# Questions tagged [power-electronics]

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11 views

### Inductive charging coils

I've been working on a project that requires some wireless charging, at about a 10mm gap. I've found some inductive charging coils on the Adafruit website (part number 1407), but I, unfortunately, don'...
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17 views

### How to find pixel density in LED Display Board?

How to find pixel density in LED Display Board? How do we compare pixel per inch and dots per inch? In this example, a screen of 16'x9' is shown. How did they calculate 4875x2710P and 975x548p and so ...
1 vote
27 views

### Heat transfer: does the heat generated in a cable get transferred to the electrical components?

I have a 1000 V, 50 sq mm, double insulated (XLPE) copper conductor cable. This cable is being connected to a power electronic component. The current flowing through it is 230 Amps DC. The cable ...
1 vote
48 views

### Why do identical-looking power plugs randomly not fit in some sockets in the same power strip?

This has bothered me for many years, but I'm only now coming around to ask about it. I don't know if this is unique to Sweden or something, but for whatever reason, when I try to plug things into the ...
1 vote
60 views

### Why am I getting such conflicting safety advice regarding opening up and dedusting/servicing my CRT TV?

I have asked questions on Stack Exchange. I have watched many videos on YouTube. I have asked professional TV repairmen. I get wildly different advice on the safety of opening my 1989 28" CRT TV. ...
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40 views

### What are some methods of converting electricity without the use of induction or heat?

I was trying to study exactly how current in a wire is used to do so much in our life and how the energy is converted. But the only methods I have found are by using the resistance of the conductor to ...
• 101
44 views

### Would the below thermal generator work properly and provide surplus energy?

Since thermoelectric generators make electricity through thermal flux, could a device that mixes NaOH and HCl on one side (heat) and Ba(OH)2•8H2O and NH4SCN (cold) be efficient? Could it produce more ...
59 views

### What is this component on the face of an analog clock?

I have this decade old wall clock in my house and it has this little component peeping out its dial. I was curious as to what this component is and what it does in a clock. I was into Arduino for a ...
19 views

### Backing up a welder's power source with lead acid batteries

I'm thinking of purchasing a MIG welder sometime in the future. Given, the ordinary mains cannot supply the power. So I would have to plug it through the dryer's outlet, with some adapter & ...
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14 views

### Simplest way to maintain speed of motor? Type of motor for application, speed control required, power supply, etc

I am currently designing a mechanism that will do something like this. The rotating disk will be connected to a motor via shaft coupling. I am going to have a cylinder going through the bore in the ...
21 views

### How to avoid brief power-on surge on ESP8266-driven LED strip/s

I am controlling a CWWW (cold+warm white) LED strip for a desklamp, via ESP8266. I chose GPIOs 4 and 13 for the two (independent) channels. For each channel I use an NMOSFET-based driver (since some ...
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1 vote
36 views

### Flood light pole components

I saw this flood light pole. It has two LED bulbs, but I do not know what the box in the middle is (it was not an LED), could you guys help me understand what this could be? This flood light is ...
• 271
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### Load/power shedding for DIY power generation - how does it work?

I am putting together a simple DIY solar generation unit for an off grid cabin. The cabin will "pull" (i.e. present) a variable load to the generator over a given time period. Suppose I have ...
36 views

### MOSFET pass short spike during power up

I discovered one feature. I've designed circuit for pulse generation and I discovered that it always pass one spike during power up. The circuit is consist of two sections. PMOS for Enable and PMOS ...
43 views

### 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 ...
• 101
31 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 (+...
46 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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42 views

### 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 ...
25 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)...
55 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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63 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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49 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 ...
• 113
90 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, ...
• 119
1 vote
56 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 ...
• 271
1 vote
44 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 ...
168 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 ...
1 vote
147 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 ...
87 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 ...
49 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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60 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
64 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 (...
76 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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279 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 ...
60 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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1 vote
20 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 ...
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 ...
154 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 ...
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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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 ...
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 ...
34 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 ...
1 vote
31 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 ...
• 113
224 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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1 vote
60 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 ...
73 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 ...
28 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 ...
1 vote
60 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 --...
1 vote
42 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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