hybridfree/eevblog-posts huggingface dataset:
Multi-turn rotary encoder - Page 1
Forum section: electronics / projects

author: kazam
author_rank: Regular Contributor
timestamp: June 15, 2018, 09:59:25 am
content: Hi, I have an application where I need to be able to measure 100 turns of rotation of a small plastic shaft, diameter 6mm.Ideally I would like a 10k, 100 turn potentiometer. It needs to be absolute positioning. Accuracy is not critical.Searched the usual places but could only find 10 turn pots.Ideas, anyone?/K

author: ebastler
author_rank: Super Contributor
timestamp: June 15, 2018, 10:30:30 am
content: 100 turn pots are available, e.g. from Vishay:https://www.vishay.com/docs/32531/rp12multi-turn.pdf.Expensive, I‘m afraid... Or you could use a 10x reduction gear and a 10-turn pot.Do you need to just count full revolutions, or resolve angles within each full turn? Mechanical revolution counters would be the traditional solution if full revs are all you need:http://www.fargocontrols.com/counter/mechanical.htmlPersonally, I would prefer to move away from the requirement for absolute encoding if possible, and have a microcontroller monitor a cheap quadrature encoder all the time. This will require zeroing or otherwise initializing the position upon power-up, of course, which may or may not be feasible.

author: james_s
author_rank: Super Contributor
timestamp: June 17, 2018, 05:36:00 pm
content: You could use a small 10:1 gearbox to drive a 10 turn pot. There is probably something off the shelf that will do that, I do like encoders better than pots though.

author: Nusa
author_rank: Super Contributor
timestamp: June 17, 2018, 06:01:27 pm
content: A rotary encoder (title) and potentiometer (text) are different approaches. From what you've said, i'd lean toward an encoder as well. If the shaft turns rapidly or constantly/frequently, an optical encoder might be best.

author: abyrvalg
author_rank: Frequent Contributor
timestamp: June 18, 2018, 09:05:34 am
content: Linear pot + screw is another option
Multi vendor IC recommendation for inductor DCDC buck&boost - Page 1
Forum section: electronics / projects

author: Psi
author_rank: Super Contributor
timestamp: June 27, 2021, 12:11:13 pm
content: With the chip shortage I have decided to redesign one of my products before supply becomes an issue. It uses a linear part that is really nice but having only one vendor is making me nervous.Does anyone have any recommendations for jellybean DCDC ICs available from multiple companies with the following requirements- input 9-30V output 14V @ 3A (must be buck+boost / sepic)- Inductor based- 3A continues (without running at max temp)- Price isnotreally an issue (eg, chip must be under $7 in 100 volume but cheaper is obviously better.)- Ideally an intergraded driver, but I suspect for 3A it will need external fet.- Bonus points if it includes internal hardware for output current regulation.It will be used in a battery charger.It doesn't need to be "smart" at all, just pump 3A between two batteries when its on with under volt input limit and over current + over voltage output limit. I already have the external circuitry sorted for rev polarity issues etc..Any chip recommendations?Thanks in advance
Multi zone environment chamber - Page 1
Forum section: electronics / projects

author: qwaarjet
author_rank: Regular Contributor
timestamp: November 14, 2023, 06:39:56 pm
content: Does any one know of an environment chamber that can do -40 to 60c either with multiple test cells or individual small units that can be stacked. Only need about 0.5m^3 per cell. also water cooled and preferably run on 480vac.I'm setting a testing facility and we want run about 10 test simultaneously for "reasons" I can not use a single larger chamber. Smaller chamber typically are 120v and dump their heat to the air but with this number of chamber hvac starts becoming an issue. I have access to chilled water and would perfer to use that.

author: jbb
author_rank: Super Contributor
timestamp: November 14, 2023, 07:37:02 pm
content: No specific idea, but a useful search term might be ‘thermal shock chamber’ or similar(I’m now remembering the time I opened a chamber which hadn’t cooled down yet from an 85 deg C, 80% relative humidity test. Basically got instant rain right in front of my face…)Edit: in hindsight, that could have gone worse for me than a wet shirt. Check the humidity before you open, people!

author: qwaarjet
author_rank: Regular Contributor
timestamp: November 14, 2023, 07:47:18 pm
content: Yea planning a dry nitrogen purge to avoid that exact problem.
Multicard RFID spoofer - Page 1
Forum section: electronics / projects

author: jorenca
author_rank: Contributor
timestamp: January 02, 2016, 10:26:15 pm
content: Hi guys, first post here, I've been watching the blog (great stuff btw) for a while now and tought why not join the forum.I'm relatively new to EE and I'd be happy to get some feedback about the design of this little thing.It's a 125kHz RFID spoofer card. I tried to upgrade some (more basic) designs I've seen on the web so it would both support several card IDs (7 in this case) and not require a battery.The only 2 controllers I had in my parts bin were ATmega8 and ATtiny85, and considering the low-power requirements, I picked the ATtiny.I measured the max current induced in the card by the reader and got about 1.5mA(which, according to the ATTiny85 datasheet is insufficient for powering the controler running at 8MHz - the only suitable internal osc? and I couldn't spare pins for external crystal osc, it seems to work OK however after a second of charging the electrolytic capacitor)As I only had 3 spare pins for inputting the selected card ID, I binary encoded (is this the correct term?) the 7 buttons using the diode madness (bottom part of the schematic).Is there a better way to do this?Can the components count be reduced? I tought about using the internal controller clamping diodes, but had limited success doing so.Using the device is as follows:* Place the card near the RFID reader and wait until it start beeping (with no pitch change)* Press the button coresponding to the card ID you want to transmitVideo:https://youtu.be/QtRbtY0wWas

author: cponcsak
author_rank: Contributor
timestamp: January 03, 2016, 04:21:56 am
content: If you wanted to clean up your diodes, you could use a triple 4 input OR gate.http://www.ti.com/lit/ds/symlink/74act11802.pdf
Multichannel Audio System (2 x 24 Bit ADCs, 4 x 24 Bit DACs) based on BeagleBone - Page 1
Forum section: electronics / projects

author: henrix
author_rank: Newbie
timestamp: February 17, 2016, 12:04:24 pm
content: Hi,we've created a multichannel audio system based on the BeagleBone Black/Green and the AD1938 by Analog Devices Inc.The audio system is already up and running with a lowest possible latency of 3,2 ms (measured with oscilloscope).The whole project is open sourced.The full article with detailed audio system characteristics is publishedon our website.Moreover asmall articlecan be found on hackaday.io.Our next project goal is to use audio system as external USB device with the Linux USB audio gadget (g_audio).There are some ressources byTIandAnalog Devices.I've already compiled Linux with the USB audio gadget enabled.When I load the g_audio kernel module, I get an additional soundcard interface on the BBB and on my host PC, so the BBG is recognized as a sound device.My question is, how to I connect the audio codec driver with the USB audio gadget driver that the audiostream is directly routed to the audio codec?It would be great if somebody could help us with this subject.Thanks!

author: drewm1980
author_rank: Newbie
timestamp: May 08, 2016, 09:27:02 am
content: Cool project!I have an idea for a noise cancellation application as part of a musical instrument design. Basically I want to stick one or two earbuds and one or two condenser mics in the holes of a whistle/recorder/blockflute and see if I can electronically start/stop and retune the sound.Do you have boards available?Cheers,Andrew
Multichannel sine generating: DDS or DSP? - Page 1
Forum section: electronics / projects

author: Katanara
author_rank: Contributor
timestamp: April 19, 2022, 03:09:26 pm
content: Hi guys! I'm considering various ways of multichannel (3-4 sources) generation of a sine waves. The needful signal range is 50-100 kHz. At the current stage, I have an appropriate number of DDS (AD9834) with the ability to adjust the amplitude using a DAC (multichannel too). It works nice, but it doesn't seems the cheapest way. I'm interested in learning of DSP. Is it possible to replace several DDS with one low-cost DSP (like ADAU 1701)? With my specifical requirements: amplitude control from 0V (or close to that), the mentioned frequency range. And preferably low-costThank you for your attention!

author: b_force
author_rank: Super Contributor
timestamp: April 22, 2022, 09:33:04 am
content: The DSP you have in mind will work, but it won't go higher than 20kHz (even at higher samplerates).Besides, because of all the chip shortages, basically any DSP is out of stock
Multilayer Ceramic Cap Dielectric types - Page 1
Forum section: electronics / projects

author: Wilson__
author_rank: Frequent Contributor
timestamp: April 22, 2024, 09:39:16 pm
content: What Multilayer Ceramic CapDielectric typeshould be used for (a) by pass Cap for Li cellcharger IC(TP4065 for Vin/GND and Cell+/Gnd) andLDOMCP1700 (b) by pass for LDO Vin/Gnd, Vout/Gnd (c)LoRa Radio module (peak current 120mA) Vcc/Gnd. From Mouser, 10uF, 5V, non polar MLCC cap, there are X8L, X7R, X5R, X6S, X7T, X7S. TIA

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 23, 2024, 01:14:45 am
content: IDK what is intended for this exact cicuit but all of them you mentioned will work fine.(X8 of cause has to be better then X5).
Multilayer DIY Printed Circuit Boards - Page 1
Forum section: electronics / projects

author: Frantone
author_rank: Regular Contributor
timestamp: March 18, 2013, 07:08:08 am
content: A new thread By Request! Enjoy!To create the CuteUino prototypes I had to push the absolute limits of DIY printed circuit board density. In the final assembled form these raw circuit boards produce two different three-layer PCB's just 20mm square, and all hand made. Now, that is very small... and very cute indeed!To make hand made three-layer PCB's I made a sandwich of two single sided boards that would be aligned with the headers, and a copper foil inner ground plane layer was hand cut and soldered into the vias.My three layer hand made PCB package with lots of vias.http://www.frantone.com/designwritings/design_writings.html#cuteuino

author: Rerouter
author_rank: Super Contributor
timestamp: March 18, 2013, 07:22:01 am
content: give it 2 months and i envision a video from you on a DIY IC package at this rategreat work as usual fran,

author: peter.mitchell
author_rank: Super Contributor
timestamp: March 18, 2013, 08:38:31 am
content: TBH, im also quite impressed at how nicely the text "CuteUino " in the pour turned out

author: poorchava
author_rank: Super Contributor
timestamp: March 18, 2013, 08:39:11 am
content: That works. I have made 4 layer boards in the past. Just etch different layers on single side laminate, solder header pins, second layer, solder header pins and so on. The problem is the meniscus which forms around the header, which causes a gap between laminate layers. And having a cnc-drilled holes helps. It's actually best to drill a stack of raw laminate plates to maintain perfect hole alignment.

author: Rerouter
author_rank: Super Contributor
timestamp: March 18, 2013, 08:59:09 am
content: poorchava could you not technically get away with some low melting point solder paste or similar for hard layer to layer construction? using solder mask to leave only your pasted vias touching?

author: ecat
author_rank: Frequent Contributor
timestamp: March 18, 2013, 09:00:19 am
content: Nicely done Fran. Sweet little USB I/F idea too.I suppose it is actually quicker and easier to use copper foil vs etching a double sided + a single sided board. Which gives me an idea (don't laugh, it's in a strange place):If you cut the two tabs you are soldering to about 3 times longer, you can place the two boards together, wrap the tabs 180 degrees around to the bottom board and then do the soldering. No more solder joint between the boardsBut may need a dab of nail varnish to ensure the wrapped copper doesn't get torn away.

author: SeanB
author_rank: Super Contributor
timestamp: March 18, 2013, 05:49:51 pm
content: To handle the solder bump just back drill the upper layer of board to provide a place to put the solder joint. Only needs to be done on a few holes in this case, and then they will be flat.Very nice Fran, you are making a replacement for an old IBM mini look there, just need to get a stack of the aluminium cans that were used on the IBM logic, and a board with lots of via's on top and bottom in a pattern, then you can build IBM style.
Multimeter acts funny after measuring transformer secondary resistance - Page 1
Forum section: electronics / projects

author: TopLoser
author_rank: Unknown
timestamp: April 30, 2015, 12:21:19 am
content: Has anybody ever had a multimeter act 'odd' after measuring the resistance of a transformer secondary winding? Only temporary, the fault resets when switching to another measurement function. There must be some high voltage surge after the probes are disconnected, maybe enough to upset the input circuit?Yes I have asked for the test to be repeated using just a 220 ohm resistor, but I'm interested in what people might have experienced.

author: Monkeh
author_rank: Super Contributor
timestamp: April 30, 2015, 12:41:30 am
content: Can't say I have.. although it's not unusual for autoranging to go absolutely bonkers when presented with windings.

author: macboy
author_rank: Super Contributor
timestamp: April 30, 2015, 01:55:50 pm
content: I think you are right about the high voltage surge. Think about it: the meter measures resistance by putting a constant current through the DUT (transformer winding in this case) and measuring the voltage. When you remove the connection to the transformer, the current is interrupted suddenly. A transformer winding is a big inductor, and what happens when you change current quickly in an inductor?Try putting a snubber across the transformer winding, say a 10 ohm resistor in series with a 10 nF cap. This should not affect resistance readings since the cap blocks DC. Measure again. Do you get the same strange behavior from the meter? Probably not.

author: albert22
author_rank: Regular Contributor
timestamp: April 30, 2015, 04:35:40 pm
content: It happened to my fluke. But only when measuring windings not afterwards. Try disabling the auto range and selecting a suitable range for the measurement.

author: mushroom
author_rank: Regular Contributor
timestamp: April 30, 2015, 11:12:15 pm
content: Same problem while measuring (not after) only in autorange mode with a UT61E. The aurorange algorithm does not understand the inductive load, and turns the DUT + DMM into an oscillator (nice trace on the oscope).Could your DMM firmware crash ?
Multimeter backlight modification - Page 1
Forum section: electronics / projects

author: adras
author_rank: Regular Contributor
timestamp: August 15, 2015, 02:29:58 pm
content: Hello,I've got a multimeter which is based onFS9922. Unfortunatelly that thing has a horrible backlight control. It turns off after 10 seconds which makes it quite useless.I'm now wondering how I can modify it that the backlight is always turned on. Switching it would be cool, but I think the most easy way is to just have it always on when the multimeter is on as well.There's one interesting pin, LBOUT. My question is now, is it a good idea to connect that pin to VDDA? Or in general, how can I achieve that the backlight is always on when the multimeter is turned on?I hope you can help me

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 15, 2015, 03:29:45 pm
content: sounds easy enough, the link is not working though

author: adras
author_rank: Regular Contributor
timestamp: August 15, 2015, 05:04:53 pm
content: Link fixed, you can now see the datasheet there

author: Rostislav
author_rank: Contributor
timestamp: August 15, 2015, 10:05:40 pm
content: hi!button set with fixing for illumination. such as, eg:http://www.chipdip.ru/product/ps700l/ps. can you have schematic your multimeter?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 15, 2015, 10:50:05 pm
content: Hi,No need to modify the DMM, press the 'HOLD' button for more than 2 seconds.The datasheets says:Regards,Jay_Diddy_B

author: mariush
author_rank: Super Contributor
timestamp: August 15, 2015, 10:56:59 pm
content: Jay, the backlight will turn off after 10 seconds no matter what, it's built into the chip.To answer op's question, see the example circuit in the datasheet, you could hook a wire before the LED and after pressing HOLD for two seconds, the chip will send power through wire which you can detect with a microcontroller or some other chip (some kind of on/off switch etc which will only turn off when the meter is powered off).

author: onlooker
author_rank: Frequent Contributor
timestamp: August 15, 2015, 11:08:28 pm
content: Other than try to power the LED directly from VDDA as mentioned, VDD can also be used if OP is willing to replace the LED with a non-white one.

author: adras
author_rank: Regular Contributor
timestamp: August 19, 2015, 05:35:49 pm
content: Turned out that the pin goes HIGH to +3V. The actual voltage for the backlight panel is 6V so there's some boost circuit between the pins. I just searched for a pin which is always +3V and connected it to the backlight output pin.Now the display is always on, when the multimeter is powered.Thanks for your suggestions.
Multimeter Clock - Page 1
Forum section: electronics / projects

author: abbtech
author_rank: Contributor
timestamp: August 14, 2010, 10:27:33 pm
content: Thought you guys would get a kick out of this crazy clock.http://alan-parekh.com/projects/multimeter-clock-simpson-260/

author: Simon
author_rank: Unknown
timestamp: August 14, 2010, 10:51:55 pm
content: that's really interesting I might give it a shot some time
multimeter current fuses i2t? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: October 14, 2022, 07:22:24 am
content: so I need to replace some fuses in a 34401A, and I see HP has a special part # for it.When you look at fast blow fuses with the same rating, you can get the same thing with a bunch of different I2T ratings.If there is no I2T rating given, what should you choose?On one hand I think the fastest one, but on the other hand DMM often have a robust input protection network, so it might be impractical and unnecessary.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 14, 2022, 10:30:05 am
content: in my meters i put 3 amps fuses only, they are rated at 600voltsBut Keysight says 3 amp for the front panel and 7 amp for the inside one if i recall ... witch i find stupidI'm not using the sand filled ones, but i should in case of an overload, BUT for higher currents i work in voltages and shunts, instead of current, i never blow the fusesAnd the sad thing is, when the meter is calibrated, they normally put stickers on the case screws ... i asked them to put the stickers on the top casing, rear position.
Multimeter hack That may change the way you use your meter ....... - Page 1
Forum section: electronics / projects

author: Retro
author_rank: Newbie
timestamp: June 23, 2011, 12:39:13 am
content: This has to be the cheapest hack on the planet and one of the most useful.All because my probes were slipping, its that simple i just had to share it.The picture will explain everything..............Hope you Enjoy it....

author: ivan747
author_rank: Super Contributor
timestamp: June 23, 2011, 02:17:27 am
content: Now I can save $100 on some tweezer type multimeters. Wicked.

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 23, 2011, 03:09:14 am
content: I just hold my probes like I'm eating Chinese food. Chopsticks for the win.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 23, 2011, 05:19:38 am
content: i dont get it! how? i know that thing wont work for me.

author: bobski
author_rank: Contributor
timestamp: June 25, 2011, 05:43:29 pm
content: Hah. Interesting. I recently built a set of tweezer-probes for my multimeter.Thats a cheapie set of probes with the tips ground down to make the very points contact first (rather than the corner where the cone-taper starts) hot-glued to a re-bent IC puller and then shrink-wraped for additional durability. Some additional shrink wrap limits the exposed area of the probes. Finally, spiral-type wire wrap to keep the probe wires' stray capacitance stable (about 50 pF once the meter "warms up").

author: tekfan
author_rank: Frequent Contributor
timestamp: June 25, 2011, 06:44:34 pm
content: Now that's clever. I don't think I'll need tweesers though because I mostly just use trough hole components. Any ideas on how to probe the leads under a capacitor?

author: Unknown
author_rank: Unknown
timestamp: June 25, 2011, 07:06:38 pm
content: Quote from: tekfan on June 25, 2011, 06:44:34 pmFirst thing that came to mind is to modify the standard hook terminals as used in scope and DMM probes. The idea is to only retain the thin hook and replace the rest with thin wire. Variations of this could be atatched on tweezers.
MultiMeter Wall Mount Cases Free 3D Print Files - Page 1
Forum section: electronics / projects

author: billbyrd1945
author_rank: Regular Contributor
timestamp: March 01, 2022, 03:43:15 pm
content: I drew these up and printed them out. I think they came out pretty good. Feel free to use the attached files for printing your own. All I ask is that you post some pics.

author: Ranayna
author_rank: Super Contributor
timestamp: March 02, 2022, 03:12:51 pm
content: Zip them up, then you should be able to attach.But please do not upload GCODE. GCODE is printer and filament specific. What works for you will likely not work for someone else.

author: hli
author_rank: Frequent Contributor
timestamp: March 02, 2022, 04:38:47 pm
content: For my U1252B, I created an attachement so you can hang it onto a hook:https://www.prusaprinters.org/prints/117242-agilent-u1252b-u125x-hook-wall-mount. Might not be a stable as your cases, but you can take off the DMM without removing the leads.

author: floobydust
author_rank: Super Contributor
timestamp: March 02, 2022, 05:40:37 pm
content: There are also multimeter 3D parts (holder, stands, knobs) posted on MakerBot/Thingiverse. Good for getting ideas as well.Just search for fluke, ormultimeter holderor stand, case etc.

author: bob91343
author_rank: Super Contributor
timestamp: March 02, 2022, 05:58:53 pm
content: These holders are all well and good, but prevent use of the meter while in them. A few minor changes and you could have a holder that allows operation while holding.

author: billbyrd1945
author_rank: Regular Contributor
timestamp: March 02, 2022, 07:18:38 pm
content: Very nice!

author: billbyrd1945
author_rank: Regular Contributor
timestamp: March 02, 2022, 07:20:42 pm
content: The Fluke case is designedspecificallyfor using without removing from the case. Not so with the UNI-T. I made the Fluke one in two pieces so I wouldn't have to use supports. The UNI-T is one piece, just a place to store it above one's bench.
multipile MC14051B with single dataline - Page 1
Forum section: electronics / projects

author: hussamaldean
author_rank: Unknown
timestamp: August 30, 2019, 02:20:21 pm
content: Hi allI want to use 6 MC14051B with ATMEGA328P for upcoming project. but I am not sure how to connect those to the same data line. in another word, I want all 6 ICs connected to same digital pin (for example PB5).any guid to do such thing ?I am learning here btwregards

author: Rerouter
author_rank: Super Contributor
timestamp: August 30, 2019, 02:23:52 pm
content: Have all the outputs connect to that one data line, have all the A/B/C signals in parallel back to the micro, and then a separate inhibit signal to each chip to select which one you want active.

author: hussamaldean
author_rank: Unknown
timestamp: August 30, 2019, 02:32:02 pm
content: Quote from: Rerouter on August 30, 2019, 02:23:52 pmso, when inhibit is set to high, it will be HI-Z moderight?

author: Rerouter
author_rank: Super Contributor
timestamp: August 30, 2019, 02:39:29 pm
content: Yes, Correct

author: hussamaldean
author_rank: Unknown
timestamp: August 30, 2019, 02:40:28 pm
content: okthank you
Multipile output flyback? - Page 1
Forum section: electronics / projects

author: AcHmed99
author_rank: Contributor
timestamp: February 29, 2012, 04:44:45 pm
content: I’

author: Neilm
author_rank: Super Contributor
timestamp: February 29, 2012, 08:56:31 pm
content: Have you tried measuring the current through the winding, either with a current probe or voltage across a small resistor? I have modeled this in LTSpice and I seem to get similar voltage waveforms passing a current of about 3.6A (probably due to various assumptions made in the simulation).Have you checked the resistance of the secondaries? One mistake it is easy to make is assume that you know how long the turns are and be unpleasantly surprised when they are longer than you assumed they would be.Neil
Multiple ADCs with differential amplifier  - Page 1
Forum section: electronics / projects

author: Cloud
author_rank: Regular Contributor
timestamp: November 24, 2015, 08:35:25 pm
content: I am working on a project, where we are restoring an old pinball machine. Because it will later used as educational equipment we are trying to stuff as much sensor and control circuits inside as we can. So I had an idea about measuring current through solenoids and than have ADC with microcontroller which will in case of overcurrent inform main processor. But because there are 18 (I think) solenoids I am seeking for a solution with multiple ADCs in same housing and preferably with differential amplifier since the shunt resistor will be max 10mOhm.

author: pmbrunelle
author_rank: Regular Contributor
timestamp: November 25, 2015, 04:03:33 am
content: Usually in a microcontroller you have lots of analog input pins, but not many ADCs, perhaps just one. So the analog inputs are multiplexed to just one ADC.Actually, maybe you want to have only one good quality differential amplifier. Then, you switch its input, so that it reads the different shunts (one shunt per solenoid) in sequence. This has the advantage of not needing to trim 18 amplifiers to work identically; because you're using the same amplifier for all channels, the results can be directly compared with each other more easily.
Multiple ARM CPU-s in a single SBC - Page 1
Forum section: electronics / projects

author: sidereal
author_rank: Contributor
timestamp: January 01, 2022, 05:08:03 pm
content: I am looking at multi-socketed motherboards.I notice :I could not find any example of SBCs which has multiple cpusI could not find any examples where multiple ARM cpus exist on a motherboard beyond research projectsIs this an artifact of market forces?? That there had not been any market demand for such a device with multiple arm CPUs on a single board?Speaking of which,1. Who would such an hypothetical system connect their processors ?1. a Will they connect over a single and same north bridge?1. b Can you run NUMA- enabled linux on such a system?1. c Does ARM even support such a thing?2. If I am to take, say, two raspberry pi with ARM cortex on them - and wish to run them in parallel with full memory and cache sharing ( = not via ethernet or firewire) , and assuming I have magical soldering skills - what chipset do I need to combine their memories on board, so that I can2.a avoid bottle necking2.b one ARM Cortex processor (incl. all the cores) can access the memory of the other (slave) board as the master ( = by forcing the slave boards demand to access its own RAM to wait) and vise versa2.c is this even possible without modifications on the existing memory controller of each boards?2.d if the memory controllers were to be changed, so that they can accommodate such a bridge that can support the requests coming from another board to access the resources on another board - are there such memory controllers that can do it ? Are their protocols (even experimental ones) that enable such a thing without forcing pixy dust out of the plastic enclosers involved??I realize that I am walking in very hypothetical lands - but I hope to get some guidance to straighten up my thought process.

author: DavidAlfa
author_rank: Super Contributor
timestamp: January 01, 2022, 06:21:33 pm
content: Why when there're 4 and 8-core sbcs?

author: sidereal
author_rank: Contributor
timestamp: January 02, 2022, 11:02:30 am
content: Fine grained control ? Dedicate one CPU nd all the cores to a particular task, while seprated from the other CPUs and their possible failuresAlso more RAM access?

author: tggzzz
author_rank: Super Contributor
timestamp: January 02, 2022, 11:09:40 am
content: Quote from: sidereal on January 02, 2022, 11:02:30 amGo one stage further and look at XMOS xCORE processors running xC. Theystartfrom the principle that therewillbe multiple interacting cores, and have developed the only hardware+software ecosystem that allows guaranteed-by-designtiming. The IDE states how long each code sectionwilltake - none of this "measure and hope you have captured the worst case" rubbish!Available from DigiKey with up to 32 cores per chip (expandable), 4000MIPS/chip.
Multiple board to board connectors - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: March 07, 2022, 01:22:20 pm
content: I have used in a design 2 double row 2mm pitch TH headers to connect 2 PCB's together. Well I know that it did not help that the recommended footprint was way too big on the hole footprints. But are there any tips or tricks to using more than one connector?I assume that making the holes as tight as I dare so that I do not have alignment issues with the two (or more) connectors is a start.

author: PeteH
author_rank: Unknown
timestamp: March 07, 2022, 01:41:10 pm
content: Samtec has a couple posts on this:https://blog.samtec.com/post/multiple-connector-alignment-on-mating-pcbs/https://blog.samtec.com/post/challenges-of-aligning-multiple-connector-sets/I've seen 1~2 pins being used on PTH connectors as "alignment" drivers, where most of the footprint can have IPC compliant standards holes/pads, but 1-2 of the end pins (on either end) would be tightened up to ensure the connector is straight as possible / aligned, can even offset those 2 holes to pull the connector so that the pins are snug against the barrels on one side.Can also fixture the PTH soldering process for small batches.Large distances between the two connectors scales any skew/amplifies small angles.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 07, 2022, 01:42:13 pm
content: Sparkfun published a suggestion to stagger holes in each row. That helps alignment without making the holes unusually small.

author: eugene
author_rank: Frequent Contributor
timestamp: March 07, 2022, 01:51:00 pm
content: Fixture everything during assembly. For one-offs and prototypes, that usually means putting everything together before soldering.

author: Simon
author_rank: Unknown
timestamp: March 07, 2022, 08:29:57 pm
content: I like the idea of offsetting some or all of the holes. that sounds like a plan. Anyone else using wurth connectors, beware, the hole sizes given in the datasheet are more than generous, more like ridicolous.
Multiple Buck controller, single panel - Page 1
Forum section: electronics / projects

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: August 21, 2017, 05:18:52 pm
content: Hi everyone,Kind of stupid question i think, but as the title said, am planning to use a single panel to power-up multiple smps (as current source) for LEDs.I can't think about anything that make paralleling multiple buck controller possible using a single solar panel,as long as there is enough power.am i wrong ? will all the switching introduce unexpected behavior ?Thanks.
Multiple cams on single board computer - Page 1
Forum section: electronics / projects

author: IG
author_rank: Newbie
timestamp: March 23, 2014, 01:39:26 pm
content: Hello,I want to build portable stereoscopic computer vision module. For that I want to use popular CMOS cam modules like OV5640 / OV9715 (capable of delivering 1280x720@30fps) and a single board computer (like Raspberry-Pi) performing OpenCV computations to extract depth information of a scene. Fastest single board computers that I found are ODRONE (www.hardkernel.com), they produce affordable 4 and even 8 cores systems. After a lot of www research I found that first problem is to get data from CAM modules ... 1280x720 color image produces ~2.7 MB / frame and about 66 MB/s stream for 25fps. And people usually use webcams with MJPEG compression and still can't get enough throughput on USB 2.0 ports. And I want to use TWO cameras for stereoscopic vision...Those ODROID computers have 30Pin ( GPIO/IRQ/SPI/ADC) expansion slot . How do you think - is it possible to connect directly (and able to access for programming tasks) those two camera modules directly ?http://www.hardkernel.com/main/products/prdt_info.php?g_code=G138503207322&tab_idx=2Worst case scenario - I can live with 1280x720 colour image and calculate just low-res 640x360 depth map, but also real time (25fps).Thank You!

author: Rasz
author_rank: Super Contributor
timestamp: March 23, 2014, 02:31:16 pm
content: no, people dont have trouble with mjpeg streamsarm boards usually have one dedicated camera port cpi (parallel) or mipi, board you linked has nonesimplest/cheapest option will be PS3 EYE USB webcamshttps://github.com/mkoval/stereo_webcamhttps://github.com/AmmarkoV/RoboVision/issues/13http://hangyinuml.wordpress.com/2012/07/19/stereo-vision-grab-frames-with-opencv-2-x-ps3-eye/for stereovision syncing both cams is the most important issueps:there was a kickstarter for thishttp://duo3d.com/a long time ago

author: IG
author_rank: Newbie
timestamp: March 23, 2014, 05:25:39 pm
content: Thanks for response! Plain camera modules have VSYNC and FSIN pins for syncing, the main issue is data transfer.And thanks for mentioning CSI ports, but I didn't found any ARM boards with two inputs.Duo3D is very expensive low res cameras, without any image processing hardware as I understand ?

author: Rasz
author_rank: Super Contributor
timestamp: March 23, 2014, 07:21:47 pm
content: duo, at the time of kickstarter, was just a custom plastic case for two ps3 eye cameras, all processing on the pc/arm board
Multiple Capacitor Charger - Page 1
Forum section: electronics / projects

author: 4beowulf7
author_rank: Newbie
timestamp: July 31, 2015, 08:02:17 am
content: Hi guys!I've designed a capacitor charger. This one charges up two high-voltage capacitors at the same time. It may help you if you like HV circuits.https://tr.scribd.com/doc/272912946/Capacitor-ChargerGreetings
Multiple communication IC    - Page 1
Forum section: electronics / projects

author: squeezyballs
author_rank: Newbie
timestamp: November 06, 2023, 12:01:41 pm
content: Hello people,I am looking for an IC that can switch between multiple communication protocols on its output,Does anyone know if an IC like that exist and what are they called?Thank you for your indulgenceYours sincerely,Squeezyballs

author: CountChocula
author_rank: Unknown
timestamp: November 06, 2023, 02:18:53 pm
content: Can you give us more information about what you're trying to do? What you describe is a role that I would normally assign to a microcontroller, which is usually capable of communicating using a variety of protocols (I²C, SPI, UART, USB, etc. etc.). Without understanding your specific use case, it's hard to give any kind of advice.
Multiple connector shield-to-ground bonding in metal chassis - Page 1
Forum section: electronics / projects

author: msedlak
author_rank: Newbie
timestamp: September 12, 2025, 09:30:53 am
content: Question:I’m designing a board that sits inside a metal enclosure (chassis), and I’m not sure what the best practice is for tying connector shields/chassis to the PCB signal ground:• RJ45 (Ethernet): shield is connected to signal GND through 1 nF / 2 kV capacitor (standard practice).• SMA connector: the shell is soldered directly to the PCB ground plane (needed for RF performance) and, since it is panel-mounted, it also bonds directly to the metal chassis.• USB-C (used only as USB 2.0 ): shield is connected to the chassis, and currently chassis ↔ signal ground is tied with 1 nF ∥ 470 kΩ.So the situation is:• RJ45 shield → 1 nF → signal GND• SMA shield → directly to signal GND (and chassis)• USB-C shield → signal GND via 1 nF ∥ 470 kΩMy question: What is the correct/common way to unify these inside a metal chassis?• Should all connector shells bond first to a common “chassis/shield copper” tied once to signal GND via RC?• Or is it acceptable to have some shells directly bonded to signal GND (like the SMA) while others are capacitively coupled?• How do I avoid ESD currents from one connector shell finding a lower-inductance path into signal GND through another connector?Please note also the position of the connectors: the RJ45 is located on the opposite side of the PCB from the SMA, while the USB-C is near the RJ45 on the back panel.Thanks in advance for any tips and answers!

author: tooki
author_rank: Super Contributor
timestamp: September 12, 2025, 10:57:45 am
content: With respect to USB-C, this has been discussed a few times, and the consensus is that the USB-C standard unambiguously states that the connector shell is to be connected directly to the PCB ground plane:https://www.eevblog.com/forum/projects/why-usb-c-gnd-is-being-connected-to-the-shield-of-the-cable-after-connecting/https://www.eevblog.com/forum/beginners/on-devices-side-should-i-connect-usb-cable-shielding-to-the-black-wire/Here’s the USB-C standard:https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf
mcu - Page 1
Forum section: electronics / projects

author: csheldon
author_rank: Contributor
timestamp: May 02, 2018, 02:03:12 pm
content: Hello,

author: bson
author_rank: Unknown
timestamp: May 02, 2018, 11:57:19 pm
content: Hola!

author: BillB
author_rank: Unknown
timestamp: May 03, 2018, 12:38:14 am
content: I love youWon't you tell me your name?
Multiple LED oscillations / pulsations using (tenuous) "Cat's Wisker" switches - Page 1
Forum section: electronics / projects

author: RJSV
author_rank: Super Contributor
timestamp: November 06, 2018, 07:24:09 pm
content: Post#2, please see also Nov. 5 1:58pm post. In detail, an experimental rig passes a +3V DC supply battery through a shared 1K ohm resistor to four connected LEDs. For switching, each Led is connected to ground (minus), by use of a wire strand "Cat's Whisker". A stranded ground wire is mounted nearby, with desired effect of having 'flakey', random contacts to light up each of the LEDs, by way of movement, and possibly also by contact degradation (copper surface oxidizing due to current flow). One visual effect is a so-called 'glory stealing' of a blue LED illumination, when a RED LED is then put into the parallel mix.Now, a RED LED at 1.8 Volts will suppress an illuminated BLUE LED (at 2.5 volts), by keeping the voltage down. (Remember they interact, as they share the 1 Kohm supply resistor). This causes a complementary "one or the other" visual effect where the light appears to move or 'flicker' back and forth, as the RED LED contact acts to switch the lower voltage RED LED in and out of the parallel circuit. That effect is clearly due to the higher illuminating 'ON' voltage requirement of the BLUE LED.Extending this effect to using a 'flakey' switching contact, via the tiny Cat's Whiskers, the visual effect becomes analog, that is the on and off 'flickers' become subtle 'pulsations'. The 'BAD' contacts appear to introduce about 1 K ohms in some cases. This all makes sense... However, there are other similar visual effects, when the experimental rig is using only RED LEDs!With an experiment using just two RED LEDs, each with a Cat's Whisker to minus supply, there is observed similar visual 'surges' between them. For example, LED #1 will be pulsating bright and random for perhaps 30 seconds, and meanwhile LED #2 will be dimly pulsating in opposition (one LED getting brighter while the other diminishes). Also sometimes the 'dominant' LED will come on full for several seconds or more, leaving the other LED dark. Then, often after perhaps 40 seconds, the whole situation reverses and LED #2 takes on the dominant role. I have a tentative, incomplete explanation: With surface contact 'burning' or copper oxidizing the dominant LED eventually cannot sustain illumination. Or, maybe the LED simply is heating up slightly. At any case the dominant LED will stop conducting, allowing the other LED to then take on the role (of flickering / surging in brightness).I am stymied by the behavior of this, as the mechanical contacts would have to coordinate for this 'one or the other' trading of the LED dominance. That's a stretch to believe. Wondering also, perhaps there are so-called "NEGATIVE RESISTANCE" effects on the diode V/I curves,as seen in the micro-wave PIN diodes used in radio transmission. Any help or even whacky theories out there? Sorry no schematic. Thanks
Multiple LED's,  5V source, EMC compliance - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: May 10, 2020, 11:22:10 pm
content: I need to design a simple white LED circuit with 9 LED's in an array all on at the same time, not sure on total power but somewhere between 2-5W total.Walwart 5Vdc power supply, perhaps something like this:https://www.digikey.ca/en/products/detail/cui-inc/SWI5-5-N-MUB/6579911The circuit will need to pass EMC compliance test first time, so I prefer to avoid switch mode current regulators.I'm considering using a voltage regulator configured as a current regulator, and simply parallel all the LED's and hope that the variation in brightness LED to LED is not overly noticeable.Has anyone tried this?

author: mawyatt
author_rank: Super Contributor
timestamp: May 11, 2020, 12:25:28 am
content: From what you've indicated these 9 LEDs will draw about 1 amp total, so each LED will require ~111ma. From my limited experience with LEDs (more on the higher power area than lower power) you can't depend on them current sharing when paralleled. You can use separate ballast resistors for each LED, or better yet design a current source with 9 equal outputs. For this current source I would use PNP rather than PMOS output devices, since discrete bipolar transistors match better, and use a modest emitter degeneration, maybe 3~5 ohms.Best,

author: dragondude
author_rank: Newbie
timestamp: May 11, 2020, 12:42:06 am
content: You could use a DS2003 darlington driver or 2 with load resistors to limit the current to about 30 to 60 mA per LED. You need the specs for the LEDS before jumping in. What you are trying to do has been done 000,s of times before so simple circuits will be on the web somewhere. Also I am not sure of the quality of Walmart products but if you want EMC compliance I would buy a quality power supply.
multiple li ion battery packs on 1 line - Page 1
Forum section: electronics / projects

author: jdolecki
author_rank: Contributor
timestamp: February 26, 2021, 02:27:19 pm
content: If I have multiple Li ion battery packs ( thick RC batteries) on the same line will the higher charged packs dischargeinto the lower charged packs?Can I put diodes on the + line to prevent the backflow of current into the lower charged packs.I hope I explained the correctly I'm new at this.thanks john

author: tunk
author_rank: Super Contributor
timestamp: February 26, 2021, 02:53:12 pm
content: If you by "on the same line" mean in parallel, then yes.Have no experience with RC batteries, but I think (?)they're high current, so you would need high currentdiodes. Why do you want to do this?

author: jdolecki
author_rank: Contributor
timestamp: February 26, 2021, 03:08:37 pm
content: my idea

author: strawberry
author_rank: Super Contributor
timestamp: February 26, 2021, 06:39:37 pm
content: there is chance to overload stronger pack in circuitprismatic cells are not as durable as 18650
Multiple MBI5034 for 16x32 RGB LED matrix display - Page 1
Forum section: electronics / projects

author: sangar
author_rank: Regular Contributor
timestamp: December 01, 2018, 07:48:31 am
content: Hi All,I have one LED controller board which has 16 x 32 matrix LEDs and 12 MBI5034 LED drivers in the top and bottom, totally 24. I am trying to figure out that each MBI5034 drives how many LED strings (it could be 16 as it has 16 output current ports) and how many LEDs each string has...Right now, the board is not in my hand to take a photo and post it...Please suggest...Regards,Muthu
Multiple MOSFETs in a single package? - Page 1
Forum section: electronics / projects

author: MacAttak
author_rank: Unknown
timestamp: June 14, 2013, 02:03:58 am
content: I was looking at this application note about bi-directional level shifting:http://ics.nxp.com/support/documents/interface/pdf/an97055.pdfThe design calls for discrete MOSFETs (N enh) plus some passive resistors. For a simple shifting implementation, it requires two transistors per signal line. In this case, I would like to perform automatic level shifting for a lot of signals - roughly 80 to 90. Going with discrete transistor packages, there is no way I could hope to fit that many (plus three resistors for each signal) on a PCB of reasonable size. And while buying a few chips won't break the bank, when you need ~200 for a single board it adds up. Example transistor mentioned in the app note:http://www.digikey.com/product-detail/en/BSN20,215/568-1658-1-ND/763485I've tried looking for multi-FET array packages for this application, but haven't turned up anything. Surely someone must offer quad FETs in a single chip (or 16, or even 8 )?I know that normally, you would only perform level-shifting on the few signals you care about, but in this case I want to have a general-purpose level shifting adapter that lets me plug average 5v Arduino-style shields into my FPGA board that only wants 3v3 (and I don't think it is 5v tolerant, nor would I expect the 5v shields to be 3v3 tolerant).All of the purpose-made level-shifting chips I have seen that can handle multiple signals are useless for this purpose, because they are either unidirectional or they require another external signal to control the direction of all shifted lines.

author: Unknown
author_rank: Unknown
timestamp: June 14, 2013, 02:59:16 am
content: I have some dual mosfets in a SOP-8 package. Pretty compact. CEM4953 (I believe). I bought 50 for around $16.

author: c4757p
author_rank: Super Contributor
timestamp: June 14, 2013, 03:01:01 am
content: Two MOSFETs per SOIC-8 ishugeif you want to level shift 90 signals with them!

author: Unknown
author_rank: Unknown
timestamp: June 14, 2013, 03:01:30 am
content: It was SOP-8. My mistake. They're pretty little guys.

author: croberts
author_rank: Regular Contributor
timestamp: June 14, 2013, 03:06:25 am
content: DigiKey does have MOSFET arrays in Product Index --> Discrete --> FETs - Arrays but only 4 per package max as matched pairs.

author: free_electron
author_rank: Super Contributor
timestamp: June 14, 2013, 03:19:11 am
content: there are chips that have that circuit avaialble in ulti lanes ( up to 8 i believe ) maxim and linear technologies have em. max 37xx series i believe. made for i2c and spi busesst has one in flipchip ( really tiny )

author: Rufus
author_rank: Super Contributor
timestamp: June 14, 2013, 03:33:50 am
content: Analog do some octal bus switch/passive level translators. ADG3300 is a 5v capable example.