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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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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0answers
48 views
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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1answer
38 views
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 ...
0
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1answer
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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2answers
64 views
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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2answers
65 views
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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0answers
32 views
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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1answer
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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3answers
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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0answers
38 views
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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0answers
19 views
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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2answers
24 views
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 ...
1
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1answer
31 views
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 ...
2
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2answers
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 ...
0
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1answer
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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2answers
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 ...
0
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1answer
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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1answer
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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2answers
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 ...
0
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3answers
93 views
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 ...
6
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3answers
1k views
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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0answers
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 ...
2
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1answer
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, ...
2
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2answers
45 views
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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3answers
1k views
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 ...
36
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3answers
6k views
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 ...
0
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1answer
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 ...
0
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1answer
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 ...
0
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1answer
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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1answer
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}\$;
...
0
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1answer
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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1answer
24 views
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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1answer
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 ...
0
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3answers
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 ...
0
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1answer
51 views
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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1answer
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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3answers
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 ...
2
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3answers
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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4answers
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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2answers
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....
2
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2answers
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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0answers
69 views
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 ...
2
votes
1answer
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 ...
0
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2answers
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 ...
0
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1answer
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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2answers
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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2answers
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 ...
0
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3answers
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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2answers
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....
