hybridfree/eevblog-posts huggingface dataset:
power led circuit doesn't work - Page 1
Forum section: electronics / projects

author: PuzzledQuiet
author_rank: Newbie
timestamp: August 22, 2024, 07:15:27 pm
content: I'm a hobbyist, not an engineer or student, and this is my first schematic. So maybe the problem is obviouseven by looking at the schematics but I'll just add some descroptionThis circuit is meant to be 4 power LEDs being controlled by an Arduino through a mosfet.The XL6009E1 module is an adjustable boost converter similar to this:https://components101.com/modules/xl6009-dc-dc-step-down-voltage-regulator-module. It's set to 22v.The battery is a 3.7v-4..2v 2200mAh lithium-ion battery. its terminals are connected to the module's input termninals and all of the VCC and GND symbols in the schematic are directly connected to the module's output terminals.The weird powering scheme which probably is the cause of the problem, is because:1. LEDs drop around 3v each and so can't be driven by the battery directly, so I thought I boost the voltage and then build a constant current source which provides around 200mA.2. Arduino should be driven with the same power source and I read that it shouldn't be powered through 5 volts pin and it's better to use the Vin pin which is connected to an internal regulator itself, and I have only LM317 regulators.The problem is that leds turn on perfectly as long as arduino is not connected to the circuit and the mosfet is triggered manually, but as soon as I add the arduino, it loads down everything, although the measured current through the Vin pin is only 60mA.Replacing the Arduino with a 100 ohm resistor to the ground has the same result but resistors higher than 200 ohm don't have any negative effect and the leds remain on with full brightness.Removing the mosfet and driving the leds directly by the constant current source is exactly the same as driving them by the mosfet.Connecting a constant current source and a constant voltage source in paralled to a power supply rail feels kind of weird to me, and I'm afraid even if I fix this with circuit with some tweaks, I just shouldn't power think like this

author: Benta
author_rank: Super Contributor
timestamp: August 22, 2024, 08:58:36 pm
content: Your LM317 is not wired as a current source. Fix that first (hint: the ADJ pin is the ouput).
Power LED Driver - Page 1
Forum section: electronics / projects

author: 4beowulf7
author_rank: Newbie
timestamp: July 31, 2015, 07:37:20 am
content: Hello everyone,I have designed a Power LED Driver. It's a simple circuit but if you want to power some LEDs with a power rating of 1-5W, this circuit may help you.https://tr.scribd.com/doc/272548178/Power-LED-DriverGreetings
Power-line communication coupling into scope input - Page 1
Forum section: electronics / projects

author: Xevel
author_rank: Contributor
timestamp: January 22, 2015, 09:36:59 am
content: Hi!I have two power-line communication devicesTPL-307Ethat I use to get internet in a part of he house that cannot get a good wifi (thick stone walls).The problem I have is that the communication of these devices end up showing on my oscilloscope (previously DS1102E, now MSO1074Z-S).I can see it clearly when I hook up the test probe to the ground on the scope facade without hooking up the probe ground. This was how I managed to get a good enough look at it to then identify it.Most of the time it's not a problem, but in some cases even with a reasonable ground connection to the device under test, I can see it creep up and make it difficult to see what I'm looking for.The carrier frequency is 3MHz.I am not sure how this signal couples into the probe (electromagnetic? through the scope power supply?), so I thought I should try to remove the signal from the power of all the devices I have around the lab. The adapters are not in the lab, so there is no need for the signal here.Save for putting a huge 240V - 240V isolation transformer to isolate my lab from the rest of the house, does anyone have an idea how I could safely filter this signal at the wall socket level, without killing the signal for the rest of the house?Thanks!

author: nctnico
author_rank: Super Contributor
timestamp: January 22, 2015, 12:19:15 pm
content: How is your grounding? Do you have properly grounded outlets?

author: Xevel
author_rank: Contributor
timestamp: January 22, 2015, 01:32:34 pm
content: House has < 10 years electrical installation, and I just tested that ground is indeed good.

author: SeanB
author_rank: Super Contributor
timestamp: January 22, 2015, 04:51:33 pm
content: Take a large ferrite toroid ( or an old CRT TV set LOPT transformer core ) and wind the scope power lead through it as many times as will fit ( more than 5 turns) and try it again. You basically want to make a big common mode choke. Otherwise you can use a large 15A rated mains filter in a case and wire the bench power through it.

author: eejake52
author_rank: Contributor
timestamp: January 22, 2015, 04:56:07 pm
content: This problem was also observed for early home automation schemes that used the power line as a carrier. If you search for X10 filters you can see numerous suggestions. Many years ago, I made several ofhttp://www.nomad.ee/micros/levitron_6287_schematics.pngand they appeared to work.Jake

author: richard.cs
author_rank: Super Contributor
timestamp: January 25, 2015, 09:18:35 am
content: These things send data differential mode between line and neutral, 100mW spread between 2 and 30 MHz (to 70 for the high speed ones). To not mess up the rest of the house your filter should have the series element first. Bear in mind that this stuff radiates off the wiring horrifically so it may not be coupling in just by conduction.
Power Line Communications - Page 1
Forum section: electronics / projects

author: sagnikbasu
author_rank: Contributor
timestamp: May 09, 2017, 05:13:46 pm
content: Hi, I want to build a simple transceiver for power line communications. Is there any tutorial for it? Can it be done using an Arduino micro-controller?

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: May 09, 2017, 05:24:08 pm
content: Do you mean as X10, power line being the one that would kill you?

author: kripton2035
author_rank: Super Contributor
timestamp: May 09, 2017, 05:30:29 pm
content: buy some KQ130F module like this one :http://www.ebay.com/itm/252395992374it's cheap, tested, so you have less chances to get killed...some demo video here:
Power management for battery driven circuit - is this bad or good..? - Page 1
Forum section: electronics / projects

author: espena
author_rank: Contributor
timestamp: October 17, 2023, 04:14:27 pm
content: So, is this bad design, or am I onto something..? It would be nice to get some critical feedback.I'm sketching out a battery driven circuit using a WiFi module (ESP32 WROVER-E). See attached schematic, showing only the power management. I decided to go for 3xAAA lithium cells and a linear 3v3 LDO. Lithium because the circuit might draw more current than alkaline batteries can provide.With the energy level in Li cells i mind, I included a simple (perhaps too simple, omitting resistor and zener) reverse polarity protection (Q1) and a fuse.The power button is a tactile pushbutton (SW2), that sets a latch (the two schmitt triggers, U1), activating Q2, thus powering the circuit. The microcontroller then does it's thing, before driving IO33 high after a given battery saving timeout, which resets the latch, turning the power off. The standby current seems to be very low (a few hundred nanoamps in preliminary tests).Long pressing the power button should turn off the circuit immediately. The pushbutton is fed to IO36 on the controller. Since the button is connected directly to the battery (up to 5,5V), R16 and R5 reduces that voltage to a safe input level (below 3,5v, which is the specified maximum input voltage for the WROVER module).Am I on a viable path here? Found some online resources, but would certainly be glad to receive a couple of links outlining best practices
power measurement - Page 1
Forum section: electronics / projects

author: noobita
author_rank: Newbie
timestamp: January 19, 2016, 10:25:52 am
content: hello guyz! we are trying to measure a room's power consumption and we plan to use allegro current sensors.. can it measure properly currents from 100mA to maximum of 15 A?

author: Dave
author_rank: Super Contributor
timestamp: January 19, 2016, 04:11:03 pm
content: Depends on what your definition of properly is.

author: station240
author_rank: Unknown
timestamp: January 19, 2016, 08:09:23 pm
content: You need to look at the datasheets, see what sort of accuracy/error range it has. One current sensor I looked at is 1% accuracy, at 100A that means it's limited to 1A steps.For your example, I think 20A is the nearest size for Current Sensors anyway, so 200mA. See what you can find that is 0.5% or better (lower) accuracy.

author: dom0
author_rank: Super Contributor
timestamp: January 19, 2016, 08:17:12 pm
content: Quote from: station240 on January 19, 2016, 08:09:23 pm±1 % accuracy of full scale means that with 100 amps through the sensor it can read anywhere between 99 A and 101 A. Doesn't mean that theresolutionis 1 % (~2/log(2) ~7 bits).Accuracy is an interesting spec for mass production. For homebrew use one is normally more interested in drift (tempco, long-term) and linearity, because you can calibrate things easily manually to zero out errors.

author: noobita
author_rank: Newbie
timestamp: January 20, 2016, 03:31:35 am
content: TRIAD MAGNETICS CSE187L Current Sensing Transformer, someone suggested this one.. will it help me solve my problem?http://www.mouser.ph/ProductDetail/Triad-Magnetics/CSE186L/?qs=sGAEpiMZZMvHq2mgYB5gN1Bs7N%252bzhopi4eI8yg65QUA9r%252bby8sg4Zw%3d%3d

author: noobita
author_rank: Newbie
timestamp: January 21, 2016, 11:57:51 am
content: i'm not good at looking at/understanding Datasheets.i can replace those acs758s with current transformers right? all i want is to measure current from 100mA to 10A..
Power measurements for wireless arduino app - Page 1
Forum section: electronics / projects

author: bbt95762
author_rank: Contributor
timestamp: June 19, 2017, 04:42:12 pm
content: Hi Folks,I've developed a set of home temperature sensors, which are connected using wireless to a base station. I use rechargeable AA batteries to power the remote modules. They currently last about 2-4 months before needing a fresh set of charged batteries. I'd like to look at the current flow during the operations, preferably on my oscilloscope. Any ideas on cheap ways to do this? absolute accuracy is not critical - but *rough* accuracy.I'd hope to just look at the voltage drop from the unregulated battery - but I don't see any (guess that's good). maybe I'll need to go with a (cheap) shunt resistor.Thanks in advance,Brian.

author: Fungus
author_rank: Super Contributor
timestamp: June 19, 2017, 05:15:51 pm
content: 1 Ohm shunt resistor.I use these:http://www.ebay.com/itm/391795546037

author: bbt95762
author_rank: Contributor
timestamp: June 19, 2017, 06:29:30 pm
content: Thats a nice price - thanks!

author: Fungus
author_rank: Super Contributor
timestamp: June 19, 2017, 08:40:58 pm
content: One thing: A 1 Ohm resistor will be good for looking at spikes if there are any but your numbers suggest about 1mA average current. 1mA won't be very visible with a 1 Ohm resistor on an oscilloscope (depending on the 'scope).Youmightneed a 10 Ohm as well.I have10 Ohm,1 Ohmand0.1 Ohmin my arsenal.

author: bbt95762
author_rank: Contributor
timestamp: June 19, 2017, 11:20:31 pm
content: Thanks.My app puts the units to sleep for about 14 seconds, then wake up and work for 2 seconds, then sleep again - so the currents are a little higher.I used 3 10resistors in parallel - worked pretty well. Though when the transmitter power ups, it really draws current - and the voltage sank too much.Thanks for the help.
Power Meter Calibrator - Page 1
Forum section: electronics / projects

author: Phaedrus
author_rank: Frequent Contributor
timestamp: February 27, 2014, 11:09:16 pm
content: So we're getting a new power meter to use for our 1200W+ power supplies, since our current one tops out at 1400W AC. Problem is, the new one is less accurate and less time/temperature stable than our current meter. So I want a quick load I can use that is stable and accurate to calibrate with before doing serious measurements.So I've picked up some goodies:I got some 500 ohm, 50W, 1%, 20ppm/C power resistors, and a solid copper heatsink out of our scrap room.The resistors are 1% accurate, but in practice will likely be within +/-0.1%. I'll profile them with my multimeter to get the actual value. 20ppm/C, going from 25C to ~70C, gives me a resistance change of .45 ohms. At 120VAC that's a 0.025W difference per resistor. So this will be plenty stable for my needs.The heatsink is designed for server CPUs working in a low-airflow environment. It's solid copper and is designed to, without a fan, cool a 95W CPU to less than 75C. Using three resistors, I'll be around 85W, so I should be good. If it turns out they get too hot, I'll pop a fan on each side, which should keep it to below 50C.I'm going to drill into the copper and screw mount the resistors with some high quality thermal paste (we have a whole box of the stuff in the warehouse). Then attach the resistors in parallel with some stripped 14ga wire, solder it securely, then seal it with heat shrink. Attach the leads to a standard power cord, and plug into the meter for calibration.To calibrate the power meter I just need to plug it in, let it warm up for 10 minutes or so, then measure the AC voltage and the resistance of the calibration load, calculate the wattage, then plug that into the power meter. I should be able to get within <1% accuracy if I use the meter within the next couple hours, which is good enough for my usage scenario.Also the resistors are labeled "M1337", so clearly this makes me a pro h4ckzorz

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: February 28, 2014, 04:12:57 am
content: Hi,Testing with a resistor load will give you the accuracy of the power meter with a unity power factor load. You can measure the current with an ammeter and the voltage with a voltmeterpower = I x VDo you power supplies have a PFC and draw a nice sine wave current from the line, or are they non-PFC designs that draw a current with a modest crest factor?If the load is not unity power factorthen W is not equal to V x IPF = W / V x IJay_Diddy_B
Power mosfet gate current - Page 1
Forum section: electronics / projects

author: vignesh_shan
author_rank: Contributor
timestamp: November 18, 2020, 04:39:59 pm
content: Hi,Usually Gate of the mosfet is isolated by the SiO2 layer. Do the gate pin consumes current for its operation ?In high power mosfet devices how much current the gate can draw from the source ?Thanks,Vignesh.M

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 18, 2020, 05:13:45 pm
content: under static conditions there is not gate current; but depending on the gate capacitance there is a considerable current flowing in/out of the gate when switching the fet on/off

author: TimFox
author_rank: Super Contributor
timestamp: November 18, 2020, 05:23:13 pm
content: When considering the capacitive current at the gate terminal, remember to include the large contribution from the Miller effect of the gate-drain capacitance as the drain voltage swings.

author: rvalente
author_rank: Frequent Contributor
timestamp: November 19, 2020, 11:48:37 am
content: Take a look at International Rectifier App Notes (now infineon), pretty much everything you need to know about mosfets, igbts and gate drivers.Ixys/Fairchild/Fuji is a good knowledge source toooo

author: IDEngineer
author_rank: Super Contributor
timestamp: November 20, 2020, 08:43:04 am
content: The gate is a (complex) capacitor. Charging and discharging a capacitor involves current flow. The faster the charge and discharge, the higher the current for a shorter time. And you want to charge/discharge fast to minimize the time the FET spends in its "linear" region where dissipation is greatest.To give you an idea: I'm working with a small NFET right now and I'm charging/discharging its gate in ~40nS. This involves ~2 amps of peak current. So yes, there are real currents involved. Hopefully not for very long, but you must size your components and PCB traces accordingly. Your bypass caps too.

author: IDEngineer
author_rank: Super Contributor
timestamp: November 20, 2020, 09:17:16 am
content: I was thinking more about trace resistance. Gate resistors are generally small values so the "small" trace resistance can be a larger than normal percentage of the total.

author: IDEngineer
author_rank: Super Contributor
timestamp: November 20, 2020, 04:55:01 pm
content: Quote from: blueskull on November 20, 2020, 09:50:52 amHence my point about a larger percentage: That seemingly small 0.26R is nearly 7% of your 4R driver impedance. Gate resistors themselves are often single digit ohms. In my 2A 40nS example I'm using an 8.06R and considering even lower.EDIT: The "gate resistance" of the FET being driven must also be considered, as it too can be a significant percentage of the total impedances in the gate drive circuit. In my example the device has an Rg of 1.37R, which looms large relative to the values already mentioned.QuoteThat lower inductance helps reduce gate drive ringing, too. So sizing your PCB traces is important for quite a few reasons.
Power MOSFET switch over heating. Melting solder, - Page 1
Forum section: electronics / projects

author: guscrown
author_rank: Regular Contributor
timestamp: October 20, 2012, 05:17:35 am
content: Alright, continuing with the debugging of my new board tonight I found another issue worse than the one before: My switching MOSFET is getting so hot that I'm getting molten solder.I replaced the MOSFET with a short circuit just to see if the components sorounding the MOS were the cause of the problem (mostly a big Inductor I have right next to it) but the copper reaches a temperature of 110F, not enough to melt solder.This is my schematic:As you can see, my Vgs is around -11V and I'm running 3A through it using an Electronic Load. Based on the datasheet here:http://www.onsemi.com/pub_link/Collateral/NTD20P06L-D.PDFthis thing can do up to 15.5A.Any ideas of what might be going on?The only thing I could think of was that the heat on the copper could be increasing Rds(on) but at that particular low current it shouldn't be so serious.I am using the TO-252-3, DPak (2 Leads + Tab) package.

author: Rerouter
author_rank: Super Contributor
timestamp: October 20, 2012, 05:25:41 am
content: if you dont switch your mosfet very fast you it acts like a big resistor, that 100K is far too weak a pull up, configure a pnp-npn push-pull amplifier on the output of your op amp instead, you really need it moving quickly, to prevent all that heat as it slowly turns off,

author: guscrown
author_rank: Regular Contributor
timestamp: October 20, 2012, 06:06:29 am
content: I am not switching it. It is being used in steady state.

author: amyk
author_rank: Super Contributor
timestamp: October 20, 2012, 06:14:36 am
content: Then it's not switched on fully and still acting as a resistor. Measure the voltage drop across it.

author: SeanB
author_rank: Super Contributor
timestamp: October 20, 2012, 06:19:45 am
content: You need to be using a P type mosfet there as a high side switch. You will have a high voltage drop across it in this application, probably 6V or more
Power Multiplexer Circuit - Page 1
Forum section: electronics / projects

author: eerocketman
author_rank: Contributor
timestamp: April 21, 2018, 07:57:24 pm
content: Hi, I am working an amateur college rocket. Currently, while our rocket is on the ground we are loading and preparing the rocket I would like to power my system via an off board battery however when the rocket is in flight I'd like to use the on board battery. I was wondering if a simple relay circuit would work as attached. Am I over complicating this (will two diodes in series suffice?) or under complicating it? The off board power source will be a 24V go cart battery while the on board power source is 2 1000mAh 4S batteries in series. The system current draw is around 2 amps max.

author: ogden
author_rank: Super Contributor
timestamp: April 21, 2018, 08:43:57 pm
content: Quote from: eerocketman on April 21, 2018, 07:57:24 pmSo on-board around 32volts? Next time just tell voltage of both batteries so we don't have to guess chemistry and nominal charge %.Answer is: you can live with just two diodes, no relay needed.

author: Ian.M
author_rank: Super Contributor
timestamp: April 21, 2018, 09:11:50 pm
content: Nope. You cant use *JUST* diodes because the on-board battery would supply the power as the off-board battery is at a lower voltage.Also its desirable to minimise the weight of the circuit permanently attached to the rocket. If your system can tolerate 34V on its incoming DC bus, the optimum solution would be to use a 3A, 50V rated Schottky diode in series with the supply from the on-board battery + use a boost converter with the go-cart battery to get a regulated 34V, which would be applied after the Schottky diode, and would keep it reverse biased so there is no load on the on-board battery while powering your system. The boost converter's rectifier diode will prevent significant reverse conduction through it so you probably don't need an extra diode in series with its output. Without a relay, you wont get a momentary loss of power as it switches over from external to internal power, and the only extra weight on the rocket is the Schottky diode in series with the on-board battery + the external power connector (+ associated wiring), as the boost converter stays on the ground with the 24V battery.

author: ogden
author_rank: Super Contributor
timestamp: April 21, 2018, 10:48:22 pm
content: Quote from: Ian.M on April 21, 2018, 09:11:50 pmYes, you are right. I forgot to mention that external supply shall be same (or slightly higher) voltage. Kind of obvious.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 21, 2018, 11:11:04 pm
content: I have to admit I have never had the chance to work on a go cart, but 24V seems low. I'm under the impression they are generally 48V since that makes it easier to get a lot of power and still be within low voltage safety limits.

author: mikerj
author_rank: Super Contributor
timestamp: April 22, 2018, 10:12:10 am
content: Is an electromagnetic relay a good idea in something that would experience high levels of acceleration?
Power Muxing for USB and high voltage - Page 1
Forum section: electronics / projects

author: boguesuser
author_rank: Newbie
timestamp: September 11, 2024, 03:57:33 pm
content: I am working on an ESP32 dev board. I want to power the board via either USB or 30v connector.How does one typically prevent the 30v from going to the USB if both connectors are connected at the same time?

author: ledtester
author_rank: Super Contributor
timestamp: September 11, 2024, 04:14:20 pm
content: You could get some ideas from this design:https://oshwlab.com/Miraculix200/esp32-s3-mini_copyThe diode D1 will protect the USB +5V rail. The external power, if applied, should always be at least 5V.For the scenario where the external power is a lower voltage battery and you want to have the battery charged when USB is applied, have a look at the schematics for the Adafruit ESP32 Feather:https://learn.adafruit.com/assets/110822

author: boguesuser
author_rank: Newbie
timestamp: September 11, 2024, 10:33:19 pm
content: I'm just a bit slow.Is a schottky diode all that's needed to protect the USB device?And is a schottky used here due to lower forward voltage drop?

author: ledtester
author_rank: Super Contributor
timestamp: September 11, 2024, 10:57:43 pm
content: Another diode could possible work depending on the headroom required by the 3.3V regulator. The current the MCU needs could also be a factor.

author: boguesuser
author_rank: Newbie
timestamp: September 12, 2024, 02:01:37 am
content: Ok. Thank you for your help.I'd at most be pulling 3.3 watts and can tolerate 4.2v of input voltage to the regulator.

author: Salitronic
author_rank: Contributor
timestamp: September 12, 2024, 08:30:29 am
content: Quote from: boguesuser on September 12, 2024, 02:01:37 amIf you are expecting to draw 3.3W (I'm assuming this is on the 3.3V) through an LDO, that translates to30W on the 30V input, with over 26W wasted in the LDO.You need to use a buck converter.
Power-OFF Transient.......  Do you think this will do any long term damage? - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: December 26, 2017, 05:17:16 pm
content: I have a low current 5.4V power supply based on the LM5008. It works fine on power-up and when running, however on power down there is a fairly nasty looking burst that lasts about 1.5ms (see image below).My concern is that one of the IC's in the circuit is rated 6.5V absolute max for Vcc, and it will see perhaps 50 short duration spikes 100ns long in the 6.5V to 10V range during the 1.5ms power-down period. This is a penny pincher design so I would prefer to not add an additional clamping device if reliability is unlikely to be effected. FWIW, the device will normally run 24/7 not constantly be powered up and down.Thoughts?If a clamp should be added, what would be best; Zener, TVS, MOV?

author: jmelson
author_rank: Super Contributor
timestamp: December 26, 2017, 05:56:38 pm
content: Don't believe everything you see on a scope. Clip the probe's ground clip to the equipment ground, then clip the probe's signal contact to ground also, and turn the power off. I'll be you see a similar burst of noise. This is induced noise due to the power switch sparking at turnoff.if this transient exists at all (and I doubt it) it is likely much less than your measured result. It may be possible to get a more exact reading with two probes. Put probe 1 on the power supply, put probe 2 on the ground (and all ground clips to ground). Then, set the scope to subtract channel 2 from channel 1 and see what you get.Jon

author: Jester
author_rank: Frequent Contributor
timestamp: December 26, 2017, 06:11:11 pm
content: Quote from: jmelson on December 26, 2017, 05:56:38 pmJon, thanks for the quick response. I connected another probe (blue) see below. The duration of the burst varies (likely based on where in the cycle the power is turned off), this one is shorter.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: December 26, 2017, 06:13:38 pm
content: Probe 2 has a bandwidth limiter enabled - turn that off and re-run.

author: Jester
author_rank: Frequent Contributor
timestamp: December 26, 2017, 06:25:49 pm
content: Quote from: radar_macgyver on December 26, 2017, 06:13:38 pmThanks, I missed that. Yes indeed it looks much better.

author: jaycee
author_rank: Regular Contributor
timestamp: December 27, 2017, 02:31:13 am
content: Fit a 100nF X2 rated film capacitor across the switch contacts. That will likely kill a lot of the noise.edit: you can also get "contact suppressor" devices which are effectively an RC snubber network. Those should work as well.
Power-on surge control - Page 1
Forum section: electronics / projects

author: Messtechniker
author_rank: Frequent Contributor
timestamp: December 11, 2017, 07:09:57 am
content: With so many switching power supplies* in the lab, switching these all on at once caused tripping of the automatic circuit breaker ever so often. Solved the problem by fitting a power-on surge limiter – see pic – downsteam of the main switch. Mine is an EBN 2 made by Schalk for hat rails. Works.* 3 PCs, 3 screens, scope, lab power supply, DMM, network switch and several 12 V wall warts
Power One power supply - Page 1
Forum section: electronics / projects

author: bob91343
author_rank: Super Contributor
timestamp: December 28, 2021, 10:26:18 pm
content: I was recently gifted an old power supply, Power One model HE 15-9. It's rated for 15V out at 9A.If anyone has a schematic or manual for this I would appreciate getting the information. Google has not produced anything useful. It seems the company was bought out a few years ago and there is no useful website.

author: duak
author_rank: Super Contributor
timestamp: December 29, 2021, 12:33:02 am
content: I've never seen schematics published by the manufacturer. However, here's a website that is very useful:https://www.djerickson.com/p1hack/

author: bob91343
author_rank: Super Contributor
timestamp: December 29, 2021, 01:45:55 am
content: Thanks for that, duak! I discovered that my 15V supply could be adjusted to the desired 13.8V by the little cheap pot they used. That makes the 9A rating a bit optimistic so I best stay well below that.I never looked to see if there is a 723 in there but I will.The company seems to have disappeared, for all practical purposes. Mine came with a hard wired power cord but no fuse or switch, an omission easily corrected.

author: ledtester
author_rank: Super Contributor
timestamp: December 29, 2021, 03:01:47 am
content: Looks like Power One was acquired by Bel Fuse:https://ir.belfuse.com/news-releases/news-release-details/bel-closes-acquisition-abb-power-one-solutionsAlso:https://www.artisantg.com/TestMeasurement/71753-9/Bel-Fuse-Power-One-HBB15-1-5-A-Power-Supply

author: bob91343
author_rank: Super Contributor
timestamp: December 29, 2021, 03:35:01 am
content: Well yes there is a 723 in the unit, the 14 pin DIP style.As for the acquisition information, well the balloon doesn't seem to have been inflated very much, as Power One's existence is a bit dubious. Be that as it may, the supply I have works okay (although I haven't put a load on it yet).But it was free so I have no complaints.
Power OR-ing Circuit Design Challenges: MOSFET SOA and Fast Switching - Page 1
Forum section: electronics / projects

author: OwenH
author_rank: Contributor
timestamp: December 18, 2024, 01:45:25 pm
content: Hi everyone,I’ve been working on a power OR-ing circuit for a project, and I’ve hit a few design challenges I hope to get some input on.The circuit is a power OR-ing controller designed to switch between an external battery and a power connector. Both inputs operate between 10-18V DC and can deliver up to 20A. The design has overcurrent and overvoltage protection at both inputs.I selected the TI LM74900 ideal diode controller for this application. It features back-to-back MOSFET control for OR-ing and integrated current sensing for overcurrent and short-circuit protection. My circuit design follows the TI reference shown in one of their Ti design journals (attached).Here are my key concerns:Staying within MOSFET SOA: I need to make sure that my MOSFETs remain within their Safe Operating Area (SOA) during startup and transitions.Fast Switching: The circuit must switch sources quickly to minimize voltage dips at the output. Power source transitions could happen frequently (every 10-20min), as either the battery or power cable may disconnect at any time.Startup from Either Source: The device should be capable of starting from either power source and switching between them dynamically.The LM74900’s low current drive on the Q2 gate limits inrush current but slows down the response time. To address this, I’ve followed the TI application note to add a transistor on the Q2 gate, increasing the gate drive current. However, this modification means I can’t use TI’s calculator tool to verify if Q2 stays within its SOA during startup. There is about 300uf of capacitance but no real resistive load on the output.For the MOSFETs, I’m considering the Infineon IAUCN04S7L004 due to its very low RDS(on), my board is compact so I'm trying to reduce the thermal impact.Questions:How can I ensure fast switching while staying within the MOSFET SOA during startup and transitions?Are there alternative approaches or controllers that could simplify the design without compromising performance?What is a typical response time for an OR-ing circuit like this, and would omitting the Q2 transistor (and its associated drive circuit) be an option?I’ve attached the TI schematic for reference. Any advice or insights would be greatly appreciated!Thanks!Owen
Power over DVI connector? - Page 1
Forum section: electronics / projects

author: Mamybopo
author_rank: Newbie
timestamp: April 20, 2018, 05:56:18 pm
content: I found this old 7" 800x640 touchscreen panel from a Konica business printer. It has a DVI-D connector, but that is the only connector on it. No power!The DVI standard has 5V 50mA on pin 14, which seems much too little to drive even a small TFT screen.Inside the device, there's a switching PSU board with a 125V 1.5A fuse, among other things.I'm afraid to plug this monitor to my graphics card to test, because I suspect that Konica simply used the DVI connector because it was a cheap and available 24 pin cable.What is the easiest way to determine if it is safe to connect this to a regular DVI output and perhaps supply 5V externally?

author: iwtommo
author_rank: Contributor
timestamp: April 20, 2018, 06:34:08 pm
content: Follow the traces from the fuse to wherever they go?Surely a dvi connector doesnt send 125v at 1.5a

author: Yansi
author_rank: Super Contributor
timestamp: April 20, 2018, 07:42:44 pm
content: The DVI connector on this display is nowhere close to a DVI signal standard, as far as I remember forum thread from some years back.DO NOT plug to the PC graphics card!

author: Mamybopo
author_rank: Newbie
timestamp: April 21, 2018, 05:11:56 pm
content: Was that an eevblog forum thread?

author: Yansi
author_rank: Super Contributor
timestamp: April 22, 2018, 09:28:35 am
content: I am not sure, unfortunately. But I recall well a discussion about a display panel from a printer, with a DVI connector, that was nowhere near the DVI connector.But that should be absolutely clear to anyone, who knows a bit about DVI, that you can't supply a 7" LCD panel from the integrated 5V DDC power, and that there is no way in hell to manage a touch screen with it.Just open the sucker, I recall that there was also Texas Instruments flatlink receiver chip, like a SN65LVDS86A. (So no TMDS signalling either, good old LVDS instead).Should be easy enough to interface, if you work out the connector pinout.
Power path (load sharing) 3 sources - Page 1
Forum section: electronics / projects

author: okw
author_rank: Frequent Contributor
timestamp: March 29, 2023, 05:37:32 pm
content: I'm designing a a circuit for power path (load sharing) which takes 6V DC adapter or USB to power a TP4056 Li-Ion charger, which in turn charges a battery. If only battery is present (no DC in / USB), this should power the 3.3V regulator which supplies the rest of the load. If USB is present, it should charge the battery and at the same time power the 3.3V regulator (not draw from battery). If DC is present, it should do the same as USB, but "disconnect" USB, so I'm not pumping 6V into the USB rail.Would the attached circuit be sufficient? Or could this be done more elegant?I didn't utilize the "ground breaker" (when plugged in) in the DC socket. Maybe using this could save me a component or two, or make the circuit better?Also not sure if I need the diode on the DC input?Note, all TP4056 circuitry is left out for readability.
Power Path design review - Page 1
Forum section: electronics / projects

author: Sariel
author_rank: Regular Contributor
timestamp: November 15, 2024, 08:42:44 am
content: Hello,I’m designing the power path for my upcoming open hardware project: a precision measurement amplifier focused on DC/AC current, voltage, power, energy, and charge.This power path is solely responsible for generating the internal supply voltages, yet it already accounts for 50% of the BOM and is proving more complex than anticipated. SEPIC converters and USB Type-C PD controllers bring significant complexity.The plan is to create ±18.5V for current-sense amplifiers, enabling current measurements on common input voltages up to 16V, as well as 5V for the MCU and ADC to sample currents and calculate energy, power, and charge. The readings will be displayed on monochrome OLED screens.What do you think of this design so far? Is there anything I might be overlooking? What potential pitfalls should I watch out for? Should I prototype just this section to test it in the lab before diving into the analog/digital design?Feel free to provide honest and direct/harsh feedback.I thrive on negative feedback, it keeps me stable.DC_Power_Meter.pdf(766.77 kB - downloaded 46 times.)

author: Andy Chee
author_rank: Super Contributor
timestamp: November 15, 2024, 09:22:01 am
content: Don't triple posthttps://www.eevblog.com/forum/projects/precision-measurement-of-current-voltage-energy-charge-and-power-open-source/msg5701087/#msg5701087
Power plane thermal relief - Page 1
Forum section: electronics / projects

author: kaadam
author_rank: Contributor
timestamp: August 02, 2015, 06:58:44 pm
content: Hi!I currently working on a 4 layer PCB. One of the reviewers said i should disable thermal reliefs, because with the reliefs "the plane makes no sense". I don't want to disable it, becouse we going to solder it by hand. Whats your opinion about that? Can a thermal relief lead to perfromace issue?Thanks a lot!

author: MagicSmoker
author_rank: Super Contributor
timestamp: August 02, 2015, 07:05:59 pm
content: Quote from: kaadam on August 02, 2015, 06:58:44 pmYeah, you don't want to use thermal reliefs for a component that needs to dissipate significant power (where "significant" for SMT might be 0.25W), but as you have already guessed, without thermal reliefs it will be difficult to hand-solder UNLESS you use hot air, which you should be doing anyway for hand assembly of SMT components.

author: kaadam
author_rank: Contributor
timestamp: August 02, 2015, 07:16:41 pm
content: Sorry, i posted it twice beacouse of my bad internet connection.Thanks! There is no significant power dissipation, we talking about STM32F407. Only one LDO can dissipate much, but it has his own thermal pad and it is well connected to the whole GND plane with 12 vias. Under performance issue i rather mean parasite components, inductance, etc.

author: nctnico
author_rank: Super Contributor
timestamp: August 02, 2015, 07:32:58 pm
content: Don't disable thermal reliefs on throughhole pins. Hand soldering will be a nightmare. I only disable the thermal reliefs for vias which transfer heat or when a pin carries a lot of current.

author: MagicSmoker
author_rank: Super Contributor
timestamp: August 02, 2015, 07:38:15 pm
content: Quote from: kaadam on August 02, 2015, 07:16:41 pmAre you asking if putting thermal reliefs on the 12 *vias* in the ground pad for a garden variety ARM processor will affect signal integrity? No, they won't. They won't help much with soldering, either, though. For a largish QFP package with exposed pad you kind of need to do the soldering with a reflow oven.
power rail for DAC - PCB layout - Page 1
Forum section: electronics / projects

author: kamtar
author_rank: Regular Contributor
timestamp: March 06, 2020, 11:13:26 am
content: Hello,I'm trying as my hobby project to design USB DAC so far I'm okay with my PCB layout except for one thing and that is 3V3 rail for CS4398.As you can see in an attached picture it's going all around PCB.1. Should I be worried about it? Not sure how digital power rail is important for DAC.2. If yes what would be the best solution, to break my ground plane more and route it directly, or maybe to put another LDO next to the IC?

author: Evan.Cornell
author_rank: Regular Contributor
timestamp: March 06, 2020, 07:30:55 pm
content: 4 layer PCB, Layer 1 signal, Layer 2 ground, Layer 3 power, Layer 4 signal. 4 layer boards are not that expensive.

author: kamtar
author_rank: Regular Contributor
timestamp: March 06, 2020, 10:39:23 pm
content: This will be 2 layers only. If I would use 4 layer cost would go from 20 USD to 100USD, that's not in my budget for PCB.

author: David Hess
author_rank: Super Contributor
timestamp: March 07, 2020, 12:52:40 am
content: It will be fine as long as high frequency decoupling requirements are met.
Power Resistor Characterization - Page 1
Forum section: electronics / projects

author: mawyatt
author_rank: Super Contributor
timestamp: July 02, 2024, 05:18:24 pm
content: Need to characterize some power resistors for higher speed applications than the usual audio frequency range. The Dale RH-10 10 Watt chassis mount type power resistors are what we've selected, and have served us well in the past; stable, rugged and reliable.Normally to characterize these we would use some quality Kelvin Clips with our DMMs or LCR meters, however we need to check the resistor behavior up to ~1MHz and some cases ~5MHz. The Kelvin Clips we have aren't specified above 100KHz, which leaves the usual approach with a custom fixture (calibration), and maybe even for VNA use.Then remembered {don't laugh, this is getting harder and harder} some time ago we purchased some B&K fixtures (TL89F1 and TL89K1*) for our bench LCR meters, one of which has additional "adapter inserts" for leaded components V & H orientation.Turns out these adapter inserts (TL89F1) have just enough spacing to allow the Dale RH-10 Power resistors to be inserted as shown. This fixture can be "zero/short calibrated" with the standard metal short for the normal leaded fixture use if the short is flipped over and inserted with the curved end which provides an excellent "zero/short" over the full range of our IM3536 (8MHz).Now what was heading to be a PITA turns out to be a simple easy, accurate and repeatable measurement* The B&K TL89K1 is the Kelvin Clips for BNC use with LCR meters and is a rebrand of the Tonghui TH26011CS, the TL89F1 is a fixture for leaded components (adapters for Horizontal or Vertical lead insertion) for direct mount to the LCR meter and from unknown OEM.Best,

author: exmadscientist
author_rank: Frequent Contributor
timestamp: July 03, 2024, 12:46:41 am
content: NiceAs a tangent, around here we had some trouble with poor construction on those Dale aluminum housing chassis resistors. The cores were falling outWe could have tried to fix them up, either unit by unit or with Vishay Dale (who have obviously been tampering with the ancient, proven design....) but we did the lazy thing and bought another brand. TE HSC parts are really nice! Not that we needed MHz out of them....

author: mawyatt
author_rank: Super Contributor
timestamp: July 03, 2024, 12:55:37 am
content: That's sad to know that Vishay has messed up these Dale resistors. We never had issues with them in the past, now concerned for use in newer designs!!Thanks for noteBest,
Power selector switch IC and short circuit protection - Page 1
Forum section: electronics / projects

author: VEGETA
author_rank: Super Contributor
timestamp: October 24, 2024, 09:44:57 am
content: Hello,I have a PSU design that is working fine. it is 3.3v and 5v output usingtps564247regulator. expected current consumption is 2-2.5 amps max on 5v and less than 1 amp for 3.3v. the switcher has internal short circuit protection and TI support ensured that it is protected perfectly fine.however, i do have a selection switch or circuit to select between 3.3v and 5v on a certain output pin, while the other pin has 5v all the time.the switch ic selected wastps2117rated at 4 amps. however as ti support mentioned, it does not have short circuit protection while the switcher is rated at 4 amps but it can go more like 5-6 amps before short circuit or over current protection kicks in which may do damage to tps2117.the selector switch used is a low power slide switch which is used on the tps2117 selection pin.thinking of all of this + insisting on getting a real secured short circuit protection on the device I thought of the following:Option 1:keep the circuit as is, thus rely on buck regulator reliable ovp to kick in before any damage happens to tps2117 assuming all faults will be quick and no prolonged currents over 4 amps. realistically this should be ok since the device will not get 3.3v more than 1 amps or even less.Option 2:remove tps2117 and all of its circuit, and replace it with a simple powerful rocker switch like this:https://www.digikey.com/en/products/detail/e-switch/RR113C1100/2116253this way, the 3.3v rail will be internally short circuit protected by the buck itself (a bit above 6 amps) which means no harm can ever be done. this rocker switch costs around 1$ from digikey while option 1 costs the same from LCSC, price won't be an issue. the switch being ON-ON type is what I want + no marking.what do you recommend I do??I know option 2 is the best but I already got the prototype which I hoped it will be the final one, now I will wait another 1.5 months to get another one which is a delay... or should I just go to production with option 2 without making a prototype for it first, knowing how easy and fault-free it can be?for your kind help and advice.thanks!

author: VEGETA
author_rank: Super Contributor
timestamp: October 25, 2024, 12:35:42 am
content: if i want to keep the current design, i was advised by TI to put an eFuse before this IC.TPS25925 family seems promising, where I can set it via resistor 100k to be around 3.7 amps which is noticeably less than 4 amps current limit of the switching ic.this is for 3.3v since it can only go to output pin via tps2117.however, i don't think i need it for 5v since even if user picked 5v, it will be delivered to 2 pins... first pin is the all-time hard wired 5v and the other is the switched 3.3v\5v. thus I assumed the maximum 6 amps buck can deliver before its own ocp.... it will be 3 amps for each pin (slightly less for the switched one since r_on).do you think it is a good idea?or getting that beafy switch is the better way?
Power sequencing - chip powered via it's IO - Page 1
Forum section: electronics / projects

author: Pat Pending
author_rank: Regular Contributor
timestamp: April 13, 2019, 06:57:27 pm
content: HiI have two connected chips (master/slave), both powered at 3v3.When power is removed from the slave it's supply rail shows 1.9V - the outputs from the master back feed power into the slave.The difference is 1.4V. One diode should be the protection diode on the IO and would account for 0.7V but I can't explain where the other diode drop (i assume) would be.I Googled but still looking for a good explanation.Thanks

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 13, 2019, 07:33:27 pm
content: Some 3V3 microcontrollers have an internal voltage regulator and work with a lower core voltage.There may also be some modified internal structures to make pins compatible with 5V logic.I wouls also not assume it's only ESD diodes, nor that the voltage drop over an ESD diode is 600mV.