hybridfree/eevblog-posts huggingface dataset:
+2 million Volts from a small self defense stun gun, plausible/needed? - Page 1
Forum section: electronics / projects

author: mcinque
author_rank: Unknown
timestamp: September 23, 2017, 04:59:15 pm
content: They claim 2.400.000 Volts (of course infintely small current, it's not specified how much).Is this kind of voltage plausible/needed for a stun gun or is just for marketing? Do they haveenough space/isolationto reach that voltage in a handheld product avoiding arcing and shock to the owner?I've read tasers discharge 25 Watts of power at 50.000 Volts (and they're really effective!).

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 23, 2017, 05:57:19 pm
content: There is another whole thread on this class of devices. The advertising claims just keep climbing. The only limit I see is the number of digits they can fit on the page with multipliers that the advertisers know.https://www.eevblog.com/forum/chat/new-physics/msg1159399/#msg1159399

author: Cerebus
author_rank: Super Contributor
timestamp: September 24, 2017, 02:42:11 am
content: Ponder this: The approximate dielectric breakdown voltage of air is 3,000,000 volts per metre, for PTFE it is 19.7 MV/m, polythene is similar, so is PVC. That covers most of the common insulators you're likely to find in some electronics. Given that information you don't even need to do mental guesstimation to realize that something hand held isn't going to have enough room to isolate two conductors with a 2.4MV potential difference between them, even if it was made from solid plastic with no air gaps.Edited to add: And don't even talk about creepage distances at 2.4MV - remember, you have to hold this thing to use it.

author: David Hess
author_rank: Super Contributor
timestamp: September 24, 2017, 03:48:57 am
content: Quote from: blueskull on September 24, 2017, 02:53:20 amExactly, the voltage never gets higher because something, hopefully the air, breaks down first. When using it on a person, the voltage is even lower and it operates more like a constant current or constant power source.
2-module DIY data logger with mini breadboards that swaps sensor modules easily - Page 1
Forum section: electronics / projects

author: TriplePointDesign
author_rank: Newbie
timestamp: December 06, 2023, 08:21:48 pm
content: The educational side of the project required different sensors for each lab, so we tweaked last years 2-part logger with 3D printed rails holding mini breadboards to provide this flexibility. The software has also been streamlined significantly and people shouldn't have too much trouble adding other sensors provided you stick to 1,2,4,8 or16 bytes/record and your modules don't pull more power than the coin cell can provide. The small form factor makes these easier to deploy, and the centrifuge tube is waterproof to several meters depth.https://thecavepearlproject.org/2023/12/01/the-e360-a-classroom-data-logger-for-science/
2 Port USB Connector as SMD - Page 1
Forum section: electronics / projects

author: ChristopherN
author_rank: Unknown
timestamp: March 09, 2019, 08:23:09 am
content: Hi,I'm looking for a two port USB connector like this as surface mount:https://www.digikey.de/product-detail/de/samtec-inc/USBR-A-D-F-O-TH/SAM10376-ND/6679113I have a project where place is a premium so I would like to mount an display on the opposite side of the board which is impossible with a thru hole connector. The connector will be mechanically supported by the housing and see very few plug events over it's lifetime (maybe about 10).Does anyone know where I could source such a part as surface mount part?ThanksChristopher

author: jayeye
author_rank: Contributor
timestamp: March 23, 2019, 03:34:28 am
content: I've never seen SMT stacked usb connectors. I'm pretty sure they are a terrible idea. If space is at a premium, how about using micro-USB connectors?Of course, with enough will, everything is a surface-mount component... just bend the pins

author: tooki
author_rank: Super Contributor
timestamp: March 31, 2019, 09:30:07 am
content: Quote from: jayeye on March 23, 2019, 03:34:28 amWell, this is the USB type A connector. While a micro-A does exist, it’s exceedingly rare.If I needed a compact computer-side USB connector, I’d use USB-C.

author: JagV12
author_rank: Contributor
timestamp: March 31, 2019, 11:03:06 am
content: You can tilt the connector 90 or 180 degrees and use a daughter board. If no mechanical stress, you can even solder the daughter board directly perpendicular to the main board as any SMD. To help with stress, you can also glue the connector.

author: mariush
author_rank: Super Contributor
timestamp: March 31, 2019, 11:25:30 am
content: You could use connectors like this one, and have a tiny PCB on the back:https://www.digikey.com/product-detail/en/molex/0484090003/WM10422-ND/4701518Or two of these and have the tiny pcb on the side, which would allow you maybe to use a right angle connector on the tiny pcb to connect to the main pcb:https://www.digikey.com/product-detail/en/stewart-connector/SS-52000-002/380-1410-ND/7902375Maybe use a flex strip or surface mount connector to connect the usb pcb to the main pcb, to reduce risk of solder cracking due to multiple insertions, mechanical stress etc..

author: ChristopherN
author_rank: Unknown
timestamp: March 31, 2019, 11:48:07 am
content: Thanks for all the good suggestionsI'll try cutting the leads flush with the PCB for now and hope that that will create no follow up problems. If that doesn't work I'll get the daughter board designed in.
2-quadrant MDAC attenuator low output voltage AC operation - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: August 08, 2014, 10:53:44 pm
content: So if I want to attenuate a small signal using a 2 quadrant MDAC with an offset voltage. However, when I am really attenuating the crap out of it, that offset voltage is going to get attenuated too.So I can put a DC bias (~7V) on the input AC signal (milivolts) to have an output of 100uV DC offset (16 bit attenuation). @ full scale attenuation with aTINYac signal that will be AC coupled to whatever (as I must get rid of the amplifier offset anyway). (the attenuated signal will probably be beneath the noise floor of the MDAC but this is ok! so long it is there) (tiny increments!)Are there any problems that I should be aware of for this? Should I use a bipolar configured AC coupled MDAC for any reason? Do MDACs for any reason not like working with signals that are very near ground?the bandwidth looks fine.the dac is being used as a set and forget kind of deal. I am not going to be "modulating" anything.the op amp connected to it would have dual supplies though. I am just trying to be cheap with the DAC (dual supply MDACS have a larger package and are pricier, i'd rather avoid the external resistors etc required to turn a 2 quad into a 4 quad)*ultra sonic frequency AC sig attenuation is of concern hereand I don't really have a set model # for the DAC in mind. None of the data sheets I read seem to describe any concerns like this on AC attenuation.

author: SArepairman
author_rank: Frequent Contributor
timestamp: August 09, 2014, 07:18:24 pm
content: bump. I don't really have a way to test this thing without building the entire, rather pricy, circuit, and I would hate to run into a problem here and have to dead bug some 16 bit SMD MDACunless some kind soul wants to give me some money for a nice lock in amp(though at this point I don't care ill have a BGA "spider monster" assembled by the local warhammer club if it would help a damn)does anyone have any feedback?
2 Way DC motor School Project - Page 1
Forum section: electronics / projects

author: dauntlessaussie
author_rank: Newbie
timestamp: April 18, 2015, 12:37:00 pm
content: I emailed Dave who recommended putting it on the forum, I am just wondering wether or not this circuit will work or not. It is meant to drive the motor in two directions (not at the same time of course).The Dauntless Aussiewww.youtube.com/user/TheDauntlessAussie

author: Phoenix
author_rank: Frequent Contributor
timestamp: April 18, 2015, 12:54:52 pm
content: Can you explain how you expect the circuit to work? Also you should look up how to draw an normally open and normally closed switch.(This should probably be in beginner).

author: LukeW
author_rank: Frequent Contributor
timestamp: April 18, 2015, 02:42:19 pm
content: The classic way to do this is to use a single DPDT switch which crosses over the polarity of the DC power going into the motor.It should look like this, basically:http://commons.wikimedia.org/wiki/File:Crossover-switch-symbol.pnghttp://www.homebuiltrovs.com/howtos/controloptions/forwardreverseswitch.jpg

author: dauntlessaussie
author_rank: Newbie
timestamp: April 19, 2015, 10:01:45 am
content: This is the switch I haveThe Dauntless Aussiewww.youtube.com/user/TheDauntlessAussie

author: Psi
author_rank: Super Contributor
timestamp: April 19, 2015, 10:11:27 am
content: The motor goes across the two switch commons.One end of the switch has negative and positiveThe other end of the switch also has negative and positive but in the opposite position.So the switch connects the 2 motor wires to the battery around one way, or around the other way.Exactly how LukeW has posted in his 2nd URL.

author: Ian.M
author_rank: Super Contributor
timestamp: April 19, 2015, 10:42:07 am
content: Get rid of the 2K2 resistors. They'd only allow slightly over 2mA to flow which wouldn't be enough to turn any motor you are likely to encounter.+1 for using the reversing switch schematic from LukeW's second link.
2 zener diode in series  - Page 1
Forum section: electronics / projects

author: hussamaldean
author_rank: Unknown
timestamp: February 05, 2020, 07:57:15 am
content: Hi all,since I am looking for a 16V zener diode and it is not available here in Iraq, but what I have is 7.5V (something near that value). is it possible to connect 2 of them in series to get high voltage ?I want to stable the gate voltage of a mosfet and it won't reach beyond 16Vregards

author: moffy
author_rank: Super Contributor
timestamp: February 05, 2020, 08:08:01 am
content: Yes, 2 x 7.5V zeners in series = 1 x 15V zener.

author: hussamaldean
author_rank: Unknown
timestamp: February 05, 2020, 08:08:53 am
content: Quote from: moffy on February 05, 2020, 08:08:01 amthx
200A BMS PCB stackup - Page 1
Forum section: electronics / projects

author: pmendiuk
author_rank: Contributor
timestamp: September 22, 2022, 02:28:37 pm
content: Hey All,I have been looking at various high current (200A) BMS and most of the manufacturers have little or no documentation or detailed specifications available on line. I'm starting to consider designing my own and I've looked at some source down MOSFETs (Infineon IAUT300N10S5N015ATMA1 300A 0.15mOhm) and wondered about what kind of PCB stack ups are being used for these MOSFETs. Some of BMS PCBs I've seen have bus bars sweated down on some of power paths but not all high current power paths have bus bars. I assume the power paths are multilayer but the via stitching on those boards is not very dense.

author: strawberry
author_rank: Super Contributor
timestamp: September 22, 2022, 03:21:13 pm
content: most BMS protect only against cell undervoltage and/or overvoltagewith poor over current circuitsmost of them use 1Mohm resistors to turn MOSFET on (low power consumption but MOSFET turns on slow/linear ) reason why they are so many in parallelsome use programmable fuel gauge or what not. need expensive programmer to set custom cell voltage and stuff200A is serious design 14kW@70Vwelding cables...uneven current distribution over MOSFET...

author: pmendiuk
author_rank: Contributor
timestamp: September 22, 2022, 04:01:53 pm
content: Yes I agree serious design with those currents. The various Chinese BMS I've looked at on line don't instill a lot of confidence. I'm thinking about a latching contactor as an alternative but I'm still curious about how those MOSFETs are adequately connected to those bus bars through FR4.

author: nctnico
author_rank: Super Contributor
timestamp: September 22, 2022, 04:08:56 pm
content: Wurth has high current PCB-to-busbar solutions but I would typically derate any such solution by 50% for real world use.
20bit PWM class D amplifier idea - Page 1
Forum section: electronics / projects

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: September 26, 2021, 11:27:39 pm
content: To transform 16bit into PWM 200khz, it requires less than 80ps definition not possible these days more than 11 bits from commonly found DSPs. How about splitting the word into two 10bits MSB and LSB and treat them in parallel. With 10MSB, the amp powered by 50volt BTL, only +/- 50mv is necessary to be complimented by the remaining lower bits. A 5 volt powered PWM with a 50:1 ratio transformer adds to the output the remaining lower bits. The addition takes place after low pass filters so that the transformer's mutual inductance and a capacitor provides the same low pass to the additive low bits. Here is a schematic of the idea.What can possibly go wrong? please comment with most pessimistic arguments.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 26, 2021, 11:38:04 pm
content: You still need the 80ps timing on the power DAC.I don't see any arrangement for feedback, I'm assuming this is all open loop right? Far easier to do it with a modest-order D-S DAC, with a precision comparator to sense the error and drive it towards zero. You get full ENOB at DC up to some frequency, then noise takes over (ripple + quantization). Using a higher order D-S or "noise shaping" helps push the spectral content up towards Fs, yielding higher BW at ENOB for the same Fs.Tim

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 27, 2021, 01:49:44 am
content: Quote from: T3sl4co1l on September 26, 2021, 11:38:04 pmYes. That's how it's done these days. Modern audio class-D amplifiers do not implement simple PWM. They use delta-sigma (or sigma-delta, I tend to use the latter term while it's the same thing) modulators.

author: Berni
author_rank: Super Contributor
timestamp: September 27, 2021, 05:17:14 am
content: The potential issue here is matching the two precisely enough. When you are working with 10bit that last bit is worth 0,1%. So the ration between the two amplifiers has to be within that, otherwise the smallest bits end up turned into just extra noise.The actual solution is better methods of modulation. There is no strict rule to use PWM, anything that switches well out of the audio range will work. A single pulse does not need the full output bit depth since what counts is the sum of everything within the sample time. Things like sigma delta use this to distribute the error out by keeping track of the error and driving it towards 0. Most of the modern audio DACs you end up listening to are actually just 1 to 5 bits running at 1 to 50 MSPS, it's the sigma delta modulation placed in front of them that makes them capable of playing 24bit audio with noise figures in excess of -100dB
20W speaker amplifier - Page 1
Forum section: electronics / projects

author: Simon123
author_rank: Regular Contributor
timestamp: April 22, 2014, 06:18:56 pm
content: Hello!I kinda designed 20W speaker amp and would like, that somewhone would check it and point out the errors.Base current of TR1=350uA, Ic=35mAIB TR2= 35mA, Ic=1,78A2n3055 collector resistor is to low value for power, il change that.I realy dont care about current consumption, cuz i have 10A transformer and that shouldnt be big deal.Is 2N3055 good for audio?Is this designed properly for class A amplifier or AB, dont care ?Thanks!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 23, 2014, 12:16:55 am
content: The first stage looks right, the second stage is suicide biased. You cannot rely on hFE, it is a secondary parameter and varies by about 250% between different pieces of the same transistor type, different brands, and over temperature and operating current.There are better ways to heat ones' home,Tim

author: Simon123
author_rank: Regular Contributor
timestamp: April 23, 2014, 06:13:33 am
content: Should i make it voltage divider then?

author: peter.mitchell
author_rank: Super Contributor
timestamp: April 23, 2014, 08:49:54 am
content: Is this project for learning or just to make a practical quick widget? if it's to make a quick practical widget, for the price of 3x 2n3055s you can buy aTDA7292and you're almost done.

author: wiss
author_rank: Frequent Contributor
timestamp: April 23, 2014, 08:56:13 am
content: Quote from: Simon123 on April 23, 2014, 06:13:33 amIf you insist on going discrete, yes!And an emitter-resistor on the power-transistor to somewhat control the gain and bias-current.This will be a very good way to heat your home and spend money on heatsinks.

author: Simon123
author_rank: Regular Contributor
timestamp: April 23, 2014, 12:34:28 pm
content: Its kinda for learning, so i can understand all on the circuit.To understand some pushpull ic is more dificult if i dont understand this.As heatsink il proably just use 3mm piece of aluminium.Thanks for replying.

author: madires
author_rank: Super Contributor
timestamp: April 23, 2014, 12:58:12 pm
content: Quote from: Simon123 on April 22, 2014, 06:18:56 pmOne or two secondary taps? If it got two go for the classic push-pull approach. BTW, to calculate a proper input coupling cap please use f = 1 / (2 * pi * R * C). That's the lower frequency limit at -3dB (coupling cap plus input impedance creates a RC filter).

author: wiss
author_rank: Frequent Contributor
timestamp: April 23, 2014, 02:00:04 pm
content: Quote from: Simon123 on April 23, 2014, 12:34:28 pmSure, go for lower power and it will workQuotea few sqaremeters?

author: Simon123
author_rank: Regular Contributor
timestamp: April 23, 2014, 04:16:37 pm
content: OK, il calculate capacitors, this is just some aproximation i think should work.I only have single sec. tap.Il use fan for transformer in powerhouse also.
21-Pole LP Chebychev Filter Project - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: December 23, 2012, 04:25:49 pm
content: Hi all.This is about the 4th or 5th passive filter I've designed and built up to now. I have been attempting many different methods of building filters, from in-line coils with capacitors tapped to ground at strategic points, to the standard PCB style. Most failed miserably due to parasitic elements I didn't take into consideration, but this one seems to perform a lot better.It is a 21-pole low-pass Chebychev design, with all inductors and capacitors the exact same value except for the input and output ones, which are slightly lower value. Its designed for use in the FM band (76MHz to 108MHz) so I designed the cutoff frequency a little higher (125MHz.) Funnily enough, the parasitics on the board did not reduce the -3dB frequency by any amount. It measures exactly 125MHz!I was going to stitch both ground planes (top and bottom) together through all the holes, but got bored and only stitched enough so the performance is good up to about 500MHz. Some of those pesky microwave frequencies can obviously sneak inbetween the gaps, but my radio transmitter doesn't produce any horrible harmonics in the 1GHz+ range, so no problems there.Enjoy the pics.EDIT: P.S. Any advice on proper via stitching would be greatly appreciated!

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: December 23, 2012, 06:03:16 pm
content: Good stuff! What is the IL value?I have been scratching my head while building 150MHz BP filter in a similar fashion and I can't figure out what would be the best way of positioning the nearby coils. Placing them the way you did does not minimise cross-coupling. Is there science behind it?I am surprised attenuation is around 70dB without shielding and compartmentalisation.Why did you put capacitors alternating between the top and bottom GND strips? If you visualise the current flowing through each LCC tank then you will see that it has to go through two caps on the opposite sides of the strip, through the GND stitching and the bottom GND plane. If caps are grounded to one side it would make current flow shorter. I wonder if it would make much difference at VHF frequencies . But at 1GHz+ it might.Leo
2114 RAM versus 6264 SRAM  - Page 1
Forum section: electronics / projects

author: DMartens
author_rank: Contributor
timestamp: April 12, 2024, 01:35:43 pm
content: Hi ... I'm into late 70's and early/mid 80's retro-style computers and designs based on CPUs such as the 6502, Z80, 6800, 8086 etc ... and many of the design of the time used RAM memory chips such as the 2112, 2114, 6664 and similar ... can the RAM chips in these designs typically be implemented using more modern SRAM chips such as 6264, 62256 or equivalent ... obviously the modern ones can store more data and the data/address lines would need to be properly connected ... but I was wondering if there are other factors to consider such as access speed, mode of operation, etc.

author: jwet
author_rank: Frequent Contributor
timestamp: April 12, 2024, 03:11:28 pm
content: Yes, almost universally, but watch logic level compatibilities. Old 21xx SRAM's were NMOS and had TTL like thresholds (.8/2.0). The later 62xx series are CMOS and produce output rail to rail signals (no problem) and the inputs are generally TTL compatible too (like HCT CMOS). Most vintage processors of the time were NMOS so shouldn't be an issue. Double check data sheets. Other mostly positive gains: The 62xx series are faster and lower power, standby currents on 62xx devices can be miniscule, good for battery backed RAM if that appeals to you.

author: Gyro
author_rank: Super Contributor
timestamp: April 12, 2024, 08:48:28 pm
content: You could use a couple of 62256s (64K bytes total) and deselect it when anything else in the memory map is enabled. That would get you maximum RAM space. Either that, or if the memory map allows (everything except RAM in a 32k space), just use single 62256, chip selected by A15 or /A15.

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 12, 2024, 09:36:11 pm
content: No problem in general, as long as it's static RAM, more modern ICs will usually have shorter access times, which is all good. The one thing though is that if you need 5V stuff, you'll be limited to ICs that are, while more recent than the ones you mentioned, still now considered "vintage" and not necessarily very easy to source (except on eBay or the like).I've bought a few 512KByte / 5V SRAM chips a few years ago for some project. Got them off eBay IIRC.
22-410 meter from Radio Shack. RIP. Decent substitute? - Page 1
Forum section: electronics / projects

author: mmb
author_rank: Newbie
timestamp: November 15, 2015, 01:58:15 am
content: The senior guy at my local R-S says the 22-410 nominal 15 V F.S. meter was discontinued in 2011. Sigh.I've looked at what Velleman offers and am dissatisfied. I also hate the cheesy meters sold at car parts stores. I have popped the lid of the one remaining 22-410 I own and customized it with some color-dot callouts, but in the process I let a little slip of the Datak film slip down in there, and I can see it but not retrieve it. Yes, I've tried the Scotch tape trick. Roops, I'm a bad person.Seems to work OK but I know that some day it'll mess up on me.d'Arsonval movements are out of fashion, I know, but I really like the fact that this sucker only draws 1 mA full scale, is "always on", and reads the voltage fluctuations in my car's electrical system without requiring the cognitive load a DVM does.Anyone know a good source for this sort of thing? I could wish for illumination and possibly white-needle-on-black-face, but the 80-20 payoff is what I've got now and am content with.eBay for this exact meter is a no-go, so far.

author: dadler
author_rank: Unknown
timestamp: November 15, 2015, 02:17:46 am
content: http://www.newark.com/webapp/wcs/stores/servlet/Search?catalogId=15003&langId=-1&storeId=10194&categoryId=800000005089&pageSize=25&showResults=true&pf=810055385,810103951

author: oPossum
author_rank: Super Contributor
timestamp: November 15, 2015, 10:04:37 am
content: There is a 22-402 on ebay...http://www.ebay.com/itm/221924681515
220V AC be interfering with RF signal (MICROCHIP MRF49XA)? - Page 1
Forum section: electronics / projects

author: onesixright
author_rank: Frequent Contributor
timestamp: April 22, 2014, 12:25:09 pm
content: Hi,I got a question from a friend. Its way out of my knowledge, so i hope someone can shed some light ion this. This information is somewhat limited, but maybe enough to understand whats going on.They have a electronic thermostat. It communicates (RF 433 MHz) with a heating system, via a MICROCHIP MRF49XA. Now the signal seems to be unreliable. Looking at the design we see a 220V AC wires being 'routed over' (there is a gap of a few mm) the RF chip.The box is roughly 15cm x 8 cm. The power input is on the left, the power switch is on the opposite side. So the AC wires (2x) go into the switch (crossing the RF chip, and 'hanging' free inside the case), and then back to the PCB. On the PCB the 220 is switched via couple of relays to the heating elements, and there is a voltage regulator that powers the PCB). So, basically the 220V is passing the RF chip twice.My question: could this 220V AC be a cause for interference (and with that unstable RF link)? Shouldn't you need to keep the AC lines as short as possible?Moreover, and now it get really weird. The box has vent holes for cooling. For some reason, when you switch on the box, and wipe your hand over the box (touching the cooling holes), the signal is lost. This can be repeated with same result. My initial thought would due that you create some static electricity somehow. But maybe thats too far fetched? Curious if this 'effect' is something common?Thanks!

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 22, 2014, 12:37:34 pm
content: What is the HISTORY of the problem? Is this a brand-new installation that has NEVER operated properly? For HOW LONG? Was this system operating properly at some time in the past? For how long?It sounds to me more like 433 MHz INTERFERENCE to me than any kind of PROPAGATION problem (unless it has NEVER worked.)

author: wraper
author_rank: Unknown
timestamp: April 22, 2014, 12:50:35 pm
content: Does the communication become unstable when switching relays? My guess is that arching contacts might interfere with the receiver. About touching box, how far devices are located? Aren't they located too far away that you interfering with a hand is enough to distract communication? Is there any shielding? Antenna is external or internal?

author: Niklas
author_rank: Frequent Contributor
timestamp: April 22, 2014, 02:57:27 pm
content: As wraper wrote, the arching in the relays can do all kinds of magic tricks. High frequency transients on the wires can also cause problems, such as flipped memory cells. State machines, like UARTs, I2C etc, can be triggered and become out of sync.
220V HSPY 400-01 Adjustable Power 400V/1A programmable Digital DC Power Supply - Page 1
Forum section: electronics / projects

author: Tronic
author_rank: Newbie
timestamp: June 07, 2022, 08:22:54 am
content: Hi folksI am trying to source a hybrid battery grid charger for a 2009 Toyota Estima Hybrid car and there doesn't appear to be any available so I have been looking at the DC power supply (220V HSPY 400-01 Adjustable Power 400V/1A programmable Digital DC Power Supply). Does anyone has any experience in using such a power supply to recondition a hybrid car battery?Thanks.

author: TheMG
author_rank: Frequent Contributor
timestamp: June 07, 2022, 07:09:25 pm
content: Probably better if you can gain access to individual battery cells to use smaller lower voltage power supplies/chargers for this, or at least split up the pack into more manageable parts (safer too). The more cells you have in series the more chances there will be imbalances, which will be a detriment to attempts to "refresh" the NiMH pack. It could even be damaging if you plan on deep discharging it as part of the refresh process as weaker cells could go negative and that is not good for them.
220VAC - 12VDC SMPS with Power Good signal - Page 1
Forum section: electronics / projects

author: rfdes
author_rank: Regular Contributor
timestamp: January 03, 2018, 05:49:09 pm
content: I would like to find a power supply that has a feature which would supply a signal signal (ex. open drain) should the AC power to the supply be removed. The goal is to retrofit an existing product to detect when the AC power has been removed. The signal would then trigger a controller board such that a friendly shutdown of the controller can be attempted.Input: 220VACOutput: 12Vdc @ 10WSignal Output: Open Drain - Power GoodI am having trouble locating an SMPS vendor that sells power supplies that have a 'power-good' output. Does anyone know of a reputable vendor which sells off the shelf power supplies with this feature?ThanksJim

author: Tomorokoshi
author_rank: Super Contributor
timestamp: January 03, 2018, 06:12:20 pm
content: Something like this:https://www.digikey.com/product-detail/en/mean-well-usa-inc/MDR-10-12/1866-1027-ND/7705057has a DC OK output. However, you would have to test it to see if there is enough warning time. I looked around for something that indicates AC OK and it seems scarce for anything under 50W.

author: rfdes
author_rank: Regular Contributor
timestamp: January 03, 2018, 06:37:34 pm
content: Yes, AC OK would be better. The spec sheet calls out 120mS hold up time, although I'm not sure how the DC OK timing is related to this spec.I appreciate you looking. I'll start there and see where it takes me.Thanks -Jiim

author: _Wim_
author_rank: Super Contributor
timestamp: January 03, 2018, 08:36:46 pm
content: I think it might be easier to opt for 2 devices, 1 "device" to detect AC present, and a regular power supply. To detect AC, you could just use a relay with an AC coil...

author: ahbushnell
author_rank: Frequent Contributor
timestamp: January 03, 2018, 11:51:54 pm
content: Quote from: _Wim_ on January 03, 2018, 08:36:46 pmI was thinking a relay might be good. I guess it depends on at what low AC voltage they want the AC good signal to trip?Andy
22V applied to analog switch connection pins of multiplexor, when not powered - Page 1
Forum section: electronics / projects

author: opampsmoker
author_rank: Regular Contributor
timestamp: November 11, 2020, 09:32:47 pm
content: Hi,Please advise what will happen if 22V is applied to either the S1,S2.....S8 or D pins of the ADG1438 multiplexor when the ADG1438 is not powered?ADG1438 datasheet:https://www.analog.com/media/en/technical-documentation/data-sheets/ADG1438_1439.pdf

author: ejeffrey
author_rank: Super Contributor
timestamp: November 11, 2020, 09:39:42 pm
content: That exceeds the absolute maximum ratings so you have to assume the device will be destroyed.

author: exmadscientist
author_rank: Frequent Contributor
timestamp: November 12, 2020, 05:35:15 am
content: If you really need to do this, Analog Devices has a newish line of fault-protected analog switches, with overvoltage ratings of up to 55V, in either polarity, even when unpowered. One such device isADG5208F; they have others.As one might expect, there are drawbacks. The channel on-resistance is rather poor at around 270Ω (this is probably related to the protection), there are several edge cases on the protection (mostly in unsurprising places, anyone trying to sell you a protection network with no weird edge cases at all is definitely lying), and then there's the literal cost: $4.21 each in volume, factory direct, or over double that from distributors in small volume.But if it helps you get out of a tight spot, it's worth it.

author: Zero999
author_rank: Super Contributor
timestamp: November 12, 2020, 01:58:13 pm
content: Quote from: opampsmoker on November 11, 2020, 09:32:47 pmThe inputs have built-in clamping diodes, which will take up to 30mA, so a current limiting resistor will do. Technically anything over 1k833 will do, but you'll want to use a higher value than that. If the power supply rails have no other load, than the ADG1438, add zener diodes (22V will do), or resistors (value dependant on the current limiting resistors), to prevent the voltage from exceeding the maximum rating.
230V AC inline power supply - Page 1
Forum section: electronics / projects

author: davorin
author_rank: Unknown
timestamp: July 29, 2014, 10:13:23 am
content: Does anyone have a good idea how a small device just using 3.3 - 5V DC can be powered in series with a light bulb for example, which then can be switched on/off by the device itself?Something like an inline powered SSR.When the switch is off, the powering is not a problem as the current would be very low on the primary side....But when the switch is on it needs to have enough voltage drop across so it could still be powered.

author: Berni
author_rank: Super Contributor
timestamp: July 29, 2014, 10:55:21 am
content: Put two back to back Zener diodes in series as well then you can always keep a 5V or whatever voltage Zener you use
230v or 415v AC to 24v PSU - Page 1
Forum section: electronics / projects

author: andybarrett1
author_rank: Regular Contributor
timestamp: November 05, 2015, 04:19:48 pm
content: Hi AllLooking for a means of getting a decent 24v DC supply (low current) from 230 or 415ACHave looked at using X2 cap/resistor/zener option but no isolation from mains which will be needed...Wondering if can still use this method but then into a switch mode so using the switch mode as isolationJust looking for ideas at moment .... Has to be small and cheap !All ideas welcome !Thank you for readingAndy

author: Paul Price
author_rank: Super Contributor
timestamp: November 05, 2015, 06:52:57 pm
content: The really important question here to offer a solution is for you to reveal what current you call low current?

author: andybarrett1
author_rank: Regular Contributor
timestamp: November 05, 2015, 07:01:07 pm
content: No more than 250mA... Maybe less than that.A 4-20mA Loop1 PIC Chip2 PCB Mounted 5v Relays3 LedsAs a start point !TYAndy

author: Paul Price
author_rank: Super Contributor
timestamp: November 05, 2015, 07:08:16 pm
content: You say the 24V power supply must work also using 415 RMS VAC power line input as well?Otherwise, a transformer:ABL6TS02BSCHNEIDER ELECTRICIsolation Transformer, Phaseo Optimum, 25 VA, 1 x 230V, 1 x 400V, 24V secondary

author: station240
author_rank: Unknown
timestamp: November 05, 2015, 07:18:55 pm
content: You can use a Buck/Boost Inverter with a transformer instead of a coil.That would give you the isolation at the output. Feed the inverter from the X2/resistor/zener supply.Another option is to rewire/rewind a CCFL inverter that just has a transistor based driver.

author: andybarrett1
author_rank: Regular Contributor
timestamp: November 06, 2015, 10:26:00 am
content: Thanks for replies..I also have a space constraint....The board I want to mount this on has a size 90mm x 90mm.... And is already half populated with some logic and relays. I am aware I can use a transformer etc.... But that is not an option hence thinking about the Capacitor Drop... Not a Transformer !Station240: Inverter / Buck Boosts are to step up usually ?BRAndy
230V Snubber  - Page 1
Forum section: electronics / projects

author: Simonv92
author_rank: Newbie
timestamp: April 09, 2020, 05:36:15 pm
content: Hi All!I have a Weller PUD81 solder station, everytime I switch it off I can hear a powerful "bump" in my pc speakers. To solve that problem I want to put in parallel to the Weller switch a snubber.I need some help about R and C values. The Transformer inside is 95W.Thanks all!Simone

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 09, 2020, 08:36:37 pm
content: I can't say exact values but you can start with 470 R (1-2 W) and 0.047-0.1 uF X2-type cap.I think loud bump mean bad design of your PC speaker power supply too.

author: Simonv92
author_rank: Newbie
timestamp: April 09, 2020, 11:27:41 pm
content: Thank you for your reply, I’ll do some test... the speaker psu is a toroidal transformer with a rectifier bridge and some capacitor... I don’t have an EMI filter on the AC line, maybe this can be the problem...

author: trobbins
author_rank: Frequent Contributor
timestamp: April 09, 2020, 11:52:33 pm
content: Try using a different AC mains socket for the soldering iron.
237DT2 Thomson - looking for Datasheet  - Page 1
Forum section: electronics / projects

author: MichalZ
author_rank: Contributor
timestamp: October 17, 2019, 09:02:05 am
content: I'm looking for datasheet or other info about 237DT2 NPN Transistor made by Thomson CSF.

author: amyk
author_rank: Super Contributor
timestamp: October 17, 2019, 12:04:17 pm
content: There are some old SGS-Thomson databooks on archive.org, have you tried looking through them?

author: MichalZ
author_rank: Contributor
timestamp: October 18, 2019, 09:52:23 am
content: Yes, but no luck
24-30pin connector for digital picture frame - Page 1
Forum section: electronics / projects

author: Stealthrt
author_rank: Regular Contributor
timestamp: October 16, 2017, 06:10:51 pm
content: Hey all I have 3 27" lcd panels that I will be making digital picture frames out of and I am looking for advice on what i can use in order to use only 1 cable going to the digital picture frame since it will be on the wall. The less wires the better.Currently I will be purchasing the lcd controller boards for these lcd panels. These boards requires a 12vdc @ 4a to power it.There is also the lvds cable that connects to the back of the panel itself. This usually has 5/3.3vdc going to it.So does anyone have any possible suggestions for a type of cable that has enough pins for the lvds and power? I was thinking of using a HDMI-I cable but I am unsure if it could handle the 12vdc @4a? And keep in mind I would like to find a cable that's not very expensive since ill need about 15-25ft of it per digital picture frame.

author: Stealthrt
author_rank: Regular Contributor
timestamp: October 16, 2017, 08:14:21 pm
content: The reason for just wanting one single cable going to the DPF is because i want to make the actual frame as slim as i can. Nobody likes a 1"+ off the wall sticking out.Each board will connect to a separate panel. So i will have 3 boards in total.The other way around is that i can house all the power, board and whatever else at the power source(floor, behind something) and just have a custom DVI-i breakout pcb made just for the lvds cable(being the DVI-i cable) going to the DPF. But like you've and others have said, it will be tricky yo get the lvds to stretch that far.
24 channel ADC Level shifting - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 04, 2019, 08:57:56 am
content: As part of my tinkering I would like to be able measure the voltages across 16 address lines and 8 data lines in a vintage 5V system. I am considering a 3.3V uP that has lots of analog inputs but only 3V3 tolerant.My sample rate requirement is very low as this is for static analysis.It seems a traditional approach is to use an op amp for the level shift but that's a lot of op amps! Is there a more dense approach? Maybe an analogue switch and multiplex?Thanks in advance

author: Dabbot
author_rank: Regular Contributor
timestamp: June 04, 2019, 09:10:33 am
content: Op amps are also cheap. I'm assuming you want to maintain a high impedance, otherwise I suggest a simple resistor divider on each channel?5V line22KADC channel33KGND

author: Brutte
author_rank: Frequent Contributor
timestamp: June 04, 2019, 09:25:32 am
content: You need a 5v analog multiplexers and then one opamp that will do antialiasing + offset + gain. I think you can control that all with 10-pin uC.If you intend to sample all lines at "the same time" then that could be a bigger problem but if you can make sure no signal transition takes place during sampling channels then that is quite easy.Alternatively, if you just need logic levels of the lines, why not use 5V latched shift registers? These are alsocheap as dirt.

author: Zero999
author_rank: Super Contributor
timestamp: June 04, 2019, 09:50:57 am
content: If the bandwidth is low and the inputs aren't especially high impedance, then a potential divider should do the trick. A capacitor will need to be connected to the ADC input, to provide a low AC impedance to the sample and hold circuit.

author: LapTop006
author_rank: Unknown
timestamp: June 04, 2019, 02:11:49 pm
content: Quote from: NivagSwerdna on June 04, 2019, 08:57:56 amIf you only care about digital data you could just use comparators, or (losing some accuracy around level transitions) even a buffer that's ok with an input voltage above Vcc, random example from a few minutes of trawling Digikay 74HC7014 (at least the Nexperia version, with current limiting resistors), or CD4050 (TI).

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 04, 2019, 04:23:06 pm
content: Thanks for the suggestions... I think I might need to rethink my requirements.
(Removed) - Page 1
Forum section: electronics / projects

author: dcarr
author_rank: Regular Contributor
timestamp: April 06, 2020, 09:44:29 pm
content: (Removed)

author: coromonadalix
author_rank: Super Contributor
timestamp: April 06, 2020, 10:57:07 pm
content: Well your gotchas will be : to have 16 amp at 240 you need combined 32 amps at 120voltAre your ac outlets and breakers are able to match that power consumption ? a mere 3840 watts?16 x 240 = 32 x 120

author: coromonadalix
author_rank: Super Contributor
timestamp: April 06, 2020, 11:03:04 pm
content: I hope your ac wiring in the wall(s) are strong enough .... they wil be pushed to the max, and they can overheat in the walls and maybe you could have a fireThe correct and safest way to do this : would be to have an electrician with the proper transformer redo your electrical box and properly and safely give you what you needThe problem is also the length of you primary wires, are the dephased outlets are near of each other or far away ?Edit : i have the experience to do that but i would never ever do a thing like this:I bought an multi output x-former and made an electrician do an 50 amp outlet, i still got my house insurance and safety ... in my country the insurance company would or could pursue me ...

author: ArthurDent
author_rank: Super Contributor
timestamp: April 06, 2020, 11:53:42 pm
content: Just because something can be done doesn't mean that it should be done. The proper way I think this should be done is to have a qualified electrician rewire the box so you have a dual breaker, half on each phase, so if there is a fault, all power will be removed. Because of the load being 16 amps which is the max continuous recommended for a 20 amp circuit and breaker, I would suggest using a 25 amp (or 30) dual breaker, #10 wire, and a proper 30 amp outlet. Check with an electrician to make sure this would be what is recommended or required by your local electrical code.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 07, 2020, 03:37:37 am
content: The op did not like our answers, op thread removed ??

author: johnkenyon
author_rank: Regular Contributor
timestamp: April 07, 2020, 11:11:00 am
content: Well given that intelligent people learn from the mistakes of others, and therefore most intelligent people aren't afraid to reveal their mistakes, the conclusion we come to is...

author: magic
author_rank: Super Contributor
timestamp: April 07, 2020, 03:17:02 pm
content: ... that the OP didn't think too high of you

author: Zero999
author_rank: Super Contributor
timestamp: April 07, 2020, 03:36:37 pm
content: Quote from: coromonadalix on April 07, 2020, 03:37:37 amTroll? It does annoy me when people do that. Mental note to quote the original post, unless someone hasn't already done so.

author: Simon
author_rank: Unknown
timestamp: April 07, 2020, 05:00:46 pm
content: Quote from: dcarr on April 06, 2020, 09:44:29 pmDon't do that! you will just make yourself unpopular and ultimately get banned.
24/7, 14v-5v DC low noise down converter chip recommendation - Page 1
Forum section: electronics / projects

author: cio74
author_rank: Regular Contributor
timestamp: March 21, 2016, 12:44:43 pm
content: Hello,Could someone please recommend a quality chip to be used in a DC-DC down converter solution, Vin 12-15v, Vout 5V, max 50mA. Noise is a big issue as it would be used to power sensitive to noise equipment. I am considering a LDO solution as SMPS will have too much ripple. In the worst case scenario at Vin 15v and Vout 5v @ 50mA the dissipated power should be around 0.5W which is manageable.It will be used to run 24/7 for years, the simpler design the better.Thanks, appreciate your input.IC

author: mariush
author_rank: Super Contributor
timestamp: March 21, 2016, 02:08:50 pm
content: Have a look at something like LT1761 (available in fixed 5v output version) :http://www.linear.com/product/LT1761Digikey has them in stock :http://www.digikey.com/product-detail/en/linear-technology/LT1761ES5-5%23TRMPBF/LT1761ES5-5%23TRMPBFCT-ND/1629842Farnell also has them (here's the UK store) :http://uk.farnell.com/linear-technology/lt1761es5-5-trmpbf/ldo-reg-100ma-ln-5v-tsot23-5/dp/1663780Linear makes good but expensive chips.
24IO pins vs 24 nodes on CAN line - Page 1
Forum section: electronics / projects

author: mack_30
author_rank: Newbie
timestamp: May 11, 2020, 08:31:39 am
content: I am working on a home automation project, and I have around 24 inputs and 8 relay outputs.Its simple 1 or 0 input consisting of various reed sensors and switches to monitor door, window status or glass shattering.In my current implementation, I have simply used the IO's but I realised there is an enormous amount of wiring involved plus it gets very bulky when all the wires converge to the central monitoring panel.When I compare it with market products, most of the products they tend to follow the same logic (single IO's for the single sensor) and I feel I can simply put a cheap controller on each sensor and communicate everything on single CAN/LIN or RS485 channel.Now my question is more of system analysis rather than a technical one. Is there any added advantage of using a single IO's for single sensor rather than making all of them on a single communication channel.Only drawback I can think of in single communication channel is since everything is dependent on a single communication line, so 1 fault will cause everything to be useless. Is there anything I am missing here?

author: Niklas
author_rank: Frequent Contributor
timestamp: May 11, 2020, 12:20:27 pm
content: Cost! For a home project this is not an issue, but for commercial products it could be a deal breaker. CAN transceiver, more complex microcontroller with integrated CAN controller, external crystal instead of internal RC, connectors with more pins, cables with more wires...

author: Siwastaja
author_rank: Super Contributor
timestamp: May 11, 2020, 01:46:08 pm
content: It isn't either or, it can be a combination.This would be a classical cost minimization problem which you could try to do in Excel, for example.Assign a cost for each meter of wire. Assign cost for the labor of routing those wires.Assign a cost for each module - note it's likely much more than the MCU and CAN transceivers; it needs assembly, programming, testing, casing, etc. It's very hard to produce any "box" for less than maybe $10-$20, no matter how stupidly simple that "box" is, and however small the electronic component BOM cost is.Then group the IOs in different ways, and find the minimum total cost.My take is that design a module which has preferably excess IO, than too little. Say, a CAN IO box with 1 IO connector might cost $20 to build (electronics, casing, assembly, testing), but with 10 IO connectors, it's not $200, but maybe just $25.Now, with excess IO in place but unit cost still as low as it gets, you can decide atinstall timewhether you just leave most IO unused, but if you happen to have a lot of devices there close-by, youdohave the IO available without needing to build a horrible spaghetti nest of chained single-IO modules.