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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81 views

Low efficiency buck converter

I've seen the circuit below on YouTube. But it has low efficiency and the p-chnnel MOSFET gets hotter as the output & input voltage difference increases (it goes above 100c with heatsink). I don't ...
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Is a solar still a good way to distill water [closed]

I am trying to create a cheap and easy way to distill water, I learned through some research and talking with people that making a solar still is the best way. I really would like a cheap solution to ...
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What is the practical difference between Peltiers of different rated current, e.g., TEC1-12706 vs TEC1-12703?

I'm no expert, but from playing with Peltier modules I understand that, for a constant temperature difference between the two sides, they behave almost as a resistive load, with an almost linear ...
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35 views

DC Motor Efficiency at a given operating point

I'm trying to select a motor for a design application that cares mostly about efficiency. Given a required torque and RPM output from the motor, I feel like it should be possible to calculate the ...
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For superconducting inductors, does the “magnetic current” flowing in the ferrite of an inductor suffer from “magnetic resistance”?

In this answer to "Inductor made out of super conductors", the experiences recounted included "ramping up the inductor" or "charging it up". Absolutely fascinating is ...
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What are the draw back of having multiple smps stages in series?

Application output - 100V 10mA Input - single cell lipo 3.7V 5000mAh overall efficiency > 85% required. I tested Texas instruments power bench. Texas instruments power bench cannot generate ...
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Ignition coil circuit efficiency

I have a circuit which pulses an ignition coil and requires a 6W input. Under load it has an efficiency of around 85% and an output power of approx 5W rms (60kV peak at 1mA). Under very high ...
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18 views

How Estimate Capacity for a Battery If the Temperature is Changing Constantly

It is the first time I am trying to estimate a battery capacity to can use some devices autonomously. I found this equation: ...
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27 views

Battery Ah specs vs actual Wh when charging and discharging

It is ubiquotously stated that Wh = Ah x V. While this is true (at least regarding the units) I have some doubts about the practical aspects of it. Using an example: Let's take a fully discharged (0%...
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127 views

How to estimate a linear power supply efficiency in LTspice?

I have a little transformer that I would like to turn into a 5V power supply. Before building it I decided to model the device in LTspice: The inductance of the primary and secondary windings were ...
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DC shunt motor electrical

A 5KW, 220V DC Shunt Motor draws 2A at rated voltage when running light. If the armature and field resistances are 1Ω and 165Ω respectively, determine its efficiency when running as a motor drawing an ...
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In a non-magnet, excited-coil generator, what percentage of the generator's total output is used to excite the coil?

I am building a DC permanent-magnet generator with the magnets in the rotor. The stator coils are my unique winding. The overall efficiency of the generator is measured with a digital torque meter ...
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Boost converter for powering SD card

I want to use a switching boost converter that has 3.3V output in order to power an SD card. Also, the input voltage is a CR2477 battery, with voltage ranging from 2 to 3 volts. I have seen that an SD ...
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Selecting the right PMDC motor and battery

I'm looking at generating electrical energy from a mechanical input being used to rotate the shaft of a Permanent magnet DC motor. However, i'm a bit stuck with selecting the right motor and battery ...
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49 views

Is microcontroller power consumption directly related to its operation time?

I have to decide on a way to measure the efficiency of an algorithm running on a microcontroller/microprocessor. My thought is that I can use the runtime of the algorithm to complete a certain task ...
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89 views

Dual OP AMP setup circuit supposed to pull 2mA, but where is the other 4mA going?

This circuit uses half of the TI dual OPA2626 (not showing the other half of the OP AMP). This dual OP AMP supposed to use 2mA, but it's pulling around 6.8mA (measured at the Grnd pin and also at the ...
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57 views

Varying PMDC motor shaft rpm, how does it affect efficiency?

I am working on a project to harvest electrical power from a rowing machine by connecting a permanent magnet DC motor to the flywheel of the rower. However, my knowledge of electrical motors, and ...
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34 views

Does the size of switch-mode adapters affect their efficiency?

I know that a rule of thumb to judge the efficiency of a traditional iron core transformer is to look at its size: the larger it is, the higher the number of windings, the larger the core, the ticker ...
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59 views

Why is this device power usage so much power and with such variation?

I just got a wattage meter to try to get a sense of where my electricity usage is going. One of the surprises was my cheap drugstore humidifier, which seems to be drawing 640 watts. I have a huge ...
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44 views

Efficiency test for motor drives

Hey I have a BLDC square wave controller. How to check the efficiency of the controller alone (not including the BLDC motor). Any suggestions ? I have checked with DC load test machine, but what I ...
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What is limiting my BLDC Motor power Output?

I am using a BLDC 3 phase hub motor and recently installed a motor controller rated for 3000watt (I originally had a 1200Watt controller installed). The motor is rated for 500w nominal 800w peak but ...
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Why is there such a large difference in efficiency in these two boost converter configurations?

Here is the datasheet I realize that the converter has to "work harder" to boost a voltage from 2.8V-6V to 48V than it does from 8V-38V to 48V, but I'm curious why there's such a significant drop in ...
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111 views

How to active limit the current from a DC source

I have a source with variable power output during the time because it is shared with another devices and this source has not enough power to feed my load (a battery charger for a 1 cell 4.2V lipo) so ...
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251 views

Designing MOSFET bridge rectifiers for high voltages

I've been looking into MOSFET bridge rectifiers, also known as "zero IQ" rectifiers, as a replacement for traditional diode-based bridge rectifiers. Here's a simple example: The benefit, of course, ...
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How does efficiency of transformer change with respect to primary voltage?

Suppose we have a non-ideal transformer such that secondary load is fixed and we change the voltage applied to the primary side. How does efficiency change with respect to primary voltage? I know ...
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Why do LED headlamp bulbs need active cooling?

I decided to install LED headlamp bulbs in my car in the hope that I can avoid replacing bulbs every year. I was quite surprised to find that I can't fit replacement bulbs in my car due to the bulbs ...
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Computer power supplies usually have higher efficiency on 230V than on 115V. Why?

As seen here in the example, this particular power supply (and most others too) has higher efficiency when running on 230V. Given that computer power supplies are usually required to output a ...
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28 views

Efficiency of induced power

This is a very basic question which I can’t quite wrap my head around. Say you have a wire/coil in a magnetic field in such a way that if you apply a current in the wire it will move. So you charge up ...
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246 views

Boost converter efficiency

I simulated a boost converter on LTspice and have measured the steady-state output power to be 80.49 W and the average power drawn out of the input source during steady-state operation of the ...
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103 views

Are permanent-magnet motors equally (in)efficient as motors vs. as generators?

Given a permanent-magnet motor with an efficiency of 80% that converts 100W electrical input power into 80W mechanical output power, would the motor have the same efficiency if used as a generator? ...
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48 views

Coordination of mechanical and electrical power in electric drives

I want to ask a question to respected specialists in electric drives. It is known that the mechanical power of an electric motor is determined by a simple formula: \${P_{mech}}= M {\omega}\$; ...
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33 views

Boost Voltage before Regulating or vice versa

I have an input voltage from a 3S battery from 7.4V to 11.1V and I need to regulate / boost it to 5V and 12V. So what is more efficient or what is used in industry Regulate the voltage to 5V with e.g....
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Efficiency Test of Permanent Magnet (PM) Motor With Variac&Fixed Resistance

We have a 3-phase permanent magnet motor and want to test its efficiency in generator mode. We can give a mechanical input power with an external motor (torque meter and tachometer installed) and we ...
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48 views

Understanding of torque constant and efficiency of a permanent magnet motor from datasheet

I am trying to understand the efficiency of the following permanent magnet synchronous motor Motor Datasheet (note we are using the medium voltage model), and its relationship with the input voltages ...
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134 views

Running an electric motor beyond its ratings

I ordered a 36V 500W brushed DC motor but unfortunately a 24V one came. I'm faced with the dilemma of returning it and waiting for a month before getting a refund, then ordering a new one and waiting ...
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Are there any modern tradeoffs that come with designing more efficient DC-DC switching power converters?

Are there common metrics that usually degrade (ex. ramp time, line/load regulation, low-load efficiency) when pursuing more efficient designs, especially for isolated converters? If you saw a new ...
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59 views

Headphone sensitivity/efficiency

Most commercial headphones are advertised to have sensitivity greater than 90 dB/mW. But to my understanding, even with 100% efficiency that's not possible (if we use 10 log (I/I0) where I = 1 mW, we ...
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2k views

Heatsink on underside of PCB

I have prototyped some DC-DC converter modules, and they work well. However due to size, I don't have a huge amount of copper pour for them to dissipate their heat. I have used 2oz copper but the ...
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113 views

The relationship between power, heat and efficiency

I've been thinking about this conundrum. Given we use joules to move a metal block over a surface, we do work. So imagine a motor, that spins and pulls a string, moving said metal block over one ...
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154 views

Do smaller transistors improve computational efficiency because they decrease the duration of signal transfer?

There has been a massive improvement of computational power of computers per $ over time. As far as I understand, this has been driven almost completely by the massive increase in transistors per ...
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487 views

How to efficiently read a battery voltage level with ADC

There is a circuit powered by a battery (3V button cell) and another circuit with a microcontroller (Attiny85 in my case) reading perfectly the battery level (through ADC3 pin) each 5 minutes interval....
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433 views

Class A Audio Amp - Improving Efficiency With A Mosfet CCS

I'm designing a class A audio amplifier but am struggling with the efficiency of my circuit. I know of 'push-pull' Class A designs, but only want to use a single output mosfet. I would like to hit a ...
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Astable multivibrator inverter

I'm new to electronics and trying to make an astable multivibrator oscillator. The PSpice simulation doesn't work (it says netlist error when I place a mosfet or a diode) and I get a really low ...
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317 views

What is the equation for mechanical efficiency of a 3 phase induction motor?

I know that mechanical efficiency is n= power output/power input, but I don't know how to find each of those. I have to find the efficiency at full load running speed. I was only given mechanical ...
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104 views

Energy lost in in Peltier device?

Suppose I power a Peltier device to heat up/cool down some water. Then I later use the same Peltier device, in reverse, to convert the separated heat energy back into electricity. I have read ...
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127 views

Aluminum Electrolytic Capacitor - current, power, efficiency

How to find out the efficiency of an aluminum electrolytic capacitor like this one. How to find out resistance of such a cap in order to calculate the time it takes for it to charge up or discharge? ...
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67 views

Determine efficiency, voltage, current from motor characteristic curves

I would to identify efficiency, voltage, current for a particular Brush less DC motor in our lab given characteristic curves. Electrical specifications are The operating conditions are ...
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520 views

How to measure DC motor (used as generator) efficiency using homebrew methods?

Background I'll be making a "micro thermal power station" in the single-digit watt range at home (one-off, educational project. Bear with me). A heat source, likely ethanol, will cause a stirling ...
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126 views

Which is more efficient: A much larger than needed step-down voltage converter, or one rated closer to the actual load?

I'm designing a custom audio system for my electric motorized pedicab. The motor of my cab runs on a 48 V 33 Ah battery, and I have planned to use a 48 V to 12 V step-down converter to simultaneously ...
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3k views

5V vs 12V addressable LED efficiency

Despite hours of googling, I could not come to clear understanding how efficiency of 5V addressable LEDs compare to their 12V counterparts. If 5V is supplied to WS2812, and the red LED only needs 2....

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