hybridfree/eevblog-posts huggingface dataset:
Buck converter with input current limit - Page 1
Forum section: electronics / projects

author: viperidae
author_rank: Frequent Contributor
timestamp: March 24, 2025, 05:28:23 am
content: I have a strange configuration - It's a garage door opener I've recently automated with a "ratgdo"The control wire from the door opener is designed to be able to power a remote wall panel. It provides ~33V open circuit, with around 30mA constant current. Shorting the output operates the door like a button, or the 'ratgdo' communicates over the line with a serial protocol.I was hoping to draw enough power from the control line to keep the ESP32 running, while also cutting the heat down on the zeners I've had to install to protect the mosfets that drive the line (I think other models of door openers put out a lower voltage, so a 20v gate limit is fine)The control line can almost supply the peak power required by the ESP32's 3.3V @260mA, but only if I keep the control line up at 30V and don't draw more than 30mA.I was thinking a diode, followed by a rather large capacitor feeding a buck converter, followed by some more bulk capacitance, then to the ESP32.Is it possible to configure the current limit inputs in something like an L6902 to limit the input current instead of the output current?

author: moffy
author_rank: Super Contributor
timestamp: March 24, 2025, 05:48:43 am
content: The LM317L can act as a current limiter see page 11 of:https://www.ti.com/lit/ds/symlink/lm317l.pdf

author: David Hess
author_rank: Super Contributor
timestamp: March 24, 2025, 07:16:34 am
content: The diagram for the L6902 shows that the external current sense operates on the error amplifier, so I wonder if moving the current sense from the output to the input would do what you want. It does say that the current sense pins are compatible with Vcc, whatever that means.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: March 25, 2025, 12:01:12 am
content: Quote from: viperidae on March 24, 2025, 05:28:23 am3.3*260m = 0.858W30*30m = 0.9WThat's not much margin, how wide are those peaks, and what is the average?Large Caps will smooth out brief peaks, but if you take a simple 1k and limit inrush to 30mA, you have only 15mA at 15VAnother approach is to use a Linear LED driver set to < 30mA, that has a faster rise time than RC and will still give same current at 25V or 15V, then you can use any suitable buck converter.One example could be AL5809-25P1-7

author: viperidae
author_rank: Frequent Contributor
timestamp: March 27, 2025, 03:35:41 am
content: It idles around 30 to 40mA at 9V. I'd need to double-check but I think this goes via a buck converter down to 5V, then an LDO to 3.3. The peaks are pretty short and are pretty infrequent.I think what I need to do is not current limit the input, but voltage limit it. It's already current limited and I don't want the buck converter to make the voltage sag. Kind of like an MPPT charger with a fixed input target voltage.
Buck converter with pass transistor - Page 1
Forum section: electronics / projects

author: anishkgt
author_rank: Frequent Contributor
timestamp: May 24, 2020, 12:04:29 am
content: Hey All,First time here so i did not find an appropriate category for my Title.I am trying charge a bank of capacitors BCAP0360 in a 3s2p configuration. The Buck converter U1 (AP3211) sets the output voltage at 8.1v and a bypass N-MOSFET Q1 (SQP60N06) to charge at a higher current.Questions:I am just not sure if i have Q1 connected the correct way to function as a bypass transistor for higher current about 50A (Max).Is the inductor necessary here ? Would the inductor be able to handle the rated current ?

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: May 26, 2020, 04:57:11 am
content: The AP3211 has an internal switch, SW pin. Inductor, diode and output caps should be connected to that pin. I suggest you look at the example in the datasheet.
Buck converters under each other - Page 1
Forum section: electronics / projects

author: mrburnzie
author_rank: Regular Contributor
timestamp: October 17, 2022, 11:11:04 am
content: I have a high density board, where my best option is to have two buck regulators one under the other.This means that the regulator of 5V at 750kHz is on the top layer with all its components, and the 3.3V at 1MHz is on the bottom layer.Is this going to create a problem like EMI or similar?

author: Kleinstein
author_rank: Super Contributor
timestamp: October 17, 2022, 04:19:22 pm
content: Normally this should not be a problem. The inductors can have field leakage reaching the other side and this could cause some coupling. It depends on the type of inductor - many are made to have little leakage to the bottum, as this also means less restrictions with the layout.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 17, 2022, 04:40:05 pm
content: Presumably your high density comes with an adequate number of layers (at least 4), in which case inner planes can provide plenty of isolation. You'll have to do the layout carefully with that in mind.Whether you'll have an EMI problem, is entirely dependent on the circuit and layout; impossible to say without both.Tim

author: Terry Bites
author_rank: Super Contributor
timestamp: October 31, 2022, 07:31:45 pm
content: Even for a cheap bobbin, flux densities are very small compared to the main flux path.Try it out with a couple of nasty ebay DC_DC units. You may have to reverse the inductor pins to get a realistic comparison.If its a real worry use shielded inductors, egwww.coilcraft.com/en-us/products/power/shielded-inductors/#/Will they try and phase lock?? That might be handy- or not!
Buck, >2A, Vout 3.8V-, Vin 3.0-5.0, 100% duty cycle, simcom - Page 1
Forum section: electronics / projects

author: nuclearcat
author_rank: Unknown
timestamp: February 11, 2021, 07:34:40 am
content: I'm designing circuit for Simcom SIM7000, it require 3.0-4.2V, but seems really prefer 3.8V, 2A in spikes, when it works in 2G mode.Existing device where Simcom connected provide battery backup 3.0-4.2, BUT also when on power supply provides 4.8-5.0V, and i dont really want to hook Simcom behind TP4056 (to have 3.0-4.2), to not interfere with charging routines.Anybody know good, "close to jellybean", buck converters which can provide required functionality? (best to be available on JLCPCB PCBA, or, in worst case at least not some hard to solder manually)All i found until now is AP3402, but without current "margin".

author: nuclearcat
author_rank: Unknown
timestamp: February 11, 2021, 11:29:40 am
content: Found even better bet.TPS63020 buck-boost, ~4A, and price is reasonable.Also seems FP6165 is not bad.Anything else?

author: ConKbot
author_rank: Super Contributor
timestamp: February 11, 2021, 11:59:36 am
content: Keep in mind a lot of times the converter ratings are for the switches, the TPS63020 is 4A switches, so mind your duty cycles in various modes. It will be sufficient for boosting 3.0 to 3.8 at 2A, but you could run into trouble if say a 2.5A switch converter is used.I've used a 63020 for a single Li battery system before note that the VINA pin has its own internal resistor to VIN, so you only need a decoupling cap, not a trace to it with power on it. (Ask me how I know) And it's pinned out well enough to fit in and out decoupling caps right close to the chip body to get loop area down so they can shunt any switch node ringing easily. Make sure both the in and out decoupling is laid out for a small loop area, as both are the hot loop in different modes of operation.
Buck keeps dying - Page 1
Forum section: electronics / projects

author: sapien
author_rank: Contributor
timestamp: November 15, 2022, 07:25:21 pm
content: I'm trying to design a buck converter with an LTC3892 IC, in dual phase mode.Got it to work (after I added bulk caps on input and output), but keeps dying after a few load transients, or start and stops with its enable ("RUN") pins.Increasing R12 to 5Ohm and C19 to 4.7uF helped, but still didn't solve it completely (still died after something like some more extensive testing, probably still due to load transients).Measured voltage of input and output cap oscillate only a bit with load transients (less then 1V @ input), staying way below the 60V abs max (around 54V max). Can the internal LDO's not cope with the switching noise? Or is it possible my scope didn't pick up on a very short voltage peak, going over 60V?The original values of R12 and C19 are based on the evaluation board:https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/dc2493a.html#eb-overviewAny thoughts on what the problem might be, or advice on how find out what the problem is?Any general tips on improving the PCB layout are also very welcome

author: jonpaul
author_rank: Super Contributor
timestamp: November 16, 2022, 02:55:03 pm
content: schematic missed all power components.Impossible to commentj

author: sapien
author_rank: Contributor
timestamp: November 17, 2022, 10:18:36 am
content: Thanks for your reply! I considered them to be kind of standard, and because of that not that relevant.I've attached all schematics. Also there's a picture ('bottom picture') of the added bulk capacitors, which aren't with the correct spec on the schematic.
Buck regulator design. PMBus - Do I need to use it? - Page 1
Forum section: electronics / projects

author: Fortran
author_rank: Regular Contributor
timestamp: December 03, 2016, 05:15:57 pm
content: Quick background.For quite a long time, I've been thinking of building a 10-20V to 5V DC-DC converter for a pet project.The load may vary between something like 250mA and 10A and I'd like to keep the output ripple below 80mVp-p, but I could always add extra filtering since board-space isn't really limited yet.So today I found theTPS549A20which seems to fit the bill, however I'm not familiar with the PMBus.According to the datasheet it can change the switching frequency, output voltage and do some other nifty things which seems great (if I can get it communicating properly).ButI can't find if I actually NEED to set anything to make it go, or if those pins can be left floating?It might be a stupid question but hey, I'm a bit of a n00b at switching regulators. That's why I'm trying to build one instead of just buying a brick.All the default settingsseemsok as is, but I wouldn't mind being able to tweak them since I'd be using a micro anyway.I just don't want to be forced to code this big scary I2C monster just to get an output.All feedback is welcome! (no pun intended)

author: timb
author_rank: Super Contributor
timestamp: December 03, 2016, 10:32:39 pm
content: PMbus is just I2C which is as simple as it gets, really. If you already have an MCU in your design, it wouldn't be hard to program. Just send a few commands and it's good to go.

author: prasimix
author_rank: Unknown
timestamp: December 06, 2016, 09:24:39 am
content: An analog alternative could beLT3741or evenLT3763. Both has current adjustment, and comes in more DIY friendly packages.

author: Fortran
author_rank: Regular Contributor
timestamp: December 06, 2016, 10:05:51 am
content: I hadn't even considered a LED driver, but that sure does fit the power requirements.It would take a bit more board space, but current adjustment is nice. Might even work as a travelling lab supply.Still haven't found out if the PMBus can be left floating, so I might just make a board with a few different regulators on and see which feels most suited.
Buck regulator module - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: July 06, 2017, 03:10:08 pm
content: I'm looking for a pre-made buck regulator PCB assembly, similar to these sorts of modules from Pololu as an example.https://www.pololu.com/product/2851Vi = 12VIo >= 3.5A continuousVo = 6-9V adjustable.Can anyone recommend or find any such device? Thanks!

author: LabSpokane
author_rank: Super Contributor
timestamp: July 06, 2017, 08:13:51 pm
content: That's kind of a hard to get off the shelf specification. What are you powering?

author: LukeW
author_rank: Frequent Contributor
timestamp: July 07, 2017, 09:49:38 am
content: A linear constant-current regulator that drives a 5W laser diode.I've tried 5V supplies but it just doesn't seem to be quite enough voltage across the laser diode. (Adding the drop across the regulator FET and current sense resistor.)When the laser diode is connected it's only running at about 1.5A, not full design power.The current is set at 3.3A, and gives 3.3A correctly when the load is a 0.5power resistor.(Let's allow a little higher, say 3.5A supply current spec to be sure.)A high-current 12V supply could be used but that's going to substantially increase power dissipation in the FET.

author: LabSpokane
author_rank: Super Contributor
timestamp: July 07, 2017, 10:12:04 am
content: You're just going to have to buy an off the shelf regulator and adjust the feedback resistors.https://www.pololu.com/product/2883This one is extreme overkill, but is in the right range.http://www.intersil.com/content/dam/Intersil/documents/isl8/isl8117.pdfThis is the datasheet for the buck regulator. I am using the Pololu boost regulators for a low volume application and they are well made and meet their specs. Not cheap, but no fuss.

author: Zero999
author_rank: Super Contributor
timestamp: July 07, 2017, 10:39:02 am
content: Quote from: LukeW on July 07, 2017, 09:49:38 amThen why not replace the linear current regulator with a constant current buck regulator? An LED driver module is probably perfect for your application and be more efficient then an SMPS + linear regulator.

author: LukeW
author_rank: Frequent Contributor
timestamp: July 07, 2017, 03:36:59 pm
content: Care to suggest something that is available fairly rapidly, cheap, off-the-shelf, capable of 3.4A? TTL PWM/enable input would be nice to have.

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2017, 12:06:12 pm
content: Quote from: LukeW on July 07, 2017, 03:36:59 pmhttp://www.dx.com/p/dc-dc-automatic-buck-boost-constant-voltage-constant-current-module-blue-5a-258020#.WWIb0lGQyHs
Buck with floating supply - back-2-back High NMOS (x2) to prevent reverse flow? - Page 1
Forum section: electronics / projects

author: snoop33
author_rank: Contributor
timestamp: June 02, 2022, 10:45:02 pm
content: LTSpice says it works, with the same voltage drop over the second MOS.My gut feeling is something is wrong because the floating voltage isn't around the gate and source but the gate and drain of the second MOS. I'd expect the upper MOS to work correctly due to the body diode of the lower MOS but can't get by head around the lower MOS working.Also, nobody seems to be doing it, which is a worry!
Buck/boost LED driver help  - Page 1
Forum section: electronics / projects

author: Tangent_Tracker
author_rank: Regular Contributor
timestamp: June 05, 2023, 11:46:48 am
content: Hi folks, can anyone help me identify this IC used to drive some XHP LED's? I can't tell if in buck or boost, there is no diode so I assume it has a built in FET to provide the pump, so to speak...Cannot find any info, maybe someone can help track the IC down?

author: kilobyte
author_rank: Regular Contributor
timestamp: June 06, 2023, 09:23:52 am
content: Searching on LCSC gives me the ME2187 as a result and the Logo is matching.
Generating multiple clocks for Bucket Brigade Devices - Page 1
Forum section: electronics / projects

author: ErnstHot
author_rank: Newbie
timestamp: December 29, 2014, 12:06:50 pm
content: I am planning on making a stereo bank of individually tuned comb filters for an audio effect, using a bunch of bucket brigade devices (MN3207). This means I will need to generate somewhere from 6 to 16 individual clock signals (and their inverse signals), running a couple of kHz to a couple of MHz for the BBDs, depending on how large I want the bank to be.>=12 bit counters on a >=48 MHz clock would offer a reasonable resolution (+/- ~4 cents) for the frequency range I need, if my calculations are correct. (I plan on driving the BBDs beyond their specs using a 4049D hex inverter)So how do you generate those clocks as cheap and simple as possible?It doesn’t need to be absolutely jitter free, or I would just do the whole thing in software. I want all the clocks to be digitally controlled from an MCU.Any help would be much appreciated!

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 29, 2014, 04:28:44 pm
content: Maybe dedicate a small 8 bit microcontroller to the task of generating clock signals?

author: trophosphere
author_rank: Frequent Contributor
timestamp: December 29, 2014, 07:37:30 pm
content: Might want to take a look at theSi5351B or Si5351Cto see if it fits your specification.

author: ErnstHot
author_rank: Newbie
timestamp: December 31, 2014, 12:04:17 pm
content: Thank you, both of you.The Si5351 looks good, but I think I'll go with an MCU because I'll also need a DAC for controlling the feedback of the comb filters, so I might be able to kill two birds with one stone if I can find an MCU with a suitable timer and DAC.
Bucking Transformer help - Page 1
Forum section: electronics / projects

author: Laurie
author_rank: Newbie
timestamp: March 25, 2016, 04:43:05 am
content: G'day again!I thought i would play around with a small project today and was hoping you guys could help me..I would like to build a step down (bucking type) transformer to run an old valve amplifier i have rebuilt that requires a 220VAC Supply.Currently my Mains voltage sits at around 251VAC.So what i have is an old toroid transformer I have removed from an old subwoofer. The transformer has a single primary winding and 2 secondaries.The secondary winding are 15V-0-15V 0.16A and 32V-0-32V 1.48ASo i would like to use the 32V tap on the 2nd secondary and blank off everything else.I have the Schematic that i would like to use, but my questions are; Will this drop the Voltage to much? and how do i work out the polarity of this secondary?

author: dom0
author_rank: Super Contributor
timestamp: March 25, 2016, 07:24:28 pm
content: Simple: Connect it, measure. If it's 280 VAC, reverse connections. If it's 220 VAC the connections are right.A 100 VA toroid like you have there is already a pretty stiff voltage source ; shouldn't give any problems.

author: Stray Electron
author_rank: Super Contributor
timestamp: March 25, 2016, 11:58:07 pm
content: Just be aware that if you connect the secondary back to the primary (bucking or boosting) that your output will no longer be isolated from the AC line and you could be creating an electrical shock hazard, particularly if your equipment uses chassis ground as a voltage return.

author: Laurie
author_rank: Newbie
timestamp: March 28, 2016, 01:58:42 am
content: Quote from: dom0 on March 25, 2016, 07:24:28 pmThanks, I done exactly that and came out with a high reading the first time so reversed polarity of secondary and have a near perfect 30V drop now.I still have the original 1.5A Fuse wired in with the original power switch and Fuse box from the old subwoofer, I have just cut that section of mounting plate out and used it as front panel on my new box....I have mounted power point to this also.Question, Should the mains fuse be in series which is Active with the secondary of transformer? does it make a difference...And what current rating would this be now?

author: Laurie
author_rank: Newbie
timestamp: March 28, 2016, 02:04:21 am
content: Quote from: Stray Electron on March 25, 2016, 11:58:07 pmI understand the transformer is no longer a point of isolation, it has all been built into a wooden box with all connections insulated correctly...including mains Earth straight in and out via power point...is there something beyond my understanding here that I need to worry about?

author: Seekonk
author_rank: Super Contributor
timestamp: March 28, 2016, 05:22:09 am
content: If the transformer is near saturation voltage it may be better to connect it as an auto transformer, 280V configuration with 280 connected to 250V line.
Budget DSO / Handheld DSO - Page 1
Forum section: electronics / projects

author: Jon86
author_rank: Frequent Contributor
timestamp: November 09, 2013, 10:21:25 am
content: So I'm thinking about buying a scope quite soon because what I can do in terms of electronics is very limited at the moment. My budget going to be under £200, and I know this is pretty limiting but it's what I'm going to have to deal with.I'm sure a lot of people will recommend analog scopes, but after using them for a couple of months, I'm starting to hate them...I definitely want to try and get a half decent digital scope, and I've been looking at the cheaper hanteks and siglents, and also the Owon HDS1021M.Bandwidth isn't a big issue as I'm only going to be doing relatively low frequency stuff anyway (a couple of Mhz).Can anyone suggest anything in this price range? I don't need anything great, just an average scope.

author: Mrdjdean
author_rank: Newbie
timestamp: November 09, 2013, 11:20:26 am
content: Hi JonI know you said your budget was under £200, but recently while i have been looking i found this;http://dx.com/p/rigol-ds1052e-5-6-tft-lcd-50mhz-2-channel-digital-color-storage-oscilloscope-30573?tc=GBP&gclid=CIeauf_J17oCFfMdtAod7mYASgIt has been reviewed and recommended endless times here, good quality and by the way you have described your requirements sounds like it fits in perfectly. Free shipping too for us in the uk.As i said, a tad over your £200 but an absolute bargain, would be good to hear what you end up going for as I'm in the same boat as you.All the bestDave

author: Whuffo
author_rank: Regular Contributor
timestamp: November 09, 2013, 01:50:33 pm
content: I bought my Rigol DS1052 DSO from Aliexpress - a vendor on there called "sunrun store" had them for $285 US. Applying the Gizmo update turned it into a 100Mhz DSO.This should be within your budget. Stay away from the "pocket" DSOs or the USB DSOs - they work, but not very well. Consider the DS1052 as a minimum entry point.

author: Jon86
author_rank: Frequent Contributor
timestamp: November 09, 2013, 11:38:11 pm
content: Thanks for the advice, I think I'll save the extra bit of cash, wait a while and buy myself a real oscilloscope, not a little cheapo. The DS1052 it is!

author: chasxmd
author_rank: Contributor
timestamp: November 10, 2013, 12:06:43 am
content: I think the Rigol will treat you fine but let me offer a tiny bit of advise: If you don't have your heart set on the Rigol and have any ability to save and wait another few months to get something you'd rather have, you should. I kicked myself for quite a while for not saving to buy what I really wanted.. a MSO. I do that to myself on test equipment every so often.
budget Night vision scope / IR tester   - Page 1
Forum section: electronics / projects

author: juliancook
author_rank: Newbie
timestamp: March 31, 2013, 08:46:11 pm
content: OK after watching the EEVblog videos over the last few weeks and feeling good that I understand some 30% of what is said and not fully clueless on the rest, I feel after 20 years of not doing electronics it might be fun to play around a bit, so the mother of all invention being necessity, my necessity was to be able to test a remote control, to see if it was working, the pcb is not easy to follow as its a chip with some gunk on and a bunch of buttons. I had a spare CCTV camer hanging about and plugged it into my TV and shot the suspect remote and could see the IR output, so the remote is fine, its just the portable DVD player thats messed up. So i have a screen that works and a camera that works, I dont need the DVD player but it might be fun to have a night vision scope, I just need to get them both talking to each other.My first problem is that I have a video output and a screen, the screen needs to get the output, so i am guessing that i need some sort of video chip to take the video output from the camera to the screen, so my question after all that is, what should I be looking at
Buffer to drive 80nF at 28Mhz - Page 1
Forum section: electronics / projects

author: Boscoe
author_rank: Frequent Contributor
timestamp: April 13, 2018, 09:14:01 pm
content: Hi all,Looking for some advice o a n image sensor project driving the horizontal clock. The clock has a humongous 80nF capacitance and needs to be driven at 28Mhz 12Vpp!So far, I've looked at high speed comparators/amplifiers driving A MOSFET or BJT inverter however the BJTs aren't fast enough and the MOSFETs gates require too high pulse currents for the amplifiers that are fast enough.I would rather keep away from CCD clock drivers unless that come in single channels or are matched. Mismatch in timing is a nightmare to compensate for in the hardware. I MOSFET gate driver is perfect apart from they aren't fast enough.ThanksBoscoe

author: Ian.M
author_rank: Super Contributor
timestamp: April 13, 2018, 09:32:59 pm
content: Quote from: Boscoe on April 13, 2018, 09:14:01 pm80nF at 28MHz has an impedance of 0.07 ohms, and would need 85 Amps to drive it with a 12V pk-pk sinewave. To get reasonably squarish edges, you'd need at least five times that current and an output stage that's broadband and good up to around 150MHz, so you are well into multiple Kilowatt radio transmitter territory. Even 1% losses in the sensor would result in 25W dissipation and probably fry it.Are you *SURE* there isn't something wrong with your numbers?

author: Boscoe
author_rank: Frequent Contributor
timestamp: April 13, 2018, 09:37:13 pm
content: Quote from: Ian.M on April 13, 2018, 09:32:59 pmI'm sorry, yes! I was reading the wrong clock capacitance! Thank you for your reply.
Buffering/Decoupling AC-DC 5V Power Line - Page 1
Forum section: electronics / projects

author: awef
author_rank: Contributor
timestamp: September 20, 2017, 05:52:13 pm
content: I'm powering my PCB from a USB power wall wart (220VAC -> 5VDC). I believe the USB power supply (iPhone style) is a Switch Mode supply since it's not large/heavy.When a high power motor on the same AC Circuit starts, my 5V line can vary +/-10-15V for 10-20ms. It looks more like line noise/ringing than a "square wave pull down" when I look at my scope output.Can AC noise really affect my DC power rail that much?I've tried putting a 10mF capacitor across 5V/Ground, but it seems to make little difference.Are there common ways to decouple my PCB/Power Supply from my nasty neighbor?

author: David Hess
author_rank: Super Contributor
timestamp: September 20, 2017, 11:42:57 pm
content: The USB power wall wart was just cheap and has poor line regulation. A better one would not have that problem. You could try attaching a large aluminum electrolytic capacitor to the output.

author: awef
author_rank: Contributor
timestamp: September 21, 2017, 09:49:01 am
content: I tried another more expensive SMPS but had the same effect.I'll try the capacitor idea.Is there anything in a power supply specification that I could look for which would imply better line regulation? Or perhaps to ask a different way... If I can't find a good power supply and need to design it myself, what should I definitely not miss?I've made a few buck/simple smps boards before by following designs, but never had to address this particular problem in the past.

author: David Hess
author_rank: Super Contributor
timestamp: September 21, 2017, 12:39:43 pm
content: Quote from: awef on September 21, 2017, 09:49:01 amIt is an aspect of line regulation. Current mode designs are better for this because of their feedforward negative feedback. USB chargers and a lot of consumer gear is just incredibly cheap.Another way to handle it is to add a shunt regulator to the output which might be as simple as a zener diode.Double check that what you are measuring is real. The Y class EMI suppression capacitors to ground might be coupling common mode noise into the ground of your test instrument.

author: awef
author_rank: Contributor
timestamp: September 21, 2017, 05:33:32 pm
content: Thanks for your thoughts David!I'm not familiar with the concepts regarding Y-Class Capacitors/Common Mode Noise Coupling, but I'll try to look around and see if I can figure out the basics.
Buffering a scanned row of data - Page 1
Forum section: electronics / projects

author: HendriXML
author_rank: Super Contributor
timestamp: August 04, 2020, 10:00:27 am
content: I'd like to build a application that scans row by row data while the user inserts a encoded key.Each row has a trigger signal, and some data signals which are valid at the trigger moment until a milli seconds later. The row data is fed to a Arduino (Mega 2560), it will probably be fast enough to handle it. Reading the last data signal before it is lost. But I think buffering this data is more reliable.I think using this ic (cd54hc377) will do the trick (using the trigger as the clock signal). It also has opportunity to ensure no new trigger can mix two rows. (Data enable)https://www.ti.com/lit/gpn/cd54hc377Would this ic be a good choice, or are there more suitable ones?

author: OM222O
author_rank: Frequent Contributor
timestamp: August 04, 2020, 10:05:37 am
content: If it doesn't have to be analyzed on an mcu, just dump all the data to a PC and let that handle everything for you. Much more options for filtering, averaging, rejecting bad data, having a lot of memory for the buffering, etc etc.

author: HendriXML
author_rank: Super Contributor
timestamp: August 04, 2020, 10:11:06 am
content: It needs to be handled on the mcu. The signals are ok and the speed at which rows follow each other is dependent on how fast the key is inserted, but the mcu should be able to handle them with ease.

author: Unixon
author_rank: Frequent Contributor
timestamp: August 04, 2020, 10:48:47 am
content: ATmega2560 has entire 8-bit ports available for I/O. If you allocate all data lines to a single port you can read entire port with a single operation on a trigger interrupt. This wouldn't take that many cycles to make it unreliable. Since all operation depends on timings I can't say for sure that such buffering is not required, but I honestly doubt it.

author: HendriXML
author_rank: Super Contributor
timestamp: August 04, 2020, 11:01:48 am
content: Quote from: Unixon on August 04, 2020, 10:48:47 amSounds interesting, will investigate it!It's probably best to do both.The insertion of the key can also be slowed down, but the reliability should not depend on that too much.
Buidling a RS232 PM9080 Fluke Optical Cable - Page 1
Forum section: electronics / projects

author: ZGoode
author_rank: Frequent Contributor
timestamp: August 09, 2024, 03:28:51 am
content: Howdy y'all,I'm working on building a copy of the Fluke RS232 optical cable for the scopemeters, but am running into some difficulties. I started based off of the design by BVKSound, but haven't been able to get it to work. Does anything look off in this designhttps://github.com/bvksound/Fluke_PM9080. So far, it seems like the TX line isn't creating enough of a voltage difference, since when measured with my scope it only shows a 1V potential on the IR emitter. Does anything look out of place or blatantly wrong in what I have here?

author: ZGoode
author_rank: Frequent Contributor
timestamp: August 09, 2024, 07:19:33 am
content: Well, I think I found one problem, but I still can't get it to work. I think I flipped the RS232 connector around weird, but it still isn't working even after flipping it around with a cabled connector. This should be easy, if I can get it to work on UART, I should be able to get it working with RS232
Build a simple Vacuum Tube amplifier - Page 1
Forum section: electronics / projects

author: NeoRecasata
author_rank: Newbie
timestamp: April 06, 2013, 02:57:03 am
content: Build a simple 12AU7 tube ampI am trying to build a tube amp that's using a 12AU7 tube and an IRF610If your interested to build one here's the linkhttp://diyaudioprojects.com/Solid/12AU7-IRF510-LM317-Headamp/NOTE: this is not my linkhappy building!

author: c4757p
author_rank: Super Contributor
timestamp: April 06, 2013, 09:14:54 am
content: That is the smallest voltage overhead I've ever seen a traditional triode run with. How is the distortion? You ought to try one of the special low voltage tubes that were specifically intended for 12V operation (car audio, etc.)

author: NeoRecasata
author_rank: Newbie
timestamp: April 06, 2013, 02:59:31 pm
content: I don't have the other parts in my local electronics shop, but i have the tube
Build a Time Marker Generator - Page 1
Forum section: electronics / projects

author: Giovanni28
author_rank: Contributor
timestamp: October 27, 2015, 09:02:06 pm
content: https://copy.com/C8EdXSOi14wPCOgUI ask you for advice, the schematic in the figure is valid to build a Time Marker Generator? Is there an IC equivalent to the LM2240?

author: Paul Price
author_rank: Super Contributor
timestamp: October 27, 2015, 09:15:11 pm
content: The very legacy LM2240 uses an R-C circuit which creates delays would can be divided down in 1 to 255 in period, the output of this chip is in the form of a square wave not a marker blip and the accuracy of the output pulse train would depend on the stability and accuracy of the RC circuit components used by the LM2240. This chip's other limitation is the binary division output giving 1-2-4-8-16..etc ratios that are not be suitable for setting 1-2-5-10-100 etc pulse delay values.I simply use a PICC18 MCU chip to generate blips or continuous pulses by creating the most simple of program: just a few lines of code looping and counting a sequence of NOP instruction cycles between toggles of a GPIO port pin using the highly stable and accurate internal system clock frequency of 64MHz.Any other MCU or a pre-fab Arduino setup with a small PPM tolerance crystal for a rock-solid system clock might do just as well and would be easily programmable to output the time marker pulses you want.

author: Giovanni28
author_rank: Contributor
timestamp: October 28, 2015, 03:54:52 pm
content: Thank you very much.

author: LaserSteve
author_rank: Super Contributor
timestamp: October 28, 2015, 03:59:47 pm
content: I have a simple TTL circuit at home in a book that gives the 1:2:5:10 sequence driving a DAC for scope use, I'll try to remember to scan it for you.The 2240 is obsolete, and not fun to use..Steve

author: PaulAm
author_rank: Frequent Contributor
timestamp: October 28, 2015, 04:09:25 pm
content: If you want to just throw something together, get a canned crystal oscillator for 10 or 20 MHz and feed it into a series of decade counters to get the frequencies you need. Run the output into a oneshot to get the timing pip.Or, do it all in software with an Arduino or other small processor. If you do that, you'll probably spend more time on the UI than anything else.
build change - Page 1
Forum section: electronics / projects

author: p.larner
author_rank: Frequent Contributor
timestamp: March 06, 2024, 11:50:25 am
content: heres the schematic split into 3 parts for a chinese 0-30v 5a psu with tap switching,can it be made using a coupe of taps from a multitap main transformer to run the whole psu or is the auxillary transfo needed?,the almost original schematic is the 2nd one..

author: p.larner
author_rank: Frequent Contributor
timestamp: March 07, 2024, 12:14:46 pm
content: ie looking at the pdf similar but not the same,can l1 be done away with so just use taps from l2 instead for the relay switching.

author: p.larner
author_rank: Frequent Contributor
timestamp: March 08, 2024, 07:28:16 pm
content: wont that cause a short?

author: p.larner
author_rank: Frequent Contributor
timestamp: March 09, 2024, 04:07:13 am
content: can anyone give me an answer?.

author: Andy Chee
author_rank: Super Contributor
timestamp: March 09, 2024, 05:50:44 am
content: If you improve your english grammatical structure of your questions, then maybe someone will be able to comprehend the gist of your query.From my understanding of your question, you are asking whether transformer tap switching will create a shorted winding, however, it is difficult to parse your sentence structure to be sure whether this is what you're asking.
Build Project help testing RJ45. - Page 1
Forum section: electronics / projects

author: challie2
author_rank: Contributor
timestamp: May 01, 2018, 08:11:00 am
content: Good Morning,Could someone help me with a build.Looking to build a multichannel selector circuit board.The concept is that I want to be able to have 9 channels, that can be individually selected with a toggle push button, I want to be able to test RJ45 cables on a Multimeter to record impedance, it is for no project in particular but the engineering council I adhere to have standards in place that require me to do so.I need it to provide impedance recordings as such cores 1-1, 2-2, 3-3, 4-4 and so on, we do not tend to use crossovers.Unfortunately I cannot use an RJ45 banana plug as this shows the lowest impedance across all cores 9 there could be a break or a high impedance that would be hidden in this test additionally I do have a PC cable tester, but this only shows a Red LED lamp for the pinouts and does not provide a ohm reading.Would appreciate any help perhaps there is even a multi meter adapter that will provide the facility of showing each of the cable individually?Kind RegardsJamie Newman

author: ebastler
author_rank: Super Contributor
timestamp: May 01, 2018, 08:38:39 am
content: If you want to connect to a multimeter and take readings manually, I would be inclined to use a mechanical rotary switch. The contacts might degrade over time and add some resistance, but assuming that this device sees occasional use, probably not a major problem in practice. Alternatively, you could use an analog multiplexer, either controlled by an up/down counter or a small microcontroller.If you are only concerned about broken connections and can ignore the risk of shorts between adjacent wires, you would need a selector on one end of the cable only, and could connect all pins in parallel on the other end.(If, on the other hand, youdoneed to look for shorts, that would stronly suggest a microcontroller to control the device. Stepping through all the "wrong" terminals for each position of the main selector would get annoying really quickly with fully manual control. In that case, the microcontroller would have to do the resistance reading as well -- at least a coarse one to check for shorts.)

author: sokoloff
author_rank: Super Contributor
timestamp: May 01, 2018, 10:43:55 am
content: If you only need rough, uncalibrated measurements, you could consider using a system like this:https://hackaday.com/2011/07/24/using-an-arduino-to-measure-inductance/to automate the measurements with a microcontroller.
builder wanted for project - Page 1
Forum section: electronics / projects

author: surfguy
author_rank: Newbie
timestamp: November 30, 2023, 07:38:55 pm
content: HiLooking for a competent builder to build a dumb waiter control unit using arduino board.board will control programed 3 stop height,ground /1st floor/2nd floor.would allow for 240v relays to handle motor load.3 wall mounted button panel allowing.emergency stopcallsend to floorbuilder will quote for job please and freight unit to me if this is interesting to you.surfguy4u@hotmail.com
Building a Brushless DC (BLDC) Motor - Page 1
Forum section: electronics / projects

author: andrew_c
author_rank: Regular Contributor
timestamp: March 01, 2015, 12:32:28 am
content: Good morning/evening/afternoon all,I would quite like to build my own BLDC motor - for giggles really but I can think of a few uses. I don't really have any desired torque/rpm, though I guess anything from 100 to 1000 rpm would be a nice start. I would like to stay away from winding my own stator and instead use off the shelf inductors around the outside of the internal spinning permanent magnets (pic). I've got some off the shelf 3 phase BLDC motor controllers so no worries there. I just can't figure out how many magnets/inductors, what strength magnets, what micro-henry inductors etc.. Could anyone give me a nudge in the right direction?Thanks a lot guys!Andy

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 01, 2015, 12:47:27 am
content: http://www.gobrushless.com/shop/index.php?app=ccp0&ns=catshow&ref=diy+brushless+kitsctrl-ftools

author: langwadt
author_rank: Super Contributor
timestamp: March 01, 2015, 12:57:58 am
content: http://www.tcrconline.com/documents/Brushless/Brushless%20Motors.pdf

author: andrew_c
author_rank: Regular Contributor
timestamp: March 01, 2015, 01:30:41 pm
content: Two fantastic links there, thank you very much!

author: nuno
author_rank: Frequent Contributor
timestamp: March 01, 2015, 02:35:06 pm
content: http://endless-sphere.com/forums/viewtopic.php?f=30&t=30061http://endless-sphere.com/forums/viewtopic.php?f=30&t=46476http://amazingdiyprojects.com/
Building a DIY nano ampere current meter - Page 1
Forum section: electronics / projects

author: fracton
author_rank: Contributor
timestamp: November 30, 2024, 06:20:59 pm
content: We recently had an issue with a 6 1/2 digit digital multimeter from Keitheley at work. As it still seems to be under warranty we had to send it back to the vendor for repair. However, that got me thinking about a DIY current meter that can measure 10 - 1000 nA level currents.I am thinking about using the following for build my nanoamp meter:- OPAMP: an LMC6082 or LMC662,- MCU: arduino uno + ADS1115 for a 16bit ADC or a raspberry pico pi (2040)- LCD screen to put together the ourputAlso, see this thread that I posted on themetrology board.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 01, 2024, 05:15:41 pm
content: A simple transimpedance amp might suffice but It'll be hard to build one with the same spec as the Kiethley. Watch out for stray capacitance at the input!If you're working with DC amps and not in a hurry for your reading, use an integrator circuit. integrate, hold, measure and reset. Decent caps are so much cheaper than very high value resistors. Integrators are inherently stable unlike TIAs.Also see the discussion on kelvin switching for TIAs. At low currents reed relays are a must.https://www.analog.com/en/resources/analog-dialogue/articles/programmable-gain-transimpedance-amplifiers.html

author: Gyro
author_rank: Super Contributor
timestamp: December 01, 2024, 05:37:44 pm
content: Note that this is effectively a [EDIT: partial] double post of a thread in the Metrology section (as the OP referenced), that is getting a reasonable number of replies...https://www.eevblog.com/forum/metrology/diy-nano-ampere-current-meter/@OP: Please don't do this - it leads to duplication and waste of time and effort, as seen above. It won't win you friends.
Building a Multiple Module Connection Box - Page 1
Forum section: electronics / projects

author: RJSV
author_rank: Super Contributor
timestamp: July 07, 2020, 06:43:29 am
content: Hi I've been designing an experimenter's box having a misc set of five circuit boards, taken out of small toys.For selections each 'Channel' input has a 1 of 12 rotary or rather a six position having also a SPDT toggle.So, for example CH4 is a 'Singing Bird' with motion detecting sensor input. Now that input can be from any output, excepting itself.An experiment could involve connecting to a latch, such as CH2 in my design. Today, I am wiring in 12 separate outputs for the various (5) channels. The toy Bird has 3 outputs, including Audio Out, and two pulsed outputs driving solenoid coils: the coils move the Bird'sbeak and neck during a few moments of song.Readers, if you can follow this, you see that those three outputs create interesting / complex signals that are yet again available to any next device (channel). I even realized that CH5,. a "dog barking' audio circuit taken out from a stuffed toy will accept an AC waveform, to the 3VDC power leads, within reasonable reverse voltage limits, as the original toy used reversed voltage for control of a separate motor. So it worked !Now that outcome was unexpected; having the "dog" circuit playing the bird chirps in a sort-of modulation effect. I figure there are more than 500,000 ways to dial in your semi-random layout order.Let your 6 year old future engineer go hog wild, dialing those 5 rotary switches in harmless interconnections !
Building a pocket oscilloscope - Page 1
Forum section: electronics / projects

author: z_tjona
author_rank: Newbie
timestamp: May 22, 2015, 04:20:57 am
content: Hi, I'm new in this forum,I just started with this proyect in my university: I need to build an oscilloscope with a TFT. it requires a 200Khz frequency, and to calculate Vrms.My principal question is what could be the best way to control it ?An fpga or a microcontroller?I have a STM32f4discovery but, I began to doubt because I though that maybe the uC can't reach the frecuency (i haven't tried with the Stm yet)Any idea or some experience would be forever appreciated.ajaajaj

author: Skimask
author_rank: Super Contributor
timestamp: May 22, 2015, 04:41:26 am
content: You asking because there isn't any knowledgeable people around your "university"?Time to change majors...

author: Marco
author_rank: Super Contributor
timestamp: May 22, 2015, 07:12:13 am
content: In the absence of knowledgeable peopleLTG. The fourth link has source code for the STM32F429-Discovery-Board.
Building a power amp from vintage components - Page 1
Forum section: electronics / projects

author: capt bullshot
author_rank: Super Contributor
timestamp: April 25, 2017, 02:00:34 pm
content: No, not another tube amp, it's a transistor amplifier.It is build using some large transistor modules rated at 1000V / 150A, these went normally into variable frequency drives or power inverters. Not particular suitable for a linear power amplifier, but ... it works.The project isn't finished yet, I've got a set of three working power amplifer "modules", each using one of these large BJT blocks, and some support circuitry.Bandwidth isn't exactly audio (DC to 10kHz), output power is huge and sustained (not like your home audio amp that starts burning if you run it at nominal power for a prolonged time)See the thing here:http://wunderkis.de/pwramp3/

author: Codebird
author_rank: Regular Contributor
timestamp: April 25, 2017, 02:08:18 pm
content: What is this monster supposed to be used for? Competitive sub-woofer driver? Are you building a base cannon?

author: capt bullshot
author_rank: Super Contributor
timestamp: April 25, 2017, 02:12:55 pm
content: Nah, no audio. Maybe hooking a 3 phase transformer to it to have a lab AC power source, spinning an AC induction motor the most inefficient way, generating lots of heat, ...

author: cat87
author_rank: Regular Contributor
timestamp: April 25, 2017, 02:23:30 pm
content: Looks awesomely powerful.Have you tried doing some measurements to see the actual bandwidth those monster transistors have ?

author: capt bullshot
author_rank: Super Contributor
timestamp: April 25, 2017, 02:31:59 pm
content: No, I didn't measure their bandwidth alone. According to the datasheet, they should be pretty fast (switching on/off in the single digit µs range). With my amplifier, the BW limit is in the control circuit. From my experiments, I believe the transistors should be able to reach 100kHz in this particular configuration. At some point I stopped to optimize the driver / control loop for BW.

author: MagicSmoker
author_rank: Super Contributor
timestamp: April 25, 2017, 10:14:50 pm
content: I have a pile of old BJT modules myself, so this is an especially interesting project to me!Note that you can add emitter degeneration if you use "single" BJT modules, rather than the half-bridge configuration. I also would be wary of relying on inductance in the base drive circuit to quell oscillations in an emitter follower.