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.

learn more… | top users | synonyms

1
vote
0answers
24 views

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 ...
0
votes
2answers
76 views

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 ...
0
votes
1answer
52 views

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 ...
0
votes
1answer
34 views

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 ...
2
votes
1answer
74 views

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 ...
1
vote
2answers
104 views

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 ...
0
votes
1answer
30 views

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 ...
2
votes
1answer
30 views

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 ...
1
vote
1answer
66 views

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, ...
2
votes
1answer
94 views

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, ...
1
vote
3answers
121 views

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, ...
1
vote
2answers
490 views

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 ...
1
vote
2answers
84 views

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 ...
0
votes
1answer
122 views

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 ...
5
votes
4answers
444 views

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?
3
votes
4answers
591 views

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 ...
0
votes
1answer
42 views

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)?
3
votes
3answers
404 views

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 ...
2
votes
4answers
199 views

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 ...
4
votes
2answers
95 views

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 ...
1
vote
3answers
164 views

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 ...
1
vote
1answer
65 views

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 ...
0
votes
2answers
158 views

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 ...
0
votes
1answer
132 views

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 ...
0
votes
1answer
114 views

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 ...
3
votes
1answer
209 views

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 ...
1
vote
2answers
95 views

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 ...
2
votes
1answer
77 views

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 ...
1
vote
3answers
220 views

(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 ...
0
votes
2answers
194 views

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 ...
0
votes
4answers
121 views

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 ...
1
vote
1answer
112 views

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, ...
3
votes
1answer
107 views

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 ...
3
votes
4answers
345 views

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 ...
0
votes
1answer
65 views

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 ...
0
votes
1answer
89 views

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 ...
1
vote
2answers
116 views

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 ...
-1
votes
1answer
78 views

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 ...
0
votes
2answers
124 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 ...
1
vote
2answers
665 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 ...
1
vote
1answer
246 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 ...
3
votes
2answers
215 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 ...
1
vote
1answer
112 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 ...
1
vote
2answers
1k 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: ...
0
votes
2answers
324 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 ...
3
votes
1answer
237 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 ...
0
votes
3answers
283 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 ...
3
votes
3answers
525 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 ...
0
votes
1answer
71 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: ...
0
votes
2answers
79 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 ...