Questions tagged [power-electronics]

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Can I use a PWM motor regulator to control a LED string?

I recently bought some LED Christmas lights, but they are too bright. So I was thinking that maybe I could regulate the output by using a PWM regulator? My LED lights have an output of 30V from the ...
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30 views

Implications of different LCD tecnology

https://www.techspot.com/article/2322-display-tech-compared/ I appreciate that IPS panels use a parallel alignment of crystals and they rotate, while VA panels use a vertical alignment and they tilt. ...
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28 views

What to do with the high dv/dt on bridge H?

I have an H bridge, with a 540V DC link. There is a high level of noise induction across the board (even though all circuits and sources are isolated). Bridge H has drives that provide dual power (+...
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1answer
37 views

How to know which opto-coupler is suitable for high current application?

I would like a suitable opto-coupler to use as isolation from a 12V and around 30A current and another for 5V and around 30A. Are there any good opto-couplers for those ratings?
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Is there a way to output a variable from matlab simulink function block and use it to specify other parameters?

This function block outputs 'phase' which I then want to use as a variable like this: But as you can see simulink throws an error. I tried using Simout but it doesn't work. I am sure I am missing ...
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24 views

Voltage drop on amplifier signal after LED switches on

Circuit above shows my design for amplifying PIR sensor signal, which I then feed to Arduino and based off this signal I switch a LED on. Both, the LED and PIR sensor, are on the same voltage rail (9V)...
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1answer
53 views

How to Supply two different DC voltages using High Current

I'm trying to function a 12V stepper motor(>2.5A) and five 6V servos(>3A). Are there any reliable circuits that can output both these voltages and a high output current since there will be some ...
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60 views

DIY BLDC ESC problem is causing MOSFETS and motor to get very hot very fast, HELP

Hey everyone this is my first time reaching out to the community for help to see if someone can show me what I'm not seeing on this. Basically I am trying to make my own ESC for a BLDC and before ...
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3answers
43 views

AC/DC Laptop adapter power losses

I have a laptop power adapter shown in the picture below. It is written there 170Watt INPUT: 100-240V ~ 2.5A OUTPUT: 20V 8.5A I believe for AC Input they mean Root mean square voltage/current. for ...
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2answers
86 views

Why design chargers with USB port on a side rather than top [closed]

Edit 3: the question being closed due to being opinion based? The design causes problems that are not in the other design, there are no benefits provided for the restrictions that the design imposes, ...
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1answer
53 views

Modeling a simple capacitor

Hey guys I am trying to model the performance of a hypothetical capacitor. Capacitance depends on its geometry, but the charging and discharging of the capacitor depend on a resistive load within the ...
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0answers
39 views

Can a semi-conductor cooler be powerful enough for a room? [duplicate]

I see semiconductors used for small fridges. I cannot find one large enough to cool a room (in place of a conventional Freon based, window air-conditioner). What engineering problems might a up scaled ...
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11 views

Does electrolysis of warm water differ from electrolysis of room temperature water?

Typical energy efficiency of water electrolysis is about 75%. Will this change with the temperature of water?
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1answer
159 views

Does electricity go through non-metal materials or not?

Ever since I was a little boy, I've always had this idea that electricity can only go through metal materials. For example, if I put a 100% metal screwdriver into the socket in the wall, I'm going to ...
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2answers
106 views

Why doesn't the European Type F plugs use a regular earth pin?

Plugs and sockets tend to differ between countries. Though many different standards exist the vast majority have one thing in common: The pins (earth included) are attached to the plug. However this ...
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1answer
79 views

Line to line voltage

I have a question regarding power electronics. What is the meaning of 'line to line voltage' what does it tell us and how can this be calculated. Say I have a three phase system how would one find the ...
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1answer
40 views

How to match a circuit relay online

I don't know where to turn to get an answer to this and I hope this is not the wrong setting to ask for this. I am looking for this Song Chuan relay ( and I prefer not to order it clear from China. ...
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1answer
56 views

Power Electronics Project

Can I use 220-12v,1.5 Amps Stepdown transformer along with 12V 2A (KBP200) bridge rectifier to build a charger for 12v, 7.5AH battery or I should use transformer with Higher output, maybe 15V
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48 views

Why using Tyristor (SCR) for inverting the DC voltage in HVDC systems?

In High Voltage 3 PHASE Transmission Systems the voltage needs to be rectified (from the AC generation source to DC), transmitted, and then inverted back (From DC to AC). For doing this, usually LCC (...
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1answer
53 views

Can a level shifter convert power from 3.3v to 5v and then back to 3.3v?

I need a digital output from a raspberry to power a stepper driver that takes 5v as input. After that, the output from the stepper driver must be converted back to 3.3V because a Pi can't handle 5v on ...
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0answers
21 views

Solving single phase no load transformers questions

1000/100 V, 10kVA, single-phase transformers impedance referred to HV side given as (5+j10). The no-load power of the transformer is given as 300W. What is the efficiency of the transformer at full ...
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5answers
218 views

Preventing a DC motor from stalling

My team is trying to build a mechanical cannon for a final project for a course and we are running into some problems with our motor stalling. Our motor stalls when the plate hits either side of this ...
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1answer
55 views

How do I reduce the mains spike in a switched mode PSU?

I have a switched-mode PSU for a gaming laptop. It has a bad habit of burning out the switches on mains extension panels when I turn it on (two in the last four days). The turn-on surge is always ...
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0answers
19 views

Calculating kWh two-phase alternating network 3 wires

I want to do a project to measure electrical consumption but I have the following question: How to calculate kWh consumed in a 3-wire biphasic network? Example: I have the following chains on the ...
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2answers
20 views

Cheapest way to connect ignition coil to spark plug for use in non-motoring application

I don't know the first thing about how engines work, but am trying to make a spark with a spark plug and ignition coil controlled by a power MOSFET. While trying to find a way to connect them both, I ...
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2answers
90 views

What is the function of jumper pins on a 4 channel relay?

Attached is a picture of a 4 channel relay. I have searched the internet for the function of the jumpers circled in red. They are labelled Low Com and High. On all sites which I have looked at they ...
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0answers
33 views

Electrical component most likely to fail in window AC unit after power surge?

I have a window AC unit, 115 VAC, 10 amps. Power went out earlier in the week due to the big storm on the east coast and once it came back on every LED on the control panel was lit (not typical) and ...
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1answer
1k views

What are the LENOVO YOGA 3 USB-like inlet 20V 2A wiring/signal/voltage specs?

I have an unknown-history Lenovo Yoga 3 Fold-Back Keyboard Laptop that I am trying to charge/test/repair I and don't have a OEM or aftermarket power adapter. The power input site looks like a usual ...
2
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1answer
23 views

AC Harmonics on a system appearing as DC

I have a theoretical question about harmonics and DC. Given I have a circuit which has a power supply providing an AC input(230Vrms @ 50Hz), this then goes into a load which, takes this supply ...
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33 views

Low accuracy current feedback measurement in motor control

Given a very low accuracy current sensor in a 3 phase inverter (in my case used for motor control) what is the best way to tackle the issue and keep reasonable performance and robustness at the same ...
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1answer
30 views

AC voltage b/w DC power supply o/p and Ground

I have various Phoenix Contact Mini DC Power supply units (Pheonix Contact MINI-PS-100-240AC-5DC). It gives the correct DC Voltage across output terminals, as its supposed to. But I also noticed that ...
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2answers
188 views

Effects of Solar Shield on Electronics Enclosure

I am designing a prototype of an electronics package that will sit out on a pole in the sun 24/7 with a max ambient temperature of 50˚C and at 30˚N latitude. It produces 50W of internal heat ...
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1answer
53 views

Why do most BMS systems for li-ions and li-pos stop discharging at 2.5V? Are there better systems or is this the standard

From what i've read online, 3.0V is the absolute maximum li-ion and li-po batteries should be discharged and around 3.2-3.4 is preferable for preserving battery life. if that is the case, then why is ...
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1answer
72 views

What is this gigantic high-tech cylinder in the corner of a middle-class Chinese family's living/dining room in Shanghai? [closed]

My guess is that it has something to do with the climate, but why is it so big and cylinder-shaped? I guess it could actually be a fridge, but it looks too oddly shaped to be that. But maybe. The room ...
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1answer
27 views

Emulate normally closed relay with 2 normally open relays

Good afternoon, I have recently ordered a normally closed relay to fix on my car's daylight-running lights. When the main lights come on the DLR should switch-off. Unfortunately amazon has delivered ...
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1answer
52 views

Is it still a bad idea to keep modern electronics plugged into the charger cable for longer than necessary?

I have an "DaVinci IQ" portable vaporizer. Since the battery quickly runs out of power, I often keep it lying next to me, plugging from the computer into its USB-to-Mini-USB (or maybe it's Micro-USB --...
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1answer
41 views

What's the function of those coils there?

What do they do? The aux contacts are normally open and the device is MR PQM 500 reactive power compensation system.
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1answer
15 views

Maximum amps from a switching voltage regulator

Looking at a part like this LM2596 It is rated for 3Amps with a voltage range from 3.3-12 volts. Does that mean that this voltage regulator will only output a maximum of 3amps?
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2answers
158 views

Designing a loaded voltage divider?

I was wondering how to design this circuit in depth, since I have no idea what to do.
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1answer
749 views

Why is it bad to run power through BNC (RG58) cables?

A standard practice in many academic labs, which I'm told is "bad practice", is to use RG58 cables (i.e. standard BNC cables) for power distribution. Question 1: Why is this considered bad practice?...
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1answer
335 views

How do multiple enphase microinverters stay synced to the grid?

In a prior question it was established that any string or microinverter that is grid tied must put out sinusodial power. But there is also the task of being in sync with the grid. It seems from ...
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0answers
59 views

phase loss detection

Hi I use this circuit to detect phase loose, so if one of the phase lost , the phase loss signal will be high, the problem in this circuit are. 1-if the input voltage less at 50% it give phase loss , ...
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1answer
71 views

Electronic symboles in datasheets

I found these symbols in a electronic datasheet.. Are these all logic gates? or another?
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2answers
61 views

Electronic component datasheet handling

What is $V_{IH}$ and $V_{IL}$ in datasheets? I found High-level input voltage and Low-level input voltage on the datasheet?
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1answer
47 views

Effect of high frequency welding near by the electronic things

I have high frequency welding machine. During the welding time, I can see a wave in my lap and computer and also that time stuck my computer.Can you please help to solve this problem?
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1answer
13k views

How to detect what wattage that my Windows laptop is receiving via USB-PD?

I don't know too much about USB-PD. I understood that USB-PD requires negotiation between the charger and the receiver. So probably my Windows laptop (Dell XPS 9570) should be able to know the current ...
2
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1answer
138 views

Why does collector current increase with base current in BJT?

The base current in the BJT is due to the recombination of holes and electrons. To neutralize the p region an electron leaves the p region. If we take it the other way round, the larger the base ...
2
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1answer
151 views

Why/when is AC-DC-AC conversion superior to direct AC-AC conversion?

I am currently studying wind power and the power electronics used for it. In wind power a generator is driven by wind, thus the resulting power is of widely varying frequency and amplitude. The power ...
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1answer
63 views

My output is much lower than I expect it to be for my transistor-zener diode voltage regulator

I have created this simulation ( see below) of a transistor and zener diode voltage regulator. The output is supposed to be a steady 5 V. But it is like the top bit s cut, to an approx 4.4 V value, ...
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1answer
37 views

Simulating AC using DC

Is it possible to power an AC motor, using alternating positive and negative DC current? I would assume toggling between each at 60hz would work.