Where power is a primary concern for the design under discussion. Use the "low-power" tag when that applies.
0
votes
3answers
24 views
Leading Power Factor effects on electrical System
If power factor comes in leading & showing -0.95. Is there any effect on electrical system? if yes, then please tell me what would be the effects. & how long we keep power factor in leading. ...
1
vote
2answers
72 views
Anti-Crank Power Supply for Car
I have a circuit that draws a maximum on 1 amp @ 11v. Its an ATmega328P running PwM through some Mosefts to run some LED DRLs (Daytime Running Lights).
I want to prevent the situation where, during ...
0
votes
2answers
45 views
Can a 1.3W rated SOT23 MOSFET deal with 0.9 W peaks?
I have a TL431 LDO voltage regulator that uses a tiny P MOSFET in a SOT23 case rated at maximum 1.3W (IRLML6401TRPBF). Can it handle 0.9W bursts of 1 second every 10 seconds without a heatsink?
I ...
4
votes
2answers
79 views
Pulling power off a battery stack at different voltages
If I'm powering a device with a series-connected stack of rechargeable batteries, can I pull different voltages at different points and route them to different components? I need to run a 12V ...
0
votes
1answer
31 views
Amperage in a USB AC-to-DC power converter [duplicate]
so it was my understanding that USB was standardized with 5 volts (V) at 1 Amperage (A), but I've seen wall adaptors with 5V and different Amperage including 1A, 1.1A, 1.5A, 2A, 2.1A, and as much as ...
0
votes
1answer
40 views
Thermistor temperature dispersion
I am designing a thermistor circuit to determine if a nozzle is becoming plugged or flowing freely. My idea is to use a low resistance thermistor and resistor to form a voltage divider that when ...
0
votes
2answers
57 views
Air Core Transformer & Ferrite Core Transformer
What is the differnce between a transformer having ferrite core and another transformer without any core (air core transformer).How these two affects the output power and leakage flux??
-8
votes
1answer
57 views
What came first the power or the light bulb? [closed]
Like the classic chicken & egg problem that has intrigued scientists for years what came first the power or the light bulb? Maybe power didn't come to being until a light bulb could be used to ...
1
vote
1answer
84 views
Device can be powered at 6V or 12V, which is better? Why?
I got this camera and need to power it. Docs say that I can power it both at 6V and 12V, but laconically say also that it should be better to power it at lower voltage, so 6V.
Can anyone explain me ...
2
votes
2answers
47 views
How to trade off connection styes in mixed gnd systems( power gnd and signal gnd)?
I am using a motor driver L6235 from ST:application note.On page 6, it gives me a layout suggestion:
it says that the SIGNAL GND and POWER GND should be connected in a single point: the negative ...
2
votes
1answer
56 views
Power dissipation in Fets synchronous switcher
I'm working on a design that includes a synchronous buck switching regulator and I've been trying to understand how much power each FET will have to dissipate. I've been looking at different ...
0
votes
2answers
74 views
How do I find out whether my switched-mode power supply is galvanically separated from mains?
This question is a follow-up to Does switched-mode power supply feature galvanic separation? : Over there, stevenvh says:
"... a mains connected SMPS, and most of those do have galvanic ...
0
votes
2answers
66 views
Kilowatt hour from Complex power
How can I calculate Kilowatt Hours from:
Complex Power = 1,5 kVA
Electrical current consumption = 10 A
It's three-phase electric power.
0
votes
2answers
99 views
How do I convert 24 V from a car battery to 5 V @ 1A?
I need to make a phone charger using the batteries as source in my boat. Also i would also like to know the heat dissipation of the circuit as i need to use it for a minimum of 30 minutes.
5
votes
4answers
123 views
how should i design variable current source of 4-20mA with 24Vdc input?
I am trying to design current source of 4-20mA variable with 24vdc input. The circuit can read one output at a time and variable from 4 to 20mA.
When input varies between 0 Volts and 24 Volts, the ...
1
vote
2answers
48 views
Powering a custom Arduino compatible - 5V regulator or no 5V regulator?
I'm building a custom Arduino compatible with an ATMEGA328P.
Would it be better to get a 5V power supply that plugs into the wall to power the project and gives me a barrel jack, then connect that ...
1
vote
3answers
49 views
Sizing a solar panel and battery for a simple solar application
I am a novice. I want to correctly size a solar panel and battery for the following application. I will be powering 2, 6 watt cfl lights and a 40 watt incandescent light. I am planning on using 400 ...
0
votes
3answers
70 views
Transformer for Flyback power supply
I am designing an isolated DC-DC converter with an input of 12V and an output of 5V@12A, at the moment, a flyback seems like the best option. I have read several books regarding the subject and I am ...
0
votes
1answer
68 views
Video Frequency through 220Volts power line [closed]
Is it possible to transmit Video Frequency through 220Volts power line? If yes, how?
0
votes
0answers
112 views
How can I close the circuit on a string of christmas lights cut in half [closed]
I need to take a 25 foot long Christmas light string and cut it into a 3rd of its size so I can have an 8 foot string. I have already cut the end with the male plug to 8 feet, and I'm now having ...
1
vote
1answer
66 views
DIY : Powering a single LED with a motherboard's internal connectors
I'd like to power a bright LED (1W or 3W) connecting it onto a power source of my computer, directly on the motherboard. I think about using either a fan connector or directly the ATX Power supply. ...
0
votes
1answer
61 views
power consumption of a 4x4 led matrix
i have a 4x4 leds matrix multiplexed which means i can control individual led with just 8 lines rather than 16. I am interested in finding the power consumption of the grid. The led has forward ...
0
votes
2answers
64 views
Non-isolated mains circuit and Ethernet
I'd like to measure voltage and current for a mains circuit using a microcontroller, and connect this to ethernet. Since I want to have 8 independent outputs, using an isolation transformer to measure ...
0
votes
2answers
97 views
How much power dissipated in a wire?
i"m designing a long metal1 wire. The parasitic capacitors and resistors are callculated.
I want to have an ac voltage at the output end of the line ( 0 - 3.3 V ) at 1GHz.
How can i calculate the ...
2
votes
3answers
97 views
DC Motor Efficiency at Fixed Torque
I am in a muddle here, so thanks for making the effort to have a read.
I understand that electrical power going into motor is given by:
\$P_e=I^2R\$
I understand that mechanical power out is given ...
1
vote
1answer
68 views
Can I cut off the 5v output of the IOIO to the Android?
I'm working on a project using Sparkfun's IOIO for Android (https://www.sparkfun.com/products/10748) where power consumption is a concern. The IOIO board provides the phone with 500 mA charging if I'm ...
-3
votes
3answers
89 views
Help explaining “reactive power” video: lights do not use any power? [closed]
In the following video the poster wonders whether his lights, which do not seem to consume any power are running on "reactive power":
http://www.youtube.com/watch?v=UbKr7aYKSPU
Is the poster of the ...
0
votes
1answer
69 views
Connect different devices (Ground/Voltage mismatch)
To begin with, I realize that voltage is relative but I do not get how to get a common ground so that everything is relatively correct to go in and out of the chips.
The picture summarizes the setup:
...
4
votes
1answer
114 views
How could extension cord detection be implemented in Tesla Roadster?
Googling finds evidence that Tesla Roadster electric car can detect cases when it is plugged in via extension cord.
Specifically this page lists error codes 937 and 9 meaning "extension cord ...
1
vote
1answer
43 views
calculating the spectrum of digital modulation methods
I have just started studying the techniques of digital modulation. The book i am reading only has mentioned the psd of bpsk, bfsk , qpsk and msk. I would like to know, how the psd is actually ...
6
votes
5answers
262 views
Can we measure reflected power in a transmission line?
This is a question related to radio transmission, I hope this is the proper forum to ask it. It relates to transmission lines connecting a radio transmitter to its antenna.
In his book "Reflections", ...
0
votes
0answers
20 views
i am trying to match a power supply to a computer but cannot get the exact volts /amps/ power in a standard psu [duplicate]
As I said above, i cannot get an exact match for the computer I am trying to repair. Which is 12v @ 6.7 amps approx 80 watts. The closest I can get is a 14v -17v unit. is this higher voltage likely ...
0
votes
1answer
54 views
Average Household Power Usage - Distribution Spread
I'm trying to compare energy savings of solid state electric meters over older style electromechanical meters and am trying to find information on how long the average US household spends at each ...
3
votes
1answer
131 views
Safely extract power from USB
I am upgrading the lighting in a model with simple circuit which has 17 LEDs (approximately) plus one or two 555 timers. Presently, everything is powered by 3 AAA batteries. It drains between 150 and ...
2
votes
1answer
103 views
Transmitting power and PWM signal through the same cable
I am working on an Arduino based project, which required to supply 24VDC at 2A and 3 PWM outputs from the main board to the other board. The 24VDC is for powering the LEDs, and PWMs are for dimming ...
0
votes
1answer
58 views
Powering several amplifiers with one power supply
I need to power 5 industrial amplifiers for a project but I am not sure I can use one power supply for all. Here is the amplifier model I will use:
http://www.hbm.com.pl/pdf/a0114.pdf
And manual says ...
-1
votes
0answers
32 views
Are all 12 v dc batteries the same? [closed]
I have this pool skimmer that has 2 motors on a floating boat thats skims the top of the pool as it cleans. It uses a 12 v NiCad rechargeble pack. When it died I bought a 12V Lithium ion batter pack ...
0
votes
1answer
55 views
Frequency of fluctuations in power in an input power design circuit
I am thinking about the following power design circuit in section 6.1 : http://www.arndaleboard.org/wiki/downloads/supports/BaseBoard_Specification_Arndale_Ver1_0.pdf
Is it possible to calculate how ...
3
votes
1answer
40 views
SD Comms Resetting Processor
I have implemented an SD/FAT combination on a Renesas RL78/G13 processor. The SD card is being driven using SPI.
The code has been proven to work on two custom target boards using a 2GB card - the SD ...
0
votes
1answer
79 views
How to Calculate the charge/discharge power of a battery?
I need to measure the discharge power of a battery in general.
At the end i want the maximum charge/discharge power as a function of the state of charge(SOC).
So i need a curve that looks like the ...
-2
votes
1answer
65 views
Power supply for my c-pap [closed]
How long will my truck equipped with dual 750c.c.a.batteries power my c-pap machine that draws 90 watts using a portable power inverter and say a 50' extension cord. Thank you so much in advance of ...
1
vote
1answer
78 views
Linear useage of excess power generation
A friend of mine is fortunate to have moved to a very warm and sunny country, and has installed a photovoltaic system on his property. This is grid tied and any excess that he generates flows into the ...
0
votes
0answers
29 views
over temperature and current limiting question about a power switch: BTS5235
I am designing a cuircuit with BTS5235-a smart power switch from infineon.this is the datasheet of BTS5235
I get realy confused about its datasheet.
1.problem about VDS(Voltage at power transistor). ...
10
votes
2answers
664 views
The electricity grid: what keeps small power generators from being 'driven' by large ones?
This is a two part question and pertains to power generation:
What prevents a larger plant (say nuclear) from turning an itsy-bitsy gas generator into an electric motor and drive current through it? ...
1
vote
1answer
48 views
How to understand synchronism?
In my job, I frequently compile a rough rundown of the power consumption of simple industrial plants. Here, you always encounter a "synchronism" factor, besides how many motors of which power and ...
0
votes
1answer
92 views
Is it important to have common ground between you microcontoller and high-power devices on the same PCB?
I noticed that there are more N-channel mostfets than P-channel mosfets on the market.
Then I realised that probably in many applications, the high powered device runs on a higher voltage and ...
3
votes
2answers
125 views
Splitting a power supply between two circuits
I have two separate circuit boards (clock & radio) that I'd like to place within the same enclosure. One takes 12V, and the other needs 3V. How can I utilize one AC adapter to power both boards ...
3
votes
2answers
84 views
Best practice to switch +V or GND connection?
Consider LAMP1 and LAMP2 in the simple example circuit below:
Which is the "better" practice, using the switching component ...
-1
votes
3answers
79 views
Interpreting the power rating of the refrigerator [closed]
My refrigerator is rated as 130W of power. I need to know how to interpret this. Does that mean if the compressor works for a whole hour then only it consumes 130W? Or is 130W the average power ...
2
votes
2answers
111 views
Wireless transmission of energy through a layer of non-conductive material
Is it possible to effectively transmit energy by electromagnetical induction?
I have a plate of nonconductive material (5-10 mm) and I would like to transfer electrical energy from circuit on one side ...
