Questions tagged [power]

Where power is a primary concern for the design under discussion. Use the "low-power" tag when that applies.

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14 views

Amplify slow changing dc signal

A slow-changing DC signal goes from 0-30mV and I need to shift it to 700mV-900mV. I cannot use op-amps and need a transistor-based solution. Please suggest.
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29 views

I need help finding the power

I need help finding the power of the 1 ohm resistor in this circuit. Could you guys give any tips or even some clues to find it ? I've been trying for a while with Kirchhoff's circuit laws but ...
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30 views

Identification of connector used in a plastic card printer

2 position power connector (24 V) needs to be identified. Outside dimmentions: 7,7 x 7,2 mm. Pin pitch: 4,0 mm
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1answer
36 views

Start and Close Depending to Engine Status

I have an interesting question, which I really don't know how to do it or it is even possible. Problem: I want to start a computational unit (ex: raspberry pi) when the engine starts. If the engine ...
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1answer
28 views

Dual power sources (PV cell and battery)

I have a small IoT project with a 280 mAh Li-ion battery. My intention is to plug in the device and charge the battery when it dies, but I wanted to extend the battery life and have been thinking ...
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1answer
36 views

Convert Power Supply to 12V + 5V from Chassis Hot-Plug Power Supply

I'm trying to build a custom server chassis for an IoT testbed. We are gutting a Dell R710 PowerEdge chassis for the devices would prefer to use the existing power supply for logistical reasons. It ...
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22 views

Ceiling lights going out [migrated]

About 3 months ago, I was carrying one 1inch pvc pipe through my mudroom to the basement when I bumped the pvc pipe into the ceiling fan in the mudroom. We didn't notice till the end of the day that ...
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1answer
41 views

Data Centre Rack Power Connector options

I am tying to educate myself on the options I have for Data Centre power connectivity in our racks, for both UK and USA Data Centres. I am UK based so have a better understanding of the UK options, ...
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33 views

Capacitors bridging over transformer in insulated power supply

I need an isolated power supply for powering a device that’s very sensitive to current leak (see below). I bought one such isolated power supply from Aliexpress. What surprised me is that there seem ...
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1answer
61 views

Using active BPF to convert a square wave into a sine

I have an inverter that converts 24 V DC to a 48 VAC peak-to-peak square wave with a frequency of 55 Hz. I am then going to use a step-up transformer to output 120 VAC to power some rocket valves that ...
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2answers
103 views

Changing Voltages in a Circuit?

I am in the final stages of building a fully analog synthesizer. Instead of using +10V, GND and -10V, could I switch these voltages to +20V, +10V, and GND to save weight, bulk, and size of a power ...
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1answer
96 views

Load resistor on (very) old toaster circuit

So the other day, my family toaster which is roughly as old as myself (25yrs), burned down. When I took a look at the circuit, I found out that some components melt down completely. One of them is (...
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1answer
31 views

How to calculate the power rating of zener diode for flyback protection?

I'm trying to calculate the power rating for the zener diode I'm using on my circuit for flyback protection. For example, if a flyback event occurs, the cathode of the zener diode is having a 30V ...
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1answer
32 views

Power received by RFID tag

Power calculation from E and H field Following from the previous post above. The user provided me with some assistance however I am still a bit unclear on how to apply the equations provided. Could ...
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2answers
59 views

Improving Flyback DCM Peak Power using CCM

How does CCM can improve the peak power of normal DCM flyback power supply? I noticed that some of flyback converter can operate in both DCM & CCM. During this peak power excursion, the converter ...
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4answers
186 views

Why do French power sockets have a protruding ground?

French power sockets have a protruding ground. Why did they make this decision? I can't see any major benefits from it, it saves some pennies on each power cord, but it exposes the ground connection ...
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1answer
47 views

Rated power vs power output

Could anyone please explain to me the difference between rated power and power output. It says in the instruction book that the power output is 20 mW/ square centimeter but at the back of the machine (...
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1answer
50 views

Power calculation from E and H field

I am using gprMax to simulate my design. The design is shown in the picture. It consists of an RFID system inside a steel structure. The transmitting antenna is placed in the middle of the container ...
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1answer
48 views

FAN6754 flyback converter-overcurrent problem

I have a design 193V output voltage and 700mA current, but when the current drawn from output, the auxilary winding voltage fall down, and IC shut down PWM gate signal as you can see in the attachment ...
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1answer
57 views

How the electric water heater and stove works? [closed]

I notice that some appliances have heating elements such as electric stove and water heater. I know that both of them using heating elements maybe some type of a resistor or something. I want to know ...
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1answer
95 views

What happens to the electrical grid when I turn on a heavy load?

I'm trying to understand exactly how an electrical grid works, and I'm having one simple question that is challenging me. What happens when a new load appears on the grid? I know in practice that any ...
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2answers
66 views

What resistor type is best for use as a heater?

I'm working on a design that requires I heat a bank of 18650 batteries during their operation. The plan is to mount the batteries along with large axial 2W resistors in to a PCB and using small ...
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37 views

Simplest solution for a battery that can supply 24V / 0.5A? [closed]

I've got one of these ultrasonic mist makers (see image below), which I want to run of some kind of battery. This things require 24V and <500mA, which is more power than I anticipated. This is ...
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2answers
46 views

Power dissipation at resonance [closed]

Im reading a lot of contradicting info on whether or not the power dissipated is affected the resonant frequency or not, if so, how do i factor this into an equation? Parallel RLC circuit. Thanks
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2answers
53 views

Power factor calculation of an offset sine wave across a non-ideal capacitor

I got into a discussion with another student while we were studying and we couldn't come to a conclusion. Assume you have a non-ideal capacitor with some ESR and leakage resistance. If you subject ...
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1answer
49 views

DC High Current Power Supply for Electrochemical Plant

I’m looking to build my own high current full bridge rectifier to power electrowinning cells. I need a DC supply that is adjustable 0 - 5 V, and could supply up to ~50 kA (50 kiloamps.) Obviously ...
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1answer
34 views

UPS output max cable length [closed]

I want to add 2x UPS PowerWalker VI 2200 UPS 1200W in the next room. Is it safe to add 2 Power Strip of 6M ? What Cord Gauge do I need ? UPS page https://powerwalker.com/?page=product&item=...
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74 views

Home PC power problem caused by fridge

When the fridge stops / starts I can see the Mouse & Keyboard lights spike or dim, sometimes the mouse stops working. These components are connected to a powered usb hub. I can't use another ...
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1answer
34 views

Latching power button with force-off

There's been a lot of soft-latched power switch circuits discussed here and elsewhere on the internet. However, I can't wrap my head around how to implement the following requirements: Battery ...
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1answer
51 views

How long will a 32v 15A (500Wh) e-bike battery last outputting at 5V 1A?

I hope it's okay to ask this here My e-bike has a Lithium Ion battery (32 Volts, 15 Amps), and it has a USB-A output, marked as 5V and 1A, I have 3 questions: How long will this battery last while ...
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26 views

Faulty AC converter board [closed]

I have bought Dynacord DRP-15, but it seems like there is faulty AC converter board. When I turn it on, only LCD backlight starts to flash/blink fast. It somehow worked one time and when I tried it ...
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1answer
55 views

PWM that can handle rapid on and off cycles?

I am working on a prototype project with a large electromagnetic solenoid. I want to be able to vary the strength of the solenoid via a PWM (preferred), or constant current. The issue I’m having is ...
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46 views

Using Different Voltages in a Circuit?

I've been working on an audio amplifier circuit and found the following circuit. If my power supply generates +10V, -10V and GND would there be any noticeable change in the basic functionality of the ...
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1answer
58 views

Power dissipated or generated through an element

We know that if a current is entered through the positive polarity of an element and exit through the negative polarity, then the power is positive which means that the power is consumed through the ...
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4answers
5k views

Why is the metal tab of a BJT power transistor is always connected to its collector pin?

Until now I thought the metal tab of a BJT power transistor is connected to ground but it seems like it is connected to its own collector pin´as shown in the below illustration: Is there a particular ...
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1answer
40 views

How to connect two inputs to one output for a mains connection

I have a digital switching system in my home that controls the water heaters. One heater is shared between two rooms and I need a connection such that it can be turned on from either room. I'm ...
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2answers
68 views

Misconceptions about layout of DC to DC step-down converters

I have noticed, in my opinion, some misconceptions in the layout of the majority of DC to DC step-down converters. I've seen in many PCBs that the trace that goes to the input of the converter (point ...
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2answers
49 views

Op Amp Power Calculation

I am simulating an op-amp circuit of which a small section is shown in the image. As per power consumption formula, P = Icc * (V+ - V-) + Iout * (V+ - Vout) I tried to calculate the power. I have ...
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2answers
227 views

How to select DC-DC converter topology?

I would really appreciate some help on this one. I am doing my bachelor's thesis/project which requires me to design and construct a DC-DC converter. I have been working on it for a couple of weeks ...
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1answer
57 views

If I have a device drawing 300mA @5V and I need to use a 15V PSU what current rating do I need for the PSU?

I have an application with multiple components and multiple voltages in use and current calculations are giving me a headache. A simplified version of my application would include: 1x device ...
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50 views

Limiting backlight current in an mp3player

I have an mp3player. Its LCD backlight went black. I noticed high current through LEDs. It goes up to 0.9 amperes for 3 tiny LEDs. Its power conversion unit is based on LM2703 and I am not sure if ...
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17 views
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47 views

Sizing Connector and Cables for Inrush Current

Country: Canada Specs of application: Station can draw 2.2 kW, on full load, which rarely (if at all) happens. Station must run on 230Vac Autotransformer is rated for 7.5 kVA Expected inrush is ...
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3answers
452 views

Stabilize voltage input for Arduino nano on a drone

I am doing a small drone project, and the 8V battery provides power to both the motors and the Arduino Nano. I expect a lot of noise from the motors, however I assume that the Arduino Nano power ...
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2answers
60 views

Calculating total voltage/current for 3-phase?

Consider I have a 3-phase generator with the following measurements: Phase 1 (A): 22.8828A Phase 2 (A): 22.9922A Phase 3 (A): 22.9219A Phase 1 (V): 239.7656V Phase 2 (V): 241.8594V Phase 3 (V): 245....
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2answers
58 views

How to estimate antenna transmit power?

I've recently written a program to predict power density around antenna for compliance with radiation limits. One of the parameters required for the program is antenna transmit power. Antenna transmit ...
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1answer
53 views

What do apparent power, real power, instantaneous power and reactive power all mean in AC circuits? [duplicate]

We've just started AC circuit analysis in class, and the terms that I mentioned above popped up all at once. I'm new to the idea of phasors(I usually visualize them as arrows making a certain angle ...
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2answers
98 views

Why do we not include the current source when finding the Thévenin equivalent impedance?

The problem is from Basic Engineering Circuit Analysis, by J. David Irwin, Robert M. Nelms, chapter 9.3. When I tried to solve this problem, I tried to find the Thévenin equivalent circuit by ...
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1answer
30 views

An IC to manage Solar, USB and Battery supplies

I've been looking for an IC to manage my Solar and USB input to charge my LiPo and power my circuit and I found this IC. It seems to be able to automatically switch between USB and Vin to charge the ...
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34 views

IC Protector in AV Receiver (ICP-N15)

I'm fixing a Denon AVR-788 AV receiver that won't boot but would turn on with the light in front blinking red. Naturally, I looked to the Service Manual (link goes to schematic) and started following ...

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