder_cup_metal_shell_connectors.pdf