hybridfree/eevblog-posts huggingface dataset:
Power electronics snubber circuits. - Page 1
Forum section: electronics / beginners

author: Kemme
author_rank: Contributor
timestamp: October 14, 2016, 04:53:22 pm
content: Hello allI had an opportunity to examine high power voltage source inverter and I found out that there is a snubber circuit in the rectifier section. The snubber consists of a capacitor and resistor across the DC+ and DC- outputs of the rectifier so I assume that they are just dV/dt limiters. But, are they really needed? I know that it is sometimes essential to design snubber circuits on the inverter side to minimize the voltage overshoots and current rise times during the switching but I have absolutely no idea why are they needed on the rectifier side.

author: SeanB
author_rank: Super Contributor
timestamp: October 14, 2016, 05:53:07 pm
content: The rectifiers create a change in current as they turn on or off, and with the unknown line and load inductance this can make for a large voltage spike, especially if you have the line reactor installed to increase the input impedance on a low impedance supply.If you have a very low impedance supply ( typical in an industrial environment, where you could literally have a supply impedance in the low milliohm range) the turn on spikes can be very large, definitely enough to damage the junctions from overvoltage or from concentrating the current in a small spot on the die as the slow portions of the diode turn on or off. If you look at the datasheets for all inverters you see the need to increase supply impedance in certain conditions with a line reactor.
power electronics - Page 1
Forum section: electronics / beginners

author: Balaji
author_rank: Newbie
timestamp: February 20, 2017, 09:18:57 am
content: We need to convert M831 Electronic YZC 131 5kg weighing weight scale pressure sensor load cell output to voltage. So that we can convert the voltage output to 4 - 20milliamps to give input to the PLC. Is there any circuit directly convert millivolt to milliamps?

author: Delta
author_rank: Super Contributor
timestamp: February 20, 2017, 09:26:54 am
content: Why is this a poll, and what has it got to do with power electronics?Google "loadcell amplifier".
Power ESP32 from the Vin pin and the USB at once - Page 1
Forum section: electronics / beginners

author: Rapidice
author_rank: Newbie
timestamp: February 28, 2021, 01:05:53 pm
content: Hi, I have been using an ESP32 for my project, in which I am trying to power the ESP with a boost converter set to 6v. Now, I have a problem, where I can not use the USB ( connect it to my pc for programming ), without turning off the boost converter first. The USB power is (I think) directly connected to the Vin pin. Is there a chip/circuit I could use to automatically turn off the power from the boost converter or just to make sure the boost converter doesn't interfere with the USB power?This is the ESP I use:https://www.aliexpress.com/item/4000992721907.html?spm=a2g0o.productlist.0.0.36ac3390NQen02&algo_pvid=fd7a531f-360c-4598-819a-ff7d79c4e3a9&algo_expid=fd7a531f-360c-4598-819a-ff7d79c4e3a9-2&btsid=0b0a119a16144557539773819ee991&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

author: mvs
author_rank: Frequent Contributor
timestamp: February 28, 2021, 06:57:18 pm
content: USB power and Vin pin are separated throught diode, which is important for safe operation.This board should be based on following schematic:https://dl.espressif.com/dl/schematics/ESP32-Core-Board-V2_sch.pdfFor proper operation VBUS pin of CP2102 should get power only when it is connected to USB. Espressif has connected it to Vin (EXT_5V net on schematic) and it looks like this is a root of your problem.You can try to supply your board with 3.3V throught 3.3V pin to solve this issue.
Power Factor - Page 1
Forum section: electronics / beginners

author: SamwelP
author_rank: Newbie
timestamp: May 23, 2019, 06:12:55 pm
content: Hello guys, what are the benefits and disadvantages of having a leading power factor and why ?

author: helius
author_rank: Super Contributor
timestamp: May 23, 2019, 06:30:04 pm
content: Leading power factor compensates/cancels a lagging power factor. This is called power factor correction (PFC).When either leading or lagging PF is not compensated, it causes circulating currents to flow in the supply wiring, which increases thermal loss and can cause other problems. Utilities may charge higher rates because it increases the load on their distribution network.

author: Benta
author_rank: Super Contributor
timestamp: May 23, 2019, 07:01:41 pm
content: Question is too unspecific to provide a sane answer.

author: MosherIV
author_rank: Super Contributor
timestamp: May 23, 2019, 08:48:25 pm
content: QuoteThe question is the wrong way round. There is no advantage, there is disadvantage to positive or negative PF.Helius has tried to explain this.I like to explain it like this:AC has changing voltage. At some point the voltage crosses 0V.It takes voltage to 'push' current through circuits.When the Voltage is at 0V, there is no voltage ('presure') to push current through the circuit.So if you have a circuit that requires current at the 0V point, it becomes very difficult to get current to flow.This is the reason utility compannies charge more when you are out of phase.PFC is to re-align your power draw to the AC waveform.Hope that helps

author: David Hess
author_rank: Super Contributor
timestamp: May 24, 2019, 02:05:34 am
content: Quote from: helius on May 23, 2019, 06:30:04 pmJust to be clear here, the circulating currents still exist but only between the load and the point where the power factor correction is applied which removes the circulating currents from the long transmission lines.
power factor - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: February 27, 2018, 01:31:37 pm
content: Hi, I have a doubt I can make this connection on an oscilloscope, to see the intensity and voltage and calculate the potential, since I do not have an ampirometric clamp, the doubt is for the common raisins that my oscilloscope has

author: BrianHG
author_rank: Super Contributor
timestamp: February 27, 2018, 11:34:45 pm
content: So long as your transformer is a real linear transformer isolated from the mains, and there is no connection to earth GND anywhere in your illustrated connection, that exact circuit is safe.If your power supply is a switching transformer which may have one of the source wires connected to earth GND, just like the GND pin on your scope's power plug, which makes connection to the GND on the scope probes, then you may potentially be sending +/-12v, thus high current into the GND clips of your scope.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: February 28, 2018, 12:13:29 am
content: thanks for the answer, if both the transformer and the oscilloscope have no connection to ground. (GND)

author: BrianHG
author_rank: Super Contributor
timestamp: February 28, 2018, 12:41:14 am
content: Quote from: Adrian_Arg. on February 28, 2018, 12:13:29 amYour scope always has a connection to GND and you should always consider that to be true if you don't have a battery powered scope. It's only because the transformer in your illustrated circuit is isolated from the mains power that you can safely probe the circuit the way you illustrated.

author: David Hess
author_rank: Super Contributor
timestamp: February 28, 2018, 01:40:01 am
content: That will work fine and is often done to use an oscilloscope as a quick curve tracer. Place the ground clips close together.

author: besauk
author_rank: Contributor
timestamp: February 28, 2018, 03:41:19 am
content: Also, you would typically invert one of the channels to see a consistent 2 terminal I-V characteristic.
power failure backup circuit - Page 1
Forum section: electronics / beginners

author: daryldee
author_rank: Newbie
timestamp: June 10, 2016, 08:03:45 pm
content: Hi all!I'm designing a board with an atmel MCU (atxmega32e5) that drives an oled, 4 high power LEDs with its relative buck drivers and all the frills that a little device needs.What I would accomplish is to have a power failure advice/trigger when the main power is lost to actuate trough an ISR call an NVM write and save all the configs of this device.I did not calculate already the NVM data write timing, but I guess we're talking about few mS.So, the circuit I'm missing is a method to keep the power to the MCU alive for enough time.The circuit runs with 3 different power rails:- 3.3v (MCU and OLED)- 5v (rs232 driver)- Main 12/18v (led driving stage)As of my knowledge, the best way would be to go analog and keeping energy storage up enough to allow the NVM write cycle.What I miss, is a method to separate power domains and avoid that simple capacitors will discharge with the rest of the circuit.what would you do?Thanks!D.
Power for logic part - Page 1
Forum section: electronics / beginners

author: grbolet
author_rank: Newbie
timestamp: August 08, 2012, 01:02:40 pm
content: Hi,I have project which is primarily powered from 24VAC wall adapter, then rectified and smoothed so I get around 33V DC.I need to power some logic ICs (MCU, memory, LED pwm driver, ...) with 3.3V drawing up to 120mA.I want to keep size small (preferably use the SMD components) and also cold as possible, so linear regulator is probably not best solution, as it will dissipate more than 3W of power.And DC-DC converters capable of input larger than 30V seems to be pricey (>5 $/unit, at least on regular distributor), altough one can buy assembled dc-dc module on ebay for less than 2 $ including shipping.Is there any other way ? Or some "secret" tweak of one of upper two ways?Regards

author: Psi
author_rank: Super Contributor
timestamp: August 08, 2012, 01:36:19 pm
content: *Assuming you don't actually need the 33V for anything you can swap the full-bridge for a half-bridge to reduce the voltage down to around 16V.(To compensate for the missing cycles you will need to increase the size of the capacitor.)* The transformer may have a center-tap you could use, however that would require 3 wires from the wall adapter.* If your 33V is just a bit too high for some dcdc modules you might consider a string of diodes in series to drop the voltage a little.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: August 08, 2012, 01:46:01 pm
content: Simpleswitcher IC + few parts.Still more expensive than linear regulator, but keep in mind that 3W of power waste requires a fair bit of heatsinking too, so linear is also more expensive than just the bare LM317 or similar.

author: grbolet
author_rank: Newbie
timestamp: August 08, 2012, 02:09:51 pm
content: Actually 33V are powering LED strings connected to LED driver.

author: mariush
author_rank: Super Contributor
timestamp: August 09, 2012, 01:40:41 am
content: http://www.digikey.com/product-detail/en/LM2574N-3.3G/LM2574N-3.3GOS-ND/1476674in 4.75 V ~ 40 Vout 3.3v 500mA fixedLooks pretty straight forward.

author: grbolet
author_rank: Newbie
timestamp: August 09, 2012, 08:37:54 am
content: I finally came to same dc dc converter (Simpleswitcher was perfect lead).Thanks to all
Power from trace vs copper pour - Page 1
Forum section: electronics / beginners

author: newtekuser
author_rank: Frequent Contributor
timestamp: February 03, 2024, 08:00:50 pm
content: Let's say in my schematic I have a capacitor connected to a power pin, the simplest way I know how to route the connection between the two is by connecting a trace between the positive terminal of the cap to the positive terminal of the power pin, and negative terminals using vias to the ground plane.Lately I've gotten "fancier" using copper pours connected to the power net, so now I'm simply dropping the fooptrint of the capacitor onto the copper pour and connect the ground pin to the ground plane using a via. I no longer have to connect the positive terminal of any components placed on this copper pour because they are all connected to power.If now I place components on copper pours like in the example above, I can place them wherever I desire as long as they are on the copper pour and connect to the correct net. As a newbie, this raises some questions:1. If I have components that need to connect with others in parallel or series, how does placing them on a copper pours without traces affect their connections? (I think my problem is that I'm visualizing them as they are connected in the schematic)2. Also, what happens if I place this capacitor farther away from the power pin? (let's say the cap now sits physically behind another component)I do have designs using copper pours that just work but I'm questioning how it is possible.Hope my question makes sense.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: February 03, 2024, 08:54:01 pm
content: If your pour isn't solid and is full of slots, you will have noise problems.

author: Clear as mud
author_rank: Regular Contributor
timestamp: February 04, 2024, 05:07:52 am
content: Components are still in parallel, whether or not the schematic "wires" are really traces or pours.Distance from capacitor makes a difference, impedance goes up at high frequencies. If a digital output suddenly turns on, and the capacitor is halfway across the board, the rise time will be much longer. Such effects could cause glitches if voltages change enough to be LOW instead of HIGH or vice-versa.

author: newtekuser
author_rank: Frequent Contributor
timestamp: February 04, 2024, 06:19:04 am
content: Quote from: Clear as mud on February 04, 2024, 05:07:52 amExcellent, thanks a bunch!!
Power getting to COB LED chip, but no light - Page 1
Forum section: electronics / beginners

author: Ilsignororso
author_rank: Newbie
timestamp: July 20, 2020, 06:40:40 pm
content: Hi everyone,I ran into a little problem with my project to build a cherry tomato nursery. While I had a number of successful Arduino projects, I am relatively new to these types of electronics tasks.For a start, I chose two COB LED units, 50W each (Attached to heatsinks with a thermogel layer in between). I also have a driver unit, capable of supplying 150W at 12V - the same voltage that's required by the LED chips. After some effort in soldering and wiring, I put everything together. When I plug in the driver, I measured the desired 12.35V with a multimeter leaving the PSU, I have the 12.35V arriving to the other ends of the wires that are soldered to the chips (I checked, to the right polarity), and yet, there is not a drop of light coming out of the setup.Here is a picture of what I have:The driver is an OPTONICA AC6114The LEDs are 25x25mm, 12V, 50W chips.I would really appreciate some help, if you have some tips on how I should approach this problem. Thanks in advance!

author: tooki
author_rank: Super Contributor
timestamp: July 20, 2020, 08:33:59 pm
content: Those black cube things on the LED modules — and the high voltage symbol (lightning bolt in warning triangle) — strongly suggest those are not 12V LED modules, but rather mains AC ones intended for 120V or 230V. 12V COB LED modules normally don’t have any visible components on them beside the LED chips themselves.Check your order to make sure you didn’t order 120V ones by mistake. If you’ve verified your order says 12V, then talk to the seller.
Power Good Open Drain, can I leave it floating? - Page 1
Forum section: electronics / beginners

author: alexg
author_rank: Regular Contributor
timestamp: December 28, 2016, 11:54:33 pm
content: Hi All, I built circuit base don TPS63060 regulator to play with, here is the datasheet:http://www.ti.com/lit/ds/symlink/tps63060.pdfThere is a PG (Power Good) pin that datasheet says is an open drain, I do not use power good feature so to spare a tiny bit of board space and to save one resistor I am thin king to leave it floating, is that a good idea? Maybe I can also just connect it to the PGND pad under the chip? Is that okay?

author: danadak
author_rank: Super Contributor
timestamp: December 29, 2016, 02:05:42 am
content: Either way, leave open or grounded. Grounded might lessen leakage thrudrain connection, which is wasted power.Regards, Dana.

author: alexg
author_rank: Regular Contributor
timestamp: December 29, 2016, 03:06:15 pm
content: Thanks, I will connect it to the ground then. How much leakage are we talking about it is in mA, uA or nA?

author: danadak
author_rank: Super Contributor
timestamp: December 30, 2016, 11:15:57 am
content: Leakage specs are in the datasheet. Typically nA, but datasheet normallyin the single digit uA area for worst case.Regards, Dana.
Power inductors projects to explore - Page 1
Forum section: electronics / beginners

author: VSV_electron
author_rank: Regular Contributor
timestamp: March 09, 2023, 10:03:46 pm
content: Hello!While stocking common components not long ago I got myself a so-called "power inductor" set in the E3 series: starting from 2.2uH, 4.7uH, 10uH... up to 10mH, overall 120 pieces, 10 of each value out of 12.I'm talking about these:https://aliexpress.com/item/10000414499018.htmlPlease recommend me some interesting projects to use these inductors and explore their place in the electronics circuitry.My main area of interest are digital circuits, mainly 8-bit vintage stuff along with some modern uCUs and FPGAs and naturally I don't see any usage for these inductors in this area.Please point me in the right direction where I can use these inductors in real life (preferably not purely academic) projects.Otherwise I could always resort to exploring various kinds of low/high/band pass filters with these inductors but that's not what I would ultimately like to use them for (while I do not object doing that).However I suspect that their intended real life application is essentially nothing more than pass filters in one or another form.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 09, 2023, 10:40:49 pm
content: PoL (point of load) regulators are in wide use, mainly with the smaller end of that range (<1uH to 10s uH, occasionally 100s+). Making a few buck and boost regulators is also a good introduction to switching power and control methods.Tim

author: james_s
author_rank: Super Contributor
timestamp: March 09, 2023, 10:45:05 pm
content: Buck converters and boost converters are the most common things I use power inductors for. And LED drivers, which are mostly buck or boost converters.
Power Input Protection Circuit - Page 1
Forum section: electronics / beginners

author: Thewafflication
author_rank: Contributor
timestamp: December 31, 2018, 12:16:23 pm
content: I am looking at this schematic:https://github.com/MinnowBoard-org/design-files/blob/master/minnowboard-turbot-dual-E-Dual-and-Quadcore/F300_R201/TurbotDualE_Dual_Core_F300_R201-SchematicR200.pdfPage 22.I am trying to figure out the purpose of R132.My first thought was its just a RLC filter to prevent noise generated by the system from getting to the power input?"Normally" with an RLC circuit the R is either in series with L or parallel with C.My second thought was maybe it acts as a soft-start, so when the device powers on it doesn't dump too much power charging the caps that it blows a fuse?

author: mvs
author_rank: Frequent Contributor
timestamp: December 31, 2018, 04:28:03 pm
content: Quote from: Thewafflication on December 31, 2018, 12:16:23 pmCeramic caps have very low ESR, R132 placed in series just increase it. It will reduce arcing, when live plug is connected.Also some voltage regulators tend to oscillate if ESR of caps connected to the output is too low.
Power Integrity - Free Webinar - Page 1
Forum section: electronics / beginners

author: Rich@RohdeScopesUSA
author_rank: Frequent Contributor
timestamp: November 14, 2019, 02:43:38 pm
content: We're hosting a free webinar by Steve Sandler (power integrity guru) on November 20th. Here's the abstract:We will be discussing power integrity issues, root causes, and countermeasures in sensitive electronic designs. Demonstrating best design & test practices and solutions we will be supporting electronic design engineers effectively and efficiently powering their devices and systems. Measurements in the time & frequency domains provide detailed insights in the design verification.Attendees will be learning the impact of noise, jitter, impedance, etc. and examples to detect those sources of power integrity failures. We will be discussing methods to reduce respectively compensate those sources and demonstrating oscilloscope and vector network analyzer solutions engineers benefit from for their design verification.Registration Link:https://event.on24.com/eventRegistration/EventLobbyServlet?target=reg20.jsp&referrer=&eventid=2126146&sessionid=1&key=F9FC539D510F1CA91995049130A7AD15&regTag=&sourcepage=register-Rich
Power isolation - Page 1
Forum section: electronics / beginners

author: Birckcmi
author_rank: Newbie
timestamp: June 25, 2023, 09:06:58 pm
content: Hi. My question: Can I create an isolation transformer by arranging two identical stepdown AC-AC transformers back to back, with the secondary outputs connected, then connecting one of the primary pairs to incoming AC and the other to my intended power supply, or light dimmer? Would the output be isolated?

author: Benta
author_rank: Super Contributor
timestamp: June 25, 2023, 09:16:53 pm
content: Yes, certainly. It will even be a very good isolation setup.Expect that the output AC voltage will be a bit lower than mains voltage due to losses.

author: Birckcmi
author_rank: Newbie
timestamp: June 26, 2023, 11:02:17 am
content: Thank you. The slight drop in voltage is acceptable, since the next stop for the power is either an AC-DC 24V power supply or a heavy-duty dimmer switch for varying the output as AC. But I don't even want to mess with that next step unless I have isolation in place. Thanks again.

author: MindBender
author_rank: Regular Contributor
timestamp: September 05, 2023, 07:04:32 pm
content: Quote from: Birckcmi on June 25, 2023, 09:06:58 pmThat fully depends on the construction of the step-down transformers you are planning to use. Many step-down (and step-up) transformers, do just that; Stepping down (or up) the input voltage, butdo not galvanically isolate the output from the input.The reason for this iscost reduction. Most of them make use of amono-transformer, which is a transformer with just a single winding (coil). This single winding has a center-tap, and by applying a voltage to the full winding, half of that can be taken from the center tap. Please note; This isnota voltage divider. It works magnetically. Because if applying a voltage to the center tap, double the voltage can be taken from the full winding. Other well knownmono-transformersarevariacs, variable transformers.So measure continuity between inputs and outputs, instead of trusting it is isolated. And open up the transformer housing when in doubt.

author: TimFox
author_rank: Super Contributor
timestamp: September 05, 2023, 07:09:38 pm
content: The other term for a single-winding transformer with taps to change voltage without isolation is "auto transformer".Almost all variable transformers (VariacTMis a trademark) are auto transformers, but a few have two windings for isolation.However, in my experience more step-down transformers have two windings than have one winding: if there is a large step-down ratio, the wire size for the winding or winding section that supports the lower voltage needs to be larger because of higher current at lower voltage.It never hurts to check, either the diagram (if supplied) or by ohmmeter.
Power Latching Circuit Issue - Page 1
Forum section: electronics / beginners

author: .netNinja
author_rank: Newbie
timestamp: May 15, 2023, 06:21:45 pm
content: I'm working on designing a circuit to latch power to an ATTINY85 when a button is pressed, then turn the power off when the button is held, but for some reason. The below schematic is not working. Does anyone have any ideas? When I load it Proteus, the 7805 is automatically providing 5v without a button press. I've attached the schematic to this post. Keep in mind I'm kind of a beginner to electrical engineering. I've done a lot with microcontrollers, just now diving into the world of electrical engineering.

author: AnalogTodd
author_rank: Regular Contributor
timestamp: May 15, 2023, 07:51:14 pm
content: The first thing I see is that there is nothing to turn off the two bipolar devices you have in your circuit. All it takes is a small amount of leakage current into the bases of those devices and they will turn on, nothing is there to hold them off. Try adding some resistance to ground from the bases of those devices, something like a few hundred k should work.

author: .netNinja
author_rank: Newbie
timestamp: May 16, 2023, 02:41:44 pm
content: Okay, I'll try that. Am I over complicating a simple on/off latching circuit or am I going down the right path?

author: AnalogTodd
author_rank: Regular Contributor
timestamp: May 16, 2023, 04:40:35 pm
content: It all depends on what you want to accomplish. I tend to go simple with things--a switch for on/off is all I often do, but then again I am usually trying to maximize battery life for small circuits.As for what you have done in the circuit, my only question would be what you are hoping to accomplish with Q3/C2? That's really not going to do anything in the circuit.

author: Eraldo
author_rank: Regular Contributor
timestamp: May 16, 2023, 06:47:54 pm
content: Dave already did a video on the matter. It's quite a simple circuit to buildhttps://youtu.be/Foc9R0dC2iI

author: Kim Christensen
author_rank: Super Contributor
timestamp: May 16, 2023, 10:46:05 pm
content: Take a look at this circuit. When PB1 is pressed, it turns on Q1 which powers up the 5V regulator (It also turns on Q3). This boots up the MCU which then in software makes U1-PD6 high, which turns on Q2, which lights the LED and keeps Q1 on. The MCU does this quick enough that the user can then remove his finger from the button and the circuit can stay powered.But now after a time, when the user again presses PB1, this turns Q3 on which the MCU can sense via it's PD7 pin and the software can then make PD6 go low and power itself off once the user releases the button. The nice thing about this is that the MCU can turn itself off under software control with no user intervention if you want it to.
Power Limiting circuit for very low powers - Page 1
Forum section: electronics / beginners

author: snoozy
author_rank: Contributor
timestamp: April 17, 2023, 09:29:42 am
content: Hi guys,I'm need to create a circuit, that limits the power to a CAN transceiver on the data lines.It is a protection cirucit only and should not be active under normal operation.The power needs to be less than 25 mW on the primary side of this isolating tranceiver in total. That means on the lines CANH, CANL and VCC.My first try was a current limiter followed by a Zener, but I cannot reach such low power levels without a huge shunt, that will effect the function.I was thinking, there might be a way to adjust the reference voltage that is parallel to the shunt to a lower voltage.Thanks for any ideas or pushs in the right direction.
Power Line Communication - Page 1
Forum section: electronics / beginners

author: sagnikbasu
author_rank: Contributor
timestamp: May 09, 2017, 05:11:08 pm
content: Is there any tutorial on implementationg power line communication using microcontroller like arduino ?

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: May 09, 2017, 05:37:58 pm
content: Pretty sure one thread is enough.https://www.eevblog.com/forum/projects/power-line-communications/

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 10, 2017, 01:06:27 pm
content: powerline is a shit.The inter fear with Radio/ Ham and commercial Bands.

author: yada
author_rank: Frequent Contributor
timestamp: May 10, 2017, 03:48:02 pm
content: Quote from: alexanderbrevig on May 09, 2017, 05:37:58 pmWhen some one doesn't answer your question just keep reasking it in different threads. That doesn't make a forum go to shit fast. Usually if no one answers its because you are in the wrong forum or there is no simple answer.Best way to communicate over the power line is to take an old school telephone and connect the red and green wires to the black and white wires on the AC side. Add as many receivers as you need communications points. OR you can just directly connect the white and black wires to your arduinos digital inputs... or analog, it won't really matter. It will send exactly one bit of data. Data will be either a 1 or 0 and can be read by the position of your circuit breaker switch. This acts as a digital inverter gate : when the breaker reads 0 or off that is considered a 1. To send an eight bit signal try hooking eight arduinos up to eight different breakers. Get a set of arduinos for each byte you intend to send.
Power Management Unit: How to consider limit to connect electronic component to  - Page 1
Forum section: electronics / beginners

author: chrischina
author_rank: Contributor
timestamp: May 15, 2016, 03:25:06 am
content: I am a bit confused about the way to dimension Power Management Unit, and power rail for electronic system.I understand quite well LDO and DC-DC in terms of voltage, but i don't understand well about current (although I know kirchoff law). Particularly I am confused about the maximum total current that a source can deliver/supply to load in the case of battery powered one. Normally, I suppose that at equal voltage we should add up current to get total current needed, but how to put this in face of battery. Does Lipo battery got maximum current it can deliver to supply many loads ?Let's say we power a system with a Lipo battery 3.7V-4.2V, 1000mAH.The system got: - 1 MCU such as a MSP430 (http://www.ti.com/product/MSP430FR5969) - one auxiliary chip such as RF chip (let's say CC1310, datasheet here :http://www.ti.com/lit/ds/symlink/cc1310.pdf) - one module such as GPS (quectel L70,http://dl.roboticngo.com/uploads/Quectel-L70-Hardware-Design-V2-0.pdf) - one another module such as GSM (quectel M95http://www.soselectronic.com/a_info/resource/c/quectel/M95_HD_V1.0.pdf) - one EEPROM such as ST one - one TF Card such as SD CARD.How do i verify this is achievable to supply all those chip and module with our Lipo battery and how do I build our power management architecture?

author: danadak
author_rank: Super Contributor
timestamp: May 15, 2016, 09:33:10 am
content: Take a look athttp://www.ti.com/lsds/ti/power-management/battery-management-bms-university.pagehttp://www.silabs.com/Support%20Documents/TechnicalDocs/Selecting-the-Optimal-Battery-WP.pdfhttp://www.ti.com/analog/docs/analogtechdoc_hh.tsp?viewType=mostuseful&rootFamilyId=64&familyId=411&docCategoryId=1https://www.maximintegrated.com/en/design/techdocs/app-notes/index.mvp/id/5/c/Battery%20Management#c5Regards, Dana
Power Management - Page 1
Forum section: electronics / beginners

author: desowin
author_rank: Contributor
timestamp: March 01, 2011, 10:59:53 am
content: I'm rather complete newbie to power supply related issues, basically I know about the 7805 and I've watched EEVblog #139 - Let's Select a DC-DC Boost ConverterI'm searching for solution which would handle following:-AA (2 or 4) battery input-car cigarette lighter input-3.3 V output-5 V output (but that's just "extra", not mandatory)If the device is plugged into car cigarette lighter, it should be powered from there - if not, then it should be driven from batteries, integrated charger solution (in case the cells were NiMH or NiCd) is not requiredI heard there're PMIC solutions that could handle that, but either I'm searching wrong, or it's called somehow different.

author: scrat
author_rank: Frequent Contributor
timestamp: March 01, 2011, 11:18:22 am
content: I know National Semi has good online tools, but someone knows better than me. However, I'd try with a parametric search on a semiconductor manufacturer site, as a start.
Power OFF after processor enters power down mode. - Page 1
Forum section: electronics / beginners

author: rakeshm55
author_rank: Regular Contributor
timestamp: January 03, 2019, 04:40:59 pm
content: Hi,I have a processor Am5718 which uses a PMIC TPS65916. Processor has a power ON and Power OFF sequence. Now once i trigger a power off sequence to PMIC, it turns processor power off sequentially.Now I have system power which needs to be turned of after Processor has turned OFF. It is controlled by a switch like LT2955. I need to assert kill pin OFF after processor has turned off. How to do this?? In do not have a board management controller to do this.is it possible to turn off system power ?? I guess before entering PMIC OFF sequencing processor should trigger system turn off after a certain period (time duration should be sufficient to comfortably accommodate PMIC OFF sequencing) kill should be asserted. Is it possible to implement without a controller or PLD??. I want to avoid programming step here.
Power off ESP32 after doing some code? - Page 1
Forum section: electronics / beginners

author: iphatbass
author_rank: Newbie
timestamp: July 13, 2025, 10:31:07 am
content: I have found this power latch circuit online and I'm complete noob when it comes to electronics, I'm good at programming, since I had a lot of experiences with HTML and different Javascript frameworks in the past. So I'm wondering what i should change here in order to control my ESP32 like this:- SPST button switch that will control the power of the device- When this button is in ON position, it should power on my deviceWhen this button goes to OFF position it should trigger some code before shutting itself offI know how I will program this in VS Code, I'm just wondering is there anything that It should be changed in this diagram to suit my needs? You can find a code and circuit diagram of this project athttps://onedrive.live.com/?redeem=aHR0cHM6Ly8xZHJ2Lm1zL2YvcyFBdC0xUUpqTklfTVFiNlAtalhkZklDSXhRVWc%5FZT1hSmxWNkk&id=10F323CD9840B5DF%21111&cid=10F323CD9840B5DF

author: KimLum
author_rank: Contributor
timestamp: July 14, 2025, 08:45:51 am
content: You would need a latching mosfet circuit to do that. You could use the 12V part of the attached circuit (remove: PMOS2, R7 and R8, the rest will work at lower voltages), and have the momentary pushbutton go to "Logic ON"andan input pin on the MCU. When the pushbutton is activated the first time, the mosfet will latch on and power up the MCU. When the MCU turns on, it should wait for the pushbutton to be released before starting its work. When the pushbutton is activated again, the MCU will sense that the input pin goes high and when the pushbutton is released again, the MCU does it's shutdown code before using an output pin to set "Logic OFF" to high, causing the circuit to shut off.

author: Peabody
author_rank: Super Contributor
timestamp: July 14, 2025, 02:57:32 pm
content: The circuit in the original post is a bit different from the description. The circuit uses a momentary switch, so the circuit is push-on, push-off. When you first push the button, that directly turns on the mosfet. Then the ESP32 powers up, and immediately asserts D2, which will then keep the power on after you have released the button. When you again press the button, that is detected at D3, and your code will turn off D2, and the circuit will power down after you've released the button.It would still work if the switch is a rocker. You would just be testing for the opposite condition on D3.The only change I would make is to increase the value of the resistor on D2 from 10K to 100K. That should still provide enough base current for the NPN to work, and would just waste less power.
Power-on circuit from vibration switch - Page 1
Forum section: electronics / beginners

author: darkcastle
author_rank: Newbie
timestamp: August 26, 2016, 08:48:20 am
content: Sorry if this has been asked before. I am trying to figure out a good way of turning on a microcontroller with vibration for a low power / battery operated application. I came across some cheap switches like SW-18020P, which has different sensitivities. Could be used as an input to some kind of latching power circuit? It would need to allow the MCU enough time to keep the latch on or some or enable pin, then it would be able to turn itself. Perhaps the circuit could also allow for the MCU to check if it is still being vibrated. I did some searching, but I did not really find a good example, but there are probably some out there...

author: Zbig
author_rank: Frequent Contributor
timestamp: August 26, 2016, 09:00:03 am
content: With today's MCUs with super-low power sleep states, there's rarely a need to completely power them off, really. Just let it sleep and wake it up with external interrupt.

author: Ammar
author_rank: Regular Contributor
timestamp: August 26, 2016, 11:53:53 am
content: Agree with Zbig. Something like a PIC10F322 or something from the MSP430 range would likely be suitable.

author: darkcastle
author_rank: Newbie
timestamp: August 26, 2016, 11:44:24 pm
content: I am using an esp8266 wifi / MCU I am not sure if the sleep state would be considered super low. I don't really want to add another MCU for turning it on if I don't need to. I was inspired by the EEblog youtube video on soft power up, but I am not sure if it would really work well for this application.
Power over Ethernet - How to find a proper Transformer - Page 1
Forum section: electronics / beginners

author: Ranayna
author_rank: Super Contributor
timestamp: June 26, 2018, 11:40:20 am
content: Hi,as already alluded in a couple of other threads, I am planning to build a Power over Ethernet supply.I have looked at a lot of datasheets, checked availability of reference designs, overall complexity of those designs, and finally took solderability into account.Now a new problem has me stumped...For example, take the PM8803 from ST.Datasheet:https://www.st.com/resource/en/datasheet/pm8803.pdfDesign Example:https://www.st.com/content/ccc/resource/technical/document/application_note/aa/00/34/1b/19/82/4a/da/DM00113368.pdf/files/DM00113368.pdf/jcr:content/translations/en.DM00113368.pdf(reference design)From the datasheet alone, how would I be able to find what transformer I need? Have I missed something in the datasheet, or would that be obvious for someone who is proficient in designing switch mode supplies?Additionally, how would I find alternatives to the transformers used in those designs? For most designs that I have looked at, the transformers that have been used are difficult or impossible to find. Often I cannot even find a datasheet for the correct part. This ST design is an exception, the HA3691AL is available, but expensive.Maybe I have to admit to myself that I do not know enough (yet) about designing such a supply. At the moment I feel like I'm searching for "Lego Bricks" in the huge bin labeled "Internet", without understanding enough of the basics...

author: madires
author_rank: Super Contributor
timestamp: June 26, 2018, 01:01:52 pm
content: I assume that you're talking about the flyback transformer. The type of the transformer core is selected based on several parameters like the switching frequency for example. And you might need several windings for different power rails. Therefore you won't find many off-the-shelf flyback transformers, they are customized for specific designs. For prototyping you could use the flyback from a cheap SMPSU and re-wind it for your purposes.
Power ports in quad unit device - Page 1
Forum section: electronics / beginners

author: Back2Volts
author_rank: Unknown
timestamp: October 14, 2016, 03:09:13 pm
content: I am using Kicad just to draw a circuit with a quad amp LM324. After dropping in the second amp unit and placing a bypass cap I realized the ports and decoupling are already depicted in unit A.Is the common practice to leave the pins in the the other units "floating" or to attempt to remove pins from drawing?

author: Back2Volts
author_rank: Unknown
timestamp: October 14, 2016, 11:05:58 pm
content: After some trying and some googling it appears there is not much that can be done in Kicad, other than to leave the redundant ports unused. (For me, editing the part symbol to have a unique "power" unit is not an option)
Power Rail Monitor Circuit - Page 1
Forum section: electronics / beginners

author: ssashton
author_rank: Frequent Contributor
timestamp: October 18, 2024, 09:48:27 pm
content: Hi,I would like to create a circuit that monitors a 48V power rail that feeds an audio amplifier. When the voltage begins to drop at power-off I want the circuit to pull the amplifier mute pin to ground.I have thought up this circuit using a open drain comparator (output is connected to the mute pin with 10K pull-up) and made aFalstadsim. I would appreciate comments if my design seems sensible or there are any traps I might not have considered?Note that the amp is powered directly from the 48V rail, but the comparator will be powered from a regulated 3.3V that comes off the 48V rail. I believe by the time the comparator looses power, the amplifier will not be operational as it appears to not start below about 18V.

author: Benta
author_rank: Super Contributor
timestamp: October 18, 2024, 10:39:42 pm
content: Just use a MC33164-3 (onsemi) with a voltage divider at the input. Much simpler, and it's designed for the job. Or any other undervoltage detector. There are plenty out there.

author: PGPG
author_rank: Frequent Contributor
timestamp: October 19, 2024, 12:20:09 am
content: Quote from: ssashton on October 18, 2024, 09:48:27 pmYou divide 48V down to about 3V3.Not all comparators powered by 3V3 will work with inputs being close to its supply voltage.I agree that it is better to use IC destined to work as undervoltage detector.

author: ssashton
author_rank: Frequent Contributor
timestamp: October 19, 2024, 08:14:35 pm
content: Thanks, I didn't know there were such simple ones. I had only seen pretty advanced power monitoring ICs.
Power rail spikes from ILI9341 driver - Page 1
Forum section: electronics / beginners

author: Klemken
author_rank: Contributor
timestamp: February 25, 2019, 03:04:42 pm
content: Hello,i designed a complex motherboard for my project and an LCD whit ILI9341 on seperate pcb, whit FFC 50 pin connection in beetwen PCBs. On motherboard i have a cortex m0 MCU, XTR115 for current loop driver, ATB1000 Bluetooth module, opamps, eeprom, 3.3V output DC/DC converter and a ton of other stuff. On the LCD pcb i only have the 2.8TFT LCD whit ILI9341v driver and few AT42QT10 chips for 4 touch buttons. Everything is working perfectly, only thing is that there are periodicals (412kHz) voltage spikes and dips on my +3.3V power rail (from 3.1 to 3.4V). These spikes are not causing any problems, but since this product will go into semi-mass porduction later this year, i want it to be as good as can be. By removing or turning off separate components i found the cause of them to be ILI9341 logics and the LEDs backlight. The backlight produces around 70% of the spikes amplitude, the rest is from ILI9341 logics. What would be best solutions? I already have several ceramic 1206 capacitors right next to LCDs connector, but looks like i need to add more filters. Was thinking of adding a ferrite bead whit a capacitor next to eat to block and remove spikes into gnd?Thank in advance.
Power rails mixed together? - Page 1
Forum section: electronics / beginners

author: smus
author_rank: Newbie
timestamp: February 12, 2016, 06:34:27 pm
content: HiFirst post, long time viewer...I have designed a PCB which should output 9,5VDC and 5VDC.. it does not.. Bare in mind this i my first PSU and first big designI got 230VAC from the mains through a fuse to the transformer. The transformer then outputs 6,3VAC and 12,6VAC. Both outputs then gets rectified to DC (7,5V and 16,5V), the problem is when I power it up, the 12,6VAC fuse blow (keep reading, i did find the reason) with no load on any of the rails.. The 6,3VAC/7,5VDC power up just like it should and turn on the 6,3V LED indicating everything is OK. but so does the 12,6V LED. Somehow the 7,5VDC end up on the 16,5VDC. No short circuits. Both Rectifiers looks to be goodThe reason the 12,6VAC fuse blows is it trying to charge up the capacitor bank on the 7,5VDC rail and overloading the fuseAnyone having an idea why my rails are mixing together?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 12, 2016, 07:35:39 pm
content: When a CT'd winding is FWB rectified, the CT is at VDC/2. You don't need or want a second bridge rectifier.Tim
Power rating for FFC cables - Page 1
Forum section: electronics / beginners

author: slcf2003
author_rank: Newbie
timestamp: September 10, 2021, 04:31:00 pm
content: I'm working on a project that contains two PCBs. One is for microcontroller and I want to route some of its GPIO pins out. The other board hosts all kinds of chips, ADC/DAC, low power rating amps and so on. I expect the power consumption of the second board to be less than 2-300mA under 3.3VDC. For the connections of various data and control signals between these two boards, I would like to use a FFC cable. I was wondering is the FFC cable good for the 3.3V and GND connection, or should I use a different kind of rectangular connector for them?Thank you.

author: YetAnotherTechie
author_rank: Regular Contributor
timestamp: September 11, 2021, 02:14:38 am
content: It's in the datasheets...0.3mm pitch 150mA per contact1mm pitch 1.2A per contactdouble the number of contacts you need for the cable you choose and it should be fine.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 11, 2021, 08:07:33 am
content: With 300mA at 3.3V, the biggest problem isn't what the cables and connectors can take without melting (two contacts in parallel does fine), the problem is loss of voltage regulation due to voltage drop; you may need significant number of paralleled contacts. Or use higher voltage and local regulator per board.Look at the specified resistance of the cables and connectors, it's in the datasheets. Calculate for worst-case voltage drop and see if this is acceptable, i.e. within the limits of the ICs. Short peaks (< 100µs) can be easily dealt with capacitors on subassembly boards.

author: voltsandjolts
author_rank: Unknown
timestamp: September 11, 2021, 08:30:21 am
content: FFC is useful and cheap.If you need more power transfer there are other options, such as molex pre-assembled cables - check supplier stock before committing though.https://www.molex.com/molex/products/family/discrete_offtheshelf?parentKey=cable_assemblies

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 11, 2021, 10:31:17 am
content: FFC cable is deal for this, especially if it's a size that's available off the shelf - LCSC have many options very cheap.Use some extra pins for ground, and spread them along the width of the cable.Avoid anything <0.5mm pitch as it's fragile and fiddly