Questions tagged [efficiency]
A measure of the overall effectiveness of a system. For example, in power conversion, it would be the ratio of output power to input power.
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Why is power factor such a meaningful quantity?
In my current electrical engineering course the concept of power factor has been a large topic, defined as the ratio of real power to apparent power. It is a measure of resistive power consumption in ...
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2answers
35 views
How does the power efficiency of an appliance compare using 12V DC or 240V AC with an inverter?
With an off-grid system, if an appliance supports powering via both 12V DC and 240V AC, is there any difference with the power efficiency of either method excluding the draw of an inverter used to ...
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Display Design - would combining OLED with a white source be more efficient?
To be clear, I'm not an electrical engineer, nor do I claim complete knowledge of how displays work.
However, I have done research into displays (televisions, computer monitors, AMOLED phone screens)...
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1answer
24 views
led SMPS converter
Which type of converter is best for an LED light for getting better efficiency and high colour rendering index? We want to design a converter up to 80 Watts which gives indirect lighting and less ...
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3answers
72 views
Portable electronic musical instrument: energy from pressing keys, no batteries: feasible? [closed]
on one hand electronic musical instruments are very nice (lot of features: change tonality, change timbre, small number of mechanically breakable parts ), on the other hand they need external power ...
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2answers
31 views
Pros and cons of centralised vs decentralised power deliver for small devices
How does compare using one power supply for multiple devices vs each device having its own - regarding efficiency eg. power consumption?
Model situation:
Home automation using low power devices such ...
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2answers
98 views
Capacitor charging efficiency with a constant power source
I have a question. It is easy to derive the efficiency for loading a capacitor from a constant voltage or a constant current source, basically because exponential functions and constants are very, ...
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3answers
82 views
Would I get a better lumen output and improved thermal characteristics for the same wattage if I get a higher rated LED? [closed]
I'm planning on building a bright DIY high CRI LED video/photo floodlight out of the following components and considerations:
High-power Neutral White (4000K?) LED rated at 95 CRI
No add-on lens so I ...
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2answers
146 views
Ohms law and LED driver efficiency? How can this possible be true?
I am having a meltdown with a Chinese supplier at the moment and hope dearly that someone can help.
I have an LED driver that is in my mind 28.8W. The output of the driver is 48 V @ 600 mA (48 V x 0....
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1answer
26 views
High energy efficiency through transformers
We are about to build a large facility, using lots of electricity. The facility is being built in module form, which are copies of one another.
We are unsure of whether the energy efficiency will be ...
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2answers
136 views
Do electric motors have the same efficiency when operating as generators?
Its in the title. I'm just curious and it turns out that either this is such a stupid question that no one has bothered to answer it, or i'm just not good at googling today. I guess I'm thinking ...
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5answers
9k views
How could have Banksy kept an RF receiver running for 12 years? [closed]
I'm talking about Banksy's "Girl with balloon" painting that shredded itself at auction.
I think the general consensus is that he didn't, and that it was set up before the auction (or a couple years ...
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0answers
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Capacitive discharge excess being used for battery recharging
I am currently designing a circuit similar to a cattle prod that is intended to be attached to a drone. The cattle prod is powered by a lithium-ion battery, charging up a capacitor and then quickly ...
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1answer
39 views
Spice model search with advanced sorting functionality
Does anyone know of a search engine like Mouser/Digikey where you can narrow down parts based on voltage/package type/etc., but exclude all results without PSpice models? Unless I'm doing it all wrong,...
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1answer
74 views
Would it be energy efficient for phones to include actual GPS chip? [closed]
None of the smartphones today have dedicated GPS chips in them, they only have a GPS capability that stems from byproduct features of the modem chips. Because of that, the GPS capability is very ...
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2answers
68 views
Waste heat in battery pack - large pack vs small pack?
Are larger battery packs more efficient than smaller battery packs due to "resistance in parallel" rule, assuming eveything else being the same?
As an example let's consider two 48V battery packs - ...
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1answer
72 views
Dell power adapter does not get warm? [closed]
Usually I notice that power adapters get warm whether they are being used to power a device or not.
The rectangular Dell computer power adapters, however, do not seem to get warm unless they are ...
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1answer
213 views
MOSFET vs. relay power efficiency
Newbie question here. I am putting together a remote switching box for power circuits aboard a yacht. The design is for a central Raspberry pi to send orders to a few boxes, each controlling a number ...
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1answer
98 views
Confusing peltier efficiency COP/Volts and COP/Amps graphs question
Is peltier efficiency (COP) based on current and not voltage and could I have any voltage I want and get a high COP if I limit current?
Whats confusing is that one graph shows efficiency based on ...
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2answers
64 views
Smartphone internal charging circuit type and efficiency
USB usually provides 5V (or even more, for example 9V with Qualcomm Quickcharge) and the phones contain a single li-ion cell with 3.5-4.3V, so there must be some dc-dc converter in between.
I wonder ...
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3answers
73 views
Is there a Semisynchronous Buck Topology which mixes the advantages & disadvantages of both?
I was looking at "What is the purpose of using MOSFET instead of free-wheeling diode in Buck topology?" and the referenced PDF which discusses the trade-offs between a traditional asynchronous Buck ...
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5answers
211 views
Rated vs. actual power usage of a linear fluorescent lamp
After having some power issues, I've decided to investigate the largest power drains in our company, and I've arrived at a realization that 128 lights adds up to a lot of power (and that's not even ...
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1answer
69 views
Efficient electronics components [closed]
Imagine budget is not an issue and you are asked to design the most efficient circuit. With efficient, I mean that the power used to perform the functions is used solely for that and is not dissipated ...
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3answers
91 views
Will battery last longer with larger capacity but lower efficiency (high V through LDO) or vice versa?
Given a simple circuit of a draw around 28mA (when supplied 3.3v). I'm trying to maximize run time on a battery, but working with what I've got on hand... I have the following batteries:
5000mAh 3S ...
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3answers
443 views
Square wave to DC voltage with passive components
Good day,
I have a design challenge that I have been thinking about.
Is there a passive and inexpensive system that I can get a square wave (frequency not decided yet, but less than 8MHz) that will ...
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1answer
82 views
power efficiency's definition
Power Efficiency is defined as output power/input power, right?
And there are a little bit different definition of power efficiency ...output power/(output power+power loss).
Is these mean same ...
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2answers
50 views
Wireless power transfer efficiency calculation
So I'm looking into retrofitting a Qi transmit eval and receive eval kit with coils of a larger diameter than the stock ones, then looking at what playing with the separation will afford me for my ...
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3answers
143 views
How to estimate Li Ion Battery SOC?
In a simple model of a renewable energy system, I have a residential inverer and Lithium ion battery system with a round-trip efficiency (for inverter and battery, i.e. ac to ac) of 89% (at 25 degrees ...
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1answer
84 views
What is the most efficient 3-phase to single-phase AC transformer for a home grid
So a friend of mine is getting electrical power installed for an urban site he bought, and I'm just trying to be a good friend by looking into this.
The company doing the installation recommended he ...
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1answer
860 views
Laptop battery and adapter voltage ratings
Considering a 4-cell (laptop) lithium-ion battery, the cell voltages add (since they are in series) to 3.7 V * 4 = 14.8 V. However, the adapter says that it has a 19.5 V DC output. I want to know why ...
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1answer
39 views
Star rating of electrical appliances like AC / fridge
What distinguishes a 2-star rated AC/fridge from the one rated 5-star? What exactly is the technical reason for the difference in their efficiencies? Is it the compressor technology / the wiring / ...
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3answers
309 views
Use MOSFET series resistor instead of shunt for current measurement
If I have a setup where a N MOSFET drives a heavy inductive load (say, 25A peak), can I use the MOSFET's internal resistance to measure said current the same way I would use a shunt resistor?
The ...
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1answer
40 views
How to manage solar panel as backup power source
I have a 12V PC cooling fan (Evercool PWR-1225H12B) that will run on a 12V regulated supply. Said supply is on a 12 hour daily timer.
In addition to the timed supply, I want to have a solar panel as a ...
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4answers
269 views
Is it possible to use a heatsink without a peltier plate?
At the moment I am working on a project which implies LEDs for street lighting. I need to dissipate around 24 W of heat. In order to do so, I calculated how much heat is dissipated into the air, and ...
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4answers
1k views
How can a low efficiency antenna be used for receiving but not for transmitting?
For the reciprocity theorem, if an antenna has a low efficiency in transmission, it has the same efficiency when receiving.
In literature, it is usually said that one shouldn't use a low-efficiency ...
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2answers
248 views
Does the source impedance of DC-AC converter always represent losses?
This is a fundamental theoretical question about power and efficiency of AC voltage source with very low output impedance, for example, a DC-AC converter; H-bridge converter or class E amplifier.
MY ...
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1answer
71 views
What value to use to find complex impedance of a motor?
Output of motor is 3000 W with efficiency of 0.8, so The input power is 3750 W. when I want to find the complex impedance of the motor Z = X + jY i get fail answer when I use P = 3750 W to calculate ...
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1answer
38 views
The relation about FOM and power extraction improvement
I saw some paper,their comparison is FOM or Power Extraction Improvement(called PEI here),and they are related,PEI=FOM*100,when FOM*100,the PEI value will usually bigger than 100%,take 126% or 425% ...
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2answers
90 views
The explanation of MPPT and its main function
I think the main function of MPPT is to find the max output power for us to let the power efficiency become the MAX.
However,i am still not quite understand MPPT.Is MPPT a schematic or an algorithm?...
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1answer
200 views
Efficiency question of # of LEDs for 6 volt 4 cell Joule Thief Flashlight circuit
This is a high voltage Joule Thief circuit simulation I developed in LTSpice. I am sure that it qualifies as a true Joule Thief because, in the picture below, we are zoomed into the "dead" voltage ...
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1answer
92 views
What exactly is the point of specifically 'inverting' buck/boost converters?
I'm planning on generating a negative voltage for a circuit i'm working on, and want to use an inverting buck topology to do this. With the application being battery powered, my primary concern is ...
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2answers
195 views
Long lived LED vs EL Wire Lamp
I'm on a quest to build a small cylinder (1/2" diameter) that illuminates for extended periods of time on a single charge. I've looked at numerous small sized batteries and decided on using 2 LR44s ...
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1answer
321 views
How to calculate switching efficiency of DC-DC Converter? [closed]
I am new to SMPS.
How do I calculate switching frequency of a DC-DC step down converter.
Example IC : TPS54260 http://www.ti.com/lit/ds/symlink/tps54260.pdf
The datasheet says it is meant to work at ...
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2answers
1k views
What is the theoretical limit of lumen/watt for lighting systems?
Nowadays we see LEDs with 300 lumen per watt luminous efficacy. They still waste a lot of power as heat. Now what is the limit of electricity to light conversion? Say we build an LED with 100% ...
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2answers
177 views
I need to drive an LED on a small battery for 400+ hours. Ideal setup for efficiency? [closed]
Now I'm nowhere near en expert in this field. I hardly know what the terms mean. However, I have very limited time to design a product of which requires some knowledge of electrical engineering, I've ...
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1answer
56 views
Energy usage: CPU vs Screen vs Network [closed]
In a modern computer such as a smartphone, what is the relative energy used by the CPU vs the screen (and controller) and network? Clearly the answer to this question is (in so many ways) "it depends" ...
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6answers
2k views
What drives the advancement towards ever faster cellular network speeds? [closed]
I've always accepted that technology advances. Being born in the 90s, everything just becomes faster, smaller, cheaper and generally better if you wait a few years. This was most obvious with consumer ...
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1answer
54 views
LC oscillator V.S. LC oscillator deactivation
I read a paper,and it said using the LC oscillator to start-up will have a very low peak efficiency,about 1%,so they use the LC oscillator deactivation to let the peak efficiency become 33%.And i see ...
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1answer
86 views
The meaning of peak efficiency for boost converter
I found the definition of peak efficiency:
Peak efficiency=\$ \frac{P_{out,max}}{P_{in,max}} \$,at first,i thought if i have higher peak efficiency,and i have the output voltage,which is much higher ...
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2answers
126 views
Why is the peak efficiency of most charge pump less than boost converter,but still can be published in IEEE [closed]
I read some paper about boost converter recently ,and find some author will compare the peak efficiency of their boost converter with charge pump,and the highest peak efficiency i saw is 33%,the ...
