# Tagged Questions

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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### Measuring switched mode power supply efficiency accurately for high currents

I hade implemented a switched mode power supply: * 1.2 kW * Input: 12 VDC, 100 A * Output 5 VDC, 240 A I need to measure it's efficiency (power loss/total power) by accuracy of 1%. In other words: I ...
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### Most efficient way to PWM a boost converter

I am stepping up ~4V to 12V to power an LED strip with a boost-regulator. I don't want to run the LED strips (3 leds in series with a resistor) at full brightness so I need to PWM them. Is it better ...
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### Efficient method for isolated detection of AC voltage without a stepdown transformer

What is an efficient method to detect the presence of Line AC power in an isolated method? My first thought would be to use an optocoupler, but in order to do that, you need to supply the current ...
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### What characteristics of a MOSFET should I be looking at? [duplicate]

I'm trying to determine a MOSFET for a circuit I'm building which will drive the gate of an N-channel MOSFET at 3.3v with an available current 40mA (**this will be driven using PWM at 4MHz), the ...
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### Efficient low current buck controller topology

In SMPS there are two sources of loss: parasitics, and the controller. Usually, the load consumes more power than the controller, and the parasitic losses dominate. I have the opposite situation. I ...
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### Why don't we use GaN transistors everywhere?

There has been a lot of research around GaN transistors, proving that they have a very low on-resistance, low gate-charge and are very effective at high temperatures. So why are we still mostly ...
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### Experimental efficiency curve of a buck converter

I made a buck converter, And I tested the circuit under following conditions: Vi = 32V R = 6.8 ohm Fs = 125kHz I got this result: I think it's kinda odd that the difference between ...
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### Switch utilization in dc-dc converters

In the book, Power Electronics, by Need Mohan at the end of chapter 7, it is this image: Relating the output power and the power that the transistor is handling, I want to reproduce this plot for ...
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### Transformer drawing 29x more current than it needs

I have an old transformer (20+ yrs) in a building I manage (GE Model 9T23B3872), it takes 277V 3-phase and converts it to 120V 3-phase. It seems very wasteful. It is drawing a combined 8.7 A @ 277 V ...
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### Two DC DC converter with different output - In series or parallel?

Source: LiPo Battery (13V - 16.8V) Consumer #1: 5V (RaspPi) ~1A Consumer #2: 12V (variouse) 0-3A (plus ~1A if series) DC/DC step down: two LM2596 Which would be the better solution: LM2596 #1 on ...
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### power factor correction and switched power supply efficiency

When it comes to switched power supplies, is the power supply efficiency affected by the presence of a power factor correction circuit? In my understanding power supply efficiency is estimated by ...
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### Power Efficiency of Embedded system

I am designing an embedded system and I am hoping to achieve maximum power efficiency as the system will be running off of 2x CR1620 batteries. In addition to power efficiency, I would like to keep ...
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### Efficient toggle switch

Is there a way to circuit a power efficient toggle switch controlled by a SINGLE button so that absolutely no current from the power source is drawn at it's OFF ...
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### Powering multiple DC gadget(Routers, switches, RPis etc) using a single smps will be efficient than multiple power supply?

I have multiple DC gadgets (Routers, switches, RPis etc) so obviously multiple DC adapters too. I have two spare ATX SMPS. So I was thinking to modify one SMPS so that I can replace all those adapters ...
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### Power Consumption and efficiency

I know that similar threads had been answered but due to the fact that i am a beginner at electronics i would like to verify my measurements concerning about voltage total current and power ...
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### Efficiency comparison between six step and FOC for a given motor

For a given PMSM motor with sinusoidal back-EMF, it can be driven by either six-step (as in drone applications) or by FOC (as in servo control). However, for a given motor and given DC link voltage, ...
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### Where is better energy efficiency in single battery or in parallel? [closed]

When we have LG HE2/HE 4 batteries with 0.002 ohm inner resistance data sheet. Which will have better energy efficiency at 40 W power: Single battery. Two batteries in parallel. As I know, ...
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### Effect of battery internal resistance on its energy efficiency

I am trying to calculate Li-ion/LiPo battery's energy efficiency based on its internal resistance (as far as I see from scientific papers, the battery's internal resistance rises with its ageing, ...
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### Why does this circuit speedup the switching time and reduce losses?

I am a little confused as to how this circuit works: According to this website its function is to speedup charge time of the MOSFET as well as reduce losses. How does D1 and Q2 actually work to make ...
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### Is there a theoretical limit to power supply transformation efficiency?

As I'm looking at some resistive-load applications I'm wondering whether there are any rules that put an upper-limit on supply-matching efficiency. Because if a load isn't matched to the power supply ...
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### How to measure the efficiency of a full wave rectifier?

Given a full wave rectifier (http://www.electronics-tutorials.ws/diode/diode_6.html) with an RC filter on the DC output, how can I measure the efficiency of conversion? simulate this circuit &...
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### Is Stepping Down More Efficient When Voltages are Already Closer Together?

If I was to use a buck converter to step-down my input voltage would I have a greater efficiency if my voltages are close together e.g. 7.2v to 5v compared to 12v to 5v?
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### Running 3.3V MCU from LIR2032 Lithium-ion button cell

Background I wish to power my circuit with a Lithium-ion battery LIR2032 (around 40 mAh capacity). These batteries have a voltage that goes from 4.2V to 3V typically during their discharge cycle. My ...
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### How to classify devices into photodiodes, photodetectors and photocells?

Is there a clear differentiation between the three? For example in terms of efficiency (induced current/incident power)?
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### Practical Approach for getting maximum Power from a DC motor

Theoretically, a DC Machine achieves its maximum Power when back emf is equal to half the applied voltage. Why this condition is not realized in practice ? What is the Practical Approach for getting ...
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### Why more, smaller transistors increase power efficiency?

Transistors, bjt, MOSFETs OK got it. More transistors = better computing got it. But compressing the transistors closer to each in my mind only helps reduce the physical dimensions. So does a CPU or ...
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### Switching regulator efficiency TI LM2678 - measured vs. datasheet

I'm working with a TI LM2678-ADJ regulator (granted, on a breadboard) to power a 40" led strip. Trying to figure out why the measured efficiency is about ~15% lower than what the charts in the ...
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### Light dimming regulator circuit

Here in this circuit, We have the load connected to a diac and triac circuit along with a variable resistance and a capacitor. When the circuit operation begins initially, the energy is stored in ...
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### acknowledgment size for STOP-AND-WAIT protocol

I looked frame size range calculation for stop-and-wait protocol post but I have a similar (?) question. The question states. A channel has a transmission speed of 10 kbps. The transmitted frames are ...
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### Most efficient way to generate 3-4 volts from less than 0.5 to 1.5 volts

I am looking for a way to convert power from a 1 farad supercapacitor charged by a solar cell into enough voltage to power an LED. The supercapacitor will contain up to 2 volts from the solar cell. I ...
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### Measuring Li-Ion Battery voltage during charging/discharging

I am supposed to measure a Li-Ion Battery cell's energy efficiency. For this purpose i have built up the apparatus setup which charges and discharges the battery cell to calculate its energy. One ...
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### Energy efficiency of Li-Ion Battery

My question is that does the energy efficiency for Li-Ion battery varies for different C rates ? For e.g if a battery is charged and discharged at a lower C rate, would it's energy efficiency would be ...
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### PWM motor heating

Every man and his dog are controlling DC motors with PWM. Nowadays microprocessors are popular and offer more flexibility than 555 timers and general mixed signal analog electronic. The song remains ...
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### Transformers and Electric power Ltspice

i was looking for the Energy conversion efficiency of my circuit in Ltspice, but i find out that my Transformers is giving me strange power values i mean with K = 1 the P1 should be equel to P2 but in ...
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### Why so different lumen efficiencies between mains and 22V halogen?

I was looking for data about halogen reflectors I just bought. They are 50W, 230V. On the package I read 320 lumen and that looked ridiculous to me, then I found this document by GE: Halogen Lamps ...
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### (Ultra)capacitor Series vs. Parallel with (Buck-)boost converter

I've seen that many online schematics for using ultracapacitors as power sources place the ultracaps in series in order to increase the voltage that they can be charged to, lowering the capacitance of ...
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### What does it says the transconductance efficiency (gm/Id) in an amplifier?

I understand the concept of the transconductance but it's not clear what does the transconductance efficiency (gm/Id) mean. Since gm is the variation of Id to the Vgs or vin voltage... What is the ...
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### Light effiency or efficacy and watt to heat output

I am on a light forum and there are debates about watt heat output of lights. I'm using my common sense for the debate but can't find the data online to support my ideas. People are thinking that ...
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### Power effeciency of Zener diode regulator

How to calculate the power efficiency of zener diode regulator? Is it correct to calculate it as the ratio of power delivered to load to the total power drawn from input source? If I am correct, ...
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### Maximum output and efficiency for a simple transistor based amplifier circuit

1. Question What is the maximum output over $R_L$ and the maximum efficiency $\eta$ for the amplifier circuit shown below: Below you will find my solution. Is this done correctly? What would ...
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### Switch Mode Alternative to LM7805/LM7905

I am attempting to design a dual rail power supply PCB for a university project. There are a number of restrictions - namely that it maintains > 80% efficiency regardless of the current draw. I was ...
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### How to interpret step-up output current with respect to input/output voltage

I have a Pololu 12V step-up converter (U3V12F12) that I'm powering with a 3.7V 6600mAh lipo battery. The idea was to use it to power a dev board that requires a 12V input. The dev board draws about ...
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### LED array at high current or high voltage?

Is it more efficient to drive LEDs at a high current and low voltage, than a lower current and high voltage? I'm in a situation where I have to design an LED driver for a custom CoB emitter, so can ...
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### Definition of antenna efficiency

I have two definitions for antenna efficiency: $\varepsilon = \dfrac{P_{rad}}{P_{in}}$ and $\varepsilon = \dfrac{R_{rad}}{R_{rad} + R_{ohm}}$ Coming from physics, I was wondering if there is ...
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### 2x50w stereo vs 100w mono amplifier efficiency

Which is better for efficiency. mono 100w amplifier or stereo 2x50w It is important because I'am building a portable speaker and it is really important for me to use little power. Also which ...
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### 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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### 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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### 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 ...