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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84 views

Powering nichrome, possible to do it with AC?

I am working on making a little nichrome-tipped pen for wax welding and planning to use a benchtop supply to provide the small amounts of DC needed to heat up the wire. Figuring out the right power ...
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2answers
73 views

LEDs and External Quantum Efficiency (EQE), how to find Light Output Power with test results? How to find power?

I'll try explain everything as clearly as I can as it's slightly complicated. I really need help as I'm quite new to this kind of experiment and work so any help would be extremely appreciated. I did ...
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1answer
58 views

Class J RF Power Amplifier

What is a Class-J Amplifier configuration? Does it work in a push-pull configuration similar to an A/B? How is it physically different to an A/B? Where can I see a basic schematic? I have read ...
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0answers
38 views

DC to AC inverter efficiency

What is the current best efficiency in DC to AC invertion, in the tens of kW region? I'm thinking mainly of battery to AC, which is a fairly stable voltage input.
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2answers
84 views

Does transformer humming cause notable waste of energy?

AFAIK transformers hum because alternating magnetic field causes pieces of laminated core to slightly deform and vibrate and that is simply a byprocess of how transformers work. However for the same ...
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0answers
59 views

Compressor capacity vs input power, Kelvins law

Have got a silly confusion regarding efficiency calculation of AC & Ref. compressors. Here is a sample of specs of an Aspen miniature compressor. ...
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1answer
62 views

What is the effect of pulsed discharge on watt hour (Wh) efficiency of lead-acid batteries?

When discharging a (lead-acid) battery you see a voltage increase (volts rise) as soon as the discharge is paused. source: http://uu.diva-portal.org/smash/get/diva2:461718/FULLTEXT01 In the quest ...
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2answers
119 views

Is there a voltage buck converter which also boosts output current?

Application: solar USB charger. I have a 9V solar panel. I use a buck converter circuit to bring it down to 5V before going into the USB battery charging circuit. Exact components: ...
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2answers
130 views

High-efficiency blinking LED circuit

I'm an artist currently working on an installation piece that requires a little more engineering knowledge than I possess. In short, what I'd like to achieve is a 2 LED blinking circuit with battery ...
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1answer
117 views

3-phase Brushless Motor - Are Volts and Amps at (X)RPM equal/similar when used as Generator?

If I have a Brushless 3-phase motor that spins at 3000rpm when given 6.0A @ 20v (no load) will it produce 6.0A and 20v (or anywhere close) when used as a generator and spun at 3000rpm?? And i suppose ...
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3answers
78 views

Which low pass frequency filter to configure to measure/calculate DC-DC converter efficiency?

I am measuring the DC-DC converter active power (P in watts) efficiency of a TI (Webench) LM3150 PCB that converts 12 to 5VDC. In the answer of question Measuring precisely the efficiency of a power ...
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0answers
70 views

How does temperature affect the performance of an SMPS?

I have an SMPS (laptop AC adapter) rated for 180 W that is presently operating at capacity. The output seems to be limited by internal resistance, but I can't really tell. I'm trying to get it ...
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3answers
129 views

“Efficiency” of Switching Power Supplies and Theoretical Energy Loss

I have heard that switching power supplies that convert, say, 110 VAC to 12 VDC, are very efficient. I understand that the power transistor that is regulating voltage is either on or off and spends ...
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1answer
54 views

Rechargeable battery configuration for 5V

I have 6x 18650 (3.7v) cells. I'm trying to build basic power-bank and wondering what battery configuration would be better for minimizing power loss in voltage regulation/conversion process? Edit: ...
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2answers
47 views

Stepping-down DC voltage (at low current) in the presence of an audio circuit

I'm trying to add a bluetooth audio receiver to an old 12V battery-powered boombox. The receiver board takes 5V and shouldn't draw much current, but I'm trying to understand which type of DC-DC ...
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1answer
489 views

What is the charge-discharge (Wh) efficiency for lead acid batteries at different SoC and charge current 10-35A/100Ah C10?

There is a 1996 Sandia study with the title "A study of lead-acid battery efficiency near top-of-charge and the impact on PV system design" for charge and discharge lead-acid battery amp hour [Ah] ...
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1answer
116 views

Wide input voltage range buck converter/circuit to 3.3V 150mA

I am building an appliance that should work in very wide range input voltage: In some scenarios input is 5VAC, in other scenarios it can be 250VAC. It's not a problem to convert AC to DC, then ...
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0answers
155 views

PWM Chopping current and Decay Modes of motor drivers

This is my first experience with driving stepper motors, so please bear with me. I was looking again through the datasheet of the stepper driver DRV8811 and came across calculations that needed to be ...
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1answer
113 views

Using diodes to increase efficiency

So I have the schematic below and I am to insert diodes into the circuit to increase the efficiency of the circuit (can only insert diodes, not change the wiring). 'Target' is where I want the power ...
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1answer
477 views

DC 5V USB to replace AAA-battery source: down converter

I have a portable lithium battery-powered speaker which takes auxiliary sound input from a single AAA-battery powered pocket radio. The speaker includes a USB port for charging source devices: I ...
2
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1answer
106 views

Inherent exploitability and power state machines

I'm working on understanding power state machines in regard to mobile computing devices. Most of the information on this subject seems to stem from this article. It's not particularly important to the ...
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1answer
50 views

Using distribution transformers vs direct connection to primary switch gear

I am trying to learn more about transformers and low voltage electrical distribution. Say you have a medium sized industrial building with a primary switchboard feeding several load centers ...
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1answer
426 views

How to calculate a circuits efficiency with the help of LTspice

Note that this is not a question for circuit critique (and lots of things could be said about this circuit) but this circuit is only the base for the discussion of further points. Here it is (an ...
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4answers
578 views

Does a 1 watt 660nm LED put out more radiant flux than a 1 watt 630nm LED?

Given two LED chips consuming same or very similar amounts of DC power, One emitting light peaking at 630nm, The other at 660nm, In terms of output of (but light irrelevant to the sensitivity of ...
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2answers
132 views

Looking for an efficient audio amp circuit

It seems like all the circuits that I find are using outdated and inefficient technology that requires massive heat-sinks at anything beyond headphone levels. Is there any particular reason that there ...
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1answer
141 views

Comparison of the efficiency of DC motor current limiting / control methods?

I'm using the wheels and motors of an RC toy car as a simple robotics platform. The car has 2 motors, one drives the back wheels, the other steers the front wheels. The steering motor is stalled by ...
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1answer
178 views

Difference between spectral efficiency and bit rate

I am reading articles about error correcting codes, facing to a term "spectral efficiency". Due to the context, I guessed that it means "bit rate", but I wonder are these two terms equivalent or not? ...
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2answers
263 views

Low voltage cut out switching for a 6v input SLA to 5v output circuitry - or alternative ideas

I am currently modifying a wireless video door phone system with remote door release system, for use with a walking frame, for my elderly mother in-law, who lives alone. The 7"monitor runs a 5v 1a DC ...
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3answers
1k views

What causes old power supplies to start humming?

I have a number of mains-powered devices that have begun humming (I assume at 50Hz, though I haven't measured it). These include clock radios, a speaker system, a lamp (20W halogen with a transformer ...
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1answer
168 views

Real world efficiency of a LM3150 Webench DC power supply design?

When designing a DC/DC step down converter with TI Webench with these parameters: Vin min: 11.4 V Vin max: 12.6 V Output : 5.0 V Iout : 8.0 A Ambient temp: 30 ºC Then turn the efficiency knob ...
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0answers
66 views

Analyse data discrepancies: Efficiency of wire vs current

Please help me explain why the efficiency of the wire does not follow a distinct path (ie R^2 value is low). Graph 1 Efficiency of wire vs current: http://postimg.org/image/p49bzm4ab/ Is is to do ...
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1answer
205 views

Topology for a DC-DC step up converter for a single AA battery with 50V 10mA output

I need to design a very compact step up DC-DC converter for the single AA battery (input voltage 0.7-1-5V) with an output of 50V 10mA. The load should drain in a typical case about 2mA, but in certain ...
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1answer
1k views

Power calculation of a transformer using only current and resistance

If I use \$P = I^2R \$ for primary and secondary will that tell me the effective power being dissipated? Uf I divide secondary power by primary power and multiply by 100%, would that tell me the ...
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6answers
1k views

Why is electric heating so expensive? [closed]

The loss of electricity in transmission and distribution is only 6%, so why is it that electric heating is so inefficient? I would imagine that the generators at power plants are far more efficient ...
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1answer
189 views

Most lumens per watt

I recently started designing a pcb for flashing lights I want to use in a pavillon at festivals, garden parties and the like. Now my question is, can anyone tell me which kind of LED that has the ...
3
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1answer
87 views

Measuring precisely the efficiency of a power converter

I am trying to measure the efficiency of a DC/DC boost-converter in several operating points as precisely as possible. Right now I am measuring my input-voltage and output-voltage with a multimeter, ...
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0answers
629 views

Dual active bridge converter

I'm having issues calculating the power losses associated with the operation of a bidirectional isolated Dual Active Bridge DC/DC converter. The converter is controlled using Phase Shift Modulation ...
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3answers
516 views

More Energy Efficient 1 or 0

Is it more energy efficient to have active high or active low pins (I'm thinking shutdown, reset, active type of pins)? Pins that one would not expect to change very often so they will be in one state ...
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1answer
210 views

Measuring the efficiency/acoustic power of a transducer

I was wondering what was the best and the simplest way of measuring the efficiency of a transducer. Finding the output acoustic power in respect to the electrical input power under a water medium.
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1answer
733 views

How efficient is wireless electricity compared to wired electricity?

I am looking for data showing practical data/information on the efficiency of wireless (induction) transfer of electricity vs. wired transfer. There is some information out there but the source makes ...
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2answers
2k views

Calculating Efficiency of a circuit

I made a boost converter, and now I want to calculate the efficiency of my circuit. I know the formula to calculate the efficiency which is given by \$ Eff = \frac{P_{Output}}{ P_{input}} \cdot ...
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2answers
67 views

Efficiency of a multi-output power supply

I purchased a device labelled "AC Adapter" that labels the input to be 110 to 240 VAC, 50/60 Hz, 1.5A max and the output is labelled as 12, 15, 16, 18, or 19 volts, DC, 4.5A max or 20 or 24 volts, DC, ...
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1answer
474 views

Aluminum winding in inverters

I am planning to buy inverter. I finalized one model; however, I was told that it uses aluminum windings whereas the other model has copper windings. They recomended I should buy the one with copper ...
3
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5answers
568 views

Are opamps as a voltage regulator effcient?

If I setup an opamp in a non-inverting configuration as follows: Vrail+ is 7.5V, Vrail- is GND (0 V) Vin is 2.5V, Vout = 3.3V (in other words, the gain, aka, 1+R2/R1 is 1.32 [V/V]) Iout = 100mA ...
5
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1answer
138 views

How do I calculate the hysteresis losses of a straight line inductor?

In using a particular type of conductor for an antenna in AC frequencies between 3MHz and 30MHz (HF), it was suggested that magnetic hysteresis losses may be significant if the permeability of the ...
3
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1answer
1k views

What makes automotive alternators so inneficient relative to other applications?

Automotive and some marine alternators typically have an efficiency curve with a peak of 60%. Image from http://www.intechopen.com Whereas alternators to other types of applications reach 96% of ...
3
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2answers
1k views

Why are ARM9 and ARM11 processors still used when the Cortex-A5 is more efficient? [closed]

Many consumer devices that require a low-power processor capable of running for several days to a few weeks on a charge still use ARM9 or ARM11 processors. However, the ARM Cortex-A5 is more powerful ...
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4answers
3k views

Calculating Input power from a source

How can I calculate what the current "I" output can i have for determining my Efficiency. I am building a simple linear regulator and is it possible to know during design of the circuit , what the ...
2
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1answer
290 views

Is there a rectifier scheme for tri-phase which is more efficient than the bridge rectifier?

Because of the topology of tri-phase bridge rectifier, every phase is active (i.e.; feeding the load) only for 33% of the time. It feels like we are not fully utilizing all the three phases, and ...
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1answer
713 views

What type of pumps are most energy efficient to lift 200 liters of water over 15 feet?

Trying to design a rain-water harvesting system for our home. A long-term goal for me is to go "off-grid", or reduce dependency on grid-power, as much as possible. My need is to evacuate about 200 ...