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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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2answers
94 views

Transformer magnetizing inductance

I am learning about transformers and in the equivalent circuit the magnetizing inductance of the excitation branch is supposed to represent the current needed to "set up" the flux in the core due to ...
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2answers
90 views

Receiving power from antenna (Homework)

The question: "At a carrier frequency of 2 GHz, assuming a transmit antenna gain of 3 dBi and a receive antenna gain of 0 dBi, calculate the line-of-sight received power at a distance of 100 m from ...
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0answers
93 views

Power consumption measurement on the bench

I've been using the Atmel Power Debugger to sort out power consumption issues on some µController based circuits... and have been pretty pleased. Unfortunately, it's limited to a maximum of 5.5 volts ...
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1answer
143 views

I need 5v@500mA to 12v@5A for 2.5 seconds every 5 minutes

I've run into quite the problem. I have a load that requires 12v@5A for under 2.5 seconds. However, my supply is a USB 5v@500mA. This is not an immediate load. The load will only need to be activated ...
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0answers
39 views

Hamiltonian-inspired energy function for power grid stability

I'm looking at this paper which proposes an energy function for a 3-bus power system example. I'm trying to replicate the results in the paper but am uncertain about the ...
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1answer
68 views

12 V input to multiple 5 V outputs?

I have that project, where I have as an input voltage 12 V (lead acid battery) and would like to have 4 output of 5 V 1 A that would be switched on and off with a mosfet. I'm thinking which way you ...
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1answer
47 views

Mobile power bank to power electronic system

I am working on a project where I am trying to use a mobile battery power bank as a supply to my system. The battery power bank can provide 5 V @ 2.4 A. The output of this power bank goes ...
0
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1answer
31 views

Can you bridge off of a 240 V Breaker Box that connects to an Intermatic Timer?

I have an Intermatic T104 Timer drawing power from a Homeline Breaker Box for a home swimming pool. I'm wondering whether it would be considered safe to use the knockout in the timer enclosure to ...
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3answers
60 views

portable power supply

My wife has a tabletop light she uses for quilting work. She wants to take it with her to a class that has no access to AC. Output from AC plug to lamp is 12V, 3A. I have searched for power formulas ...
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2answers
60 views

Finding power absorbed by resistor

Data: \$ J = 1 A\$ \$ R = 2Ω\$ \$ R_{1} = 4Ω\$ \$ R_{2} = 6Ω\$ \$ k = 16 \$ - times Calculations: \$ J' = kJ = 16 *1A = 16A\$ \$ J = I_{1}+I_{2}\$ \$ J \frac{R_{1}R_{2}}{R_{1}+R_{2}} = I_{2}R_{2}\...
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50 views

Oscillation of a certain device

Let's imagine that we have a device, for example a power supply. Let's imagine that we are powering a certain load at a certain output voltage. For example we power a 7.3A load at 26.4V. If I connect ...
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3answers
108 views

Diode power consumption

I need to convert from 4 to 3.3V. So I was thinking of a diode, or voltage regulator. Voltage regulators, I know that it uses about 5mA to do the job. How much current a diode uses ? I cant find this ...
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1answer
36 views

Two different power sources with same voltage and current producing different results

I'm working on a little 3D printed robot (Otto DIY) with an ESP8266 and four servos, and I need to feed it with batteries. As a first thought, I considered some 18650 cells I had lying around, with ...
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1answer
44 views

Connecting a Solar Panel and Power Supply in parallel, in order to power up a load

I am using a Solar Module to charge a LiPo battery. The current supplied by the solar module goes into a battery charger IC and from there to the battery. This works fine. Now I want to add an ...
5
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1answer
90 views

Measuring soil resistivity and estimating soil equivalent resistance in a long distance

I'm trying to size the Neutral to Ground resistor (NGR) in the Wye of a 138 KV to 4160 V Delta-Wye Transformer. In order to find the proper value I have estimated the charging current of the system by ...
2
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1answer
66 views

Induction heater requirements

I am working on determining the specs needed for an induction heater I plan on buying or building. However, I’m having trouble calculating the potential current draw and wattage needed for my ...
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0answers
96 views

Overshoot/undershoot issues in load current wave form of a MOSFET

We have designed hardware circuit which validates voltage regulator maximum output current. So we designed op-amp circuitry to control gate drive of the Power MOSFET and it will work in active region ...
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2answers
53 views

Maximum output power of a PA

I was discussing with a friend about maximum output power of a (class A/B power) amplifier (for example if the device following the PA can only tolerate a certain amount of power). If the input power ...
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1answer
67 views

TDA1085 power supply question

I am planing to design a controller for a universal washing machine motor based on the TDA1085c. While designing the schematic, i have some problems to understand the sizing of some resistors. Here ...
1
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1answer
41 views

Pager system charging pin and socket

Does anyone know what these pins are called? This is a pager from paging system used in certain restaurants. I'd like to know what it's called as I want to use it in my device's design. I need to know ...
1
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1answer
16 views

Building accessories for a Powerstar LiFe battery

I have a Powerstar LiFE battery with 4 pin XLR outputs. The outputs are listed as being 8 amp outputs and 3.5 amp outputs. Does this mean that they will output up to 8 and 3.5 amps or does this mean ...
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2answers
53 views

Powering a project from a car cigarette outlet

In my car boot there is a cigarette style power socket, I have a one of these: https://www.amazon.co.uk/gp/product/B077D71HXY/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 I also have an Arduino ...
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2answers
78 views

Is it possible to wire a regular power supply cord to a sewing machine motor so I can use it for a Halloween prop? [closed]

If it is possible to wire a regular cord (power supply) to a sewing machine motor (with a motor speed controller), what volt/amp supply do I need to use?
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1answer
92 views

Voltage drop when switching FET

I am working on a project which will be switching LED strips with a max of 2A. As a test I have connected a 20W hallogen light. When I try to switch it I get a voltage drop as can be seen in the ...
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0answers
91 views

Safety Capacitor Selection

When selecting an X2 safety capacitor what must be taken into consideration. There are only a few types of capacitance ranges and seem to be chosen based on voltage rather than capacitance. Take ...
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1answer
65 views

Power Supply Pumping

A similar question has been asked, but I wanted to get to a more fundamental understanding of when, in general, power supply pumping occurs in a class D amplifier. In general terms "power supply ...
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1answer
46 views

Select heat sink under pulsing current

I need to design a heat sink for a power supply based on a LM338 with PD= (12V-5V)*2 A=14 watts. That power come from a 24 vac to 12vdc adapter( Inside an A/C unit). That Power supply is for a ...
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3answers
48 views

Can a 24VDC 14amps rated power supply provide more current than it's rated?

I am having some problems with understanding power supply. Can a 24VDC 14A rated power supply provide more current than it's rated? I thought the maximum current the power supply can provide is 14A. ...
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1answer
66 views

Options for powering 5 V from 24 V AC relay switch

I have four switching relays with internal transformers that control pumps for my heat. From what I can tell they are powered by 120 V and it's stepped-down to 24 V that is sent to the thermostats ...
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2answers
40 views

Powering 3 identical laptops using a solar panel

I have 3 identical laptops rated at 45W and 20V. The combined wattage of all 3 is 135W. I want to charge these laptops via a solar cell. Do I go for a solar cell rated 135W 20V or one rated 45W 20V?
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2answers
50 views

JL audio amplifler

I am wanting to add a 700 watt amplifler on my boat but I am having a very difficult time routing my wire on this house boat. I thought of putting in a 110vac circuit (20 amp) to drive a 12vdc power ...
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1answer
80 views

Safely housing a power supply

I'm building a 3-d printer, which will be driven by a smoothieboard. This needs a 24V power supply. I've bought the one shown below: What I don't know is how to house this safely. I think there's ...
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1answer
53 views

Why the distribution network have 4 wires ( not neutral)?

In a real network the distribution lines were 3 lines (ABC). At one pole the lines became 4 lines which are ( ABBC) the phase B split to two lines . Could you please illustrate why they split them to ...
6
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3answers
2k views

Does a dimmed LED lamp draw less power than one at full brightness? [closed]

Does a dimmable 6W LED lamp, dimmed to 50%, draw c. 3W? Or does it still draw the full 6W?
1
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1answer
51 views

Spectral analysis of spectrum analyzer

Using measures from a spectral analyzer, I am a bit confused on how to properly compare the power of each spectral line with the fourier coefficients (Parseval). Take this signal: Take it's spectrum:...
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1answer
41 views

Where does the indicated negative voltage terminal lie on this circuit?

Does the negative voltage terminal lie after the 150v source ?
3
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1answer
120 views

Finding R for max power deliverable to R and determining the max power

This relates to max power transfer. Here's my circuit: simulate this circuit – Schematic created using CircuitLab My goal is to try and find the value of R for the maximum power that can be ...
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1answer
119 views

STM32 power down procedure

This is my first time to design STM32 circuit and I have no experience about the power down procedure. In my opinion, it may be very rude to shut down the power supply as soon as the user presses ...
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2answers
85 views

LED light strip vs. incandescent light bulb power consumption ambiguousness [closed]

Formula for power is: P = I * U or Power (Watt) equals Current (Ampere) * Voltage (Volt). For my LED strip (5 m in length), it says power consumption is 18 ...
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1answer
66 views

Difference between more batteries and boosting voltage

For example if i need 18V for a project, what is the difference if i use 2 9V batteries and 1 9V battery boosting it to 18V? Thanks in advance.
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1answer
51 views

Confusion with derivation of average power formula [closed]

I know that average power is equal to \$VmIm/2 * PF\$. I can show that this is equivalent to \$(1/2)Re(VI^*)\$ by writing VI* in magnitude phase form. However, I also know that complex power \$S = ...
6
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2answers
219 views

Difference between [W] and [WS] power rating of resistors

I see some datasheets of power resistors where power ratings are in Watts [W] and some in [WS] which I don't know what they mean. What is the difference between them? Example of datasheet Some ...
0
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1answer
231 views

How much current does an 1602 LCD draw? [closed]

I want to know how much current a 16x2 (1602) LCD draws when the backlight is OFF and ON? NB: My multimeter is broken.
0
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2answers
72 views

Intermittent power dissipation calculation on TO-220 package

For a certain application I will be using this resistor. I might also go for this other resistor if needed. The working conditions are: Ambient temperature (max): 70 ºC Power to be dissipated: 15 W "...
2
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3answers
319 views

What is the technical name for fan that produces electricity?

I'm wanting to create a wind powered LED similar to this one, but weather proof. I know there's tons of them out there, but I'm wanting to build it from scratch. My issue is that I'm completely ...
0
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2answers
100 views

MOSFET's getting too much heat up without any load

I am working on inverter, MOSFETs in h-bridge inverter goes heat up without any load attached. I also attached pull-up and pull-down resistor on it. here is my circuit duagram. EDIT Sources of PMOS ...
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2answers
50 views

dBm addition question - powers, logs

I'm just a bit confused. Consider an example where an antenna receives two signals - one with a power of -25dBm and one with a power of -47dBm and we are asked to find the total power received by the ...
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3answers
110 views

3 phase unbalanced lighting system

I am working at oil pump station plant as electrical technician, I have 4 years experience in the field, and I face a problem which you can help me with. I appreciate any kind of information that will ...
0
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0answers
40 views

Power of random signal in AM

I'm trying to wrap my head around this problem : I must admit I'm pretty much blocked from the start, at a). I don't understand how I could derive the power of \$s_{AM}\$ given the frequency of the ...
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2answers
83 views

Measure average and instantaneous pulse power

1) How to calculate average power by having voltage and current waveforms of one oscillation period that looks like this? Someone suggested me to use: Won't this integration result in "negative ...