Where power is a primary concern for the design under discussion. Use the "low-power" tag when that applies.

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37 views

Wind energy (using 220v ac motor)

I have created a mechanical section of windmill generator but I am stuck in the power section. Knowing that I used ac 220v motor, how can I convert this unknown and variable ac voltage into dc 12v?
5
votes
2answers
89 views

Two analog power planes for same voltage

I'm designing a board with LAN8720 and LPC1768. LPC's ADC and LAN's magnetics connections require analog 3.3V power. Should I separate these two analog power planes with a ferrite as I separate it ...
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2answers
48 views

How can I know how much power can I generate?

Let's say we have a wind power of 6,831 megawatts. How can know how much power (i.e, megawatts/hour ) it can generate per year?
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1answer
57 views

How to measure power of my device?

My device is working with ten 1 watt LEDs. How can I measure the power consumption of my devices?
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0answers
22 views

Calculating power draw for LEDs and driver (TLC5941)

I am designing a backlit keyboard with 61 white LEDs. These will be individually driven by a TI current limited PWM driver (TLC5941). LEDs: 61 x Osram LCW JNSH.PC (Datasheet) Drivers: 4 x Texas ...
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0answers
38 views

Strange output waveform of the high-side load of MOSFET

everyone. I am using a MOSFET as a switch to drive a laser diode. I input a periodic signal to the Gate of the MOSFET and I obtained a strange high-side load waveform. Here is my schematic. When I ...
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2answers
51 views

Combing two DC voltages, one high volt low current the other low voltage high current

I am a new member and have found lots of useful information on this forum whilst learning about electronics. I am wondering if I connect a low voltage high current source to a high voltage low ...
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votes
2answers
58 views

Converting a 9v Battery powered Device to a 9v dc power supply [duplicate]

I have an old Vivanco MX300 mixer which runs of a 9v battery. I have it in the same place and it's an inconvenience having it run by batteries. Could I use an old AC/DC adapter that would supply 9v ...
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3answers
66 views

LPC1768 Power Supply Design (an unknown symbol)

I have a question about power supply design for a board which use an LPC1768. Below image is taken from http://www.nxp.com/documents/other/IAR_LPC1768_Eval_Board_Schematic.pdf document. There is a ...
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vote
1answer
123 views

Resistor in series and capacitor in parallel to ground

Could somebody tell me why someone would need circuit like that in supply rails? I assume it is for making DC voltage smoother by parallel capacitor. However, my 24V power supply has 500mA output ...
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vote
2answers
166 views

Power switch with slow control signal

I am trying to switch on and off a circuit that draws about 0.8 amp at 12 V. The obvious choice is to set a MOSFET. The problem is that the control signal (the one that goes on the gate of the MOSFET) ...
1
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0answers
20 views

Texas Tiva Power On

I am attempting to power on a Texas Tiva TM4C123GH6PM with an external power supplied by the VCC pin from a generic ESC. In the board, there is a non-soldered pin named VBUS which I wonder is ...
0
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1answer
43 views

Good volts and amps but phone still charging slowly

I am really new to the EE game and am still tinkering. I have built my own portable DC power source similar to a Minty Boost from scratch and plugged it into the USB port of my Galaxy S3 and it ...
3
votes
4answers
327 views

What are some of the segmented displays with the lowest power consumption?

I have to select a low-power display for a solar-powered digital clock. I have looked into numerous technologies, including e-ink. However, I was still unable to compare between them due to the lack ...
0
votes
1answer
46 views

Can an amplifier deliver a higher power for a short burst as opposed to continuously using the same circuit

I am struggling to understand the fundamental power requirements for an amplifier. If I want to deliver 56 V rms to a 7.5 Ohm load I can use P = V^2/R and find that I need 418 W rms. Requiring a ...
0
votes
3answers
88 views

How does a “break” in the neutral wire enable it to reach the full line voltage?

The answer to Is the neutral wire considered safe? states: When everything is working correctly, it should be at most a few volts from ground. However, and this is the big gotcha, if there is a ...
0
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0answers
36 views

USB OTG Host A-Device stops supplying power to B-Device if low on power?

I have been working with Galaxy S3+USB OTG cable and have been successful in using it to power accessories related to a important project I am working on (yay!). However, I observed that the host ...
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votes
1answer
34 views

Sensor & power wire length & connection inquiry

I'm an experienced SW engineer, but a noob when it comes to .NETMF & hardware. I've started working on my first project (garage controller that will monitor & control the open state of the ...
0
votes
1answer
34 views

What is bus hold LOW or HIGH current refer to in the data sheet?

What is bus hold LOW or HIGH current refer to in the data sheet? (Specifically looking at this data sheet for a translator buffer): http://www.nxp.com/documents/data_sheet/74LVC_LVCH2T45.pdf
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votes
1answer
68 views

Strange sound in speakers when the refridgerator goes standby [closed]

I live in a room which has two power sockets and the following devices, as illustrated in this diagram: https://docs.google.com/file/d/0Byu0T6y2SLeENDdvNGVCWHFBWmc/edit All devices look exactly as ...
0
votes
3answers
75 views

Will a dual car charger that shows a maximum output of 2000mA produce a 2.1A current?

I have a dual car charger that states input is 12-24VDC and Output is maximum of 2000mA, but it is supposed to have one port charge at 1A and other port charge at 2.1A. Is the 2.1A output possible ...
0
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0answers
32 views

Disconnect PV string from inverter and connect to charge controller on grid failure

I'm designing a PV system where a string of panels is connected to a normal grid tied inverter, but when the grid fails, I want to switch the string to feed a charge controller that will top off a ...
0
votes
4answers
126 views

Voltage decreases on higher current

I have a circuit composed of Arduino Mini Pro 3.3V and GY-GPS6MV2 (GPS Ublox NEO-6M). I have tried to power it with 3 different sources: 3xAA NiMH in serie connected to RAW pin of Arduino and using ...
2
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2answers
81 views

mechanical load of an alternator

I'm wondering about alternators used in automobiles and the mechanical load that they present to the engine. My question is: what is the relationship between the mechanical load presented by the ...
10
votes
4answers
863 views

SCR in this circuit exploded - why?

Some of our boards have a damaged SCR. I just witnessed one in person today. The SCR actually exploded upon power-on. A part of its packaging material just flew off along with an exploding sound. ...
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vote
1answer
32 views

Help finding maximum power transferred to load RL

This isn't homework, it's just a review problem. The answer is 4mW. I tried working the problem and came up with the wrong answer. What did I do wrong, and how can I solve this correctly? My ...
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3answers
148 views

Grounding a capacitor?

Noobish question. I'm trying to make a dc variable voltage power supply. I will include the schematic which I am trying to build. In the schematic there are two 1000 uf capacitors which I believe are ...
0
votes
1answer
61 views

2N7002 Continuous drain current?

I'm currently looking for some MOSFET's to do some RGB LED lighting with using PWM. I found the 2N7002 in SOT-23 packaging (datasheet). According to the datasheet the MOSFET can handle a continuous ...
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0answers
30 views

HC-06 Bluetooth low power mode?

I'm currently using the HC-06 BT module and am trying to figure out if there's a low power mode available. I've found documentation online that say's there is a sleep mode but says nothing about how ...
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votes
4answers
75 views

30A power connector

I've never really used power connectors before. I am working on a project and saw there are power connectors in it. We had some issues and changed the manufactured power connector to a 30A power ...
6
votes
5answers
2k views

What happens if a 240V appliance is connected in a 120V AC power supply?

I know that putting 240V through an appliance rated at only 120V would almost certainly damage it. But what if I connect an appliance rated for 240V into a 120V AC socket? Apart from degradation in ...
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votes
1answer
88 views

Why so many capacitors in design?

I was looking the schematic for programming a standalone AVR chip. I am curious why we need so many capacitors. As far as i know, i know we need one capacitor on the power supply. I don't remember ...
0
votes
1answer
81 views

How does a true sinewave inverter work?

I am an Electrical Engineering student, and when we were taught about inverters (at a power electronics course) we studied inverters using Sinusoidal Pulse Width Modulation. My question is do the ...
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1answer
65 views

Different power sources for pcb

I have a project with arduino. Most devices are powered by the arduinos 3.3V source. But a gsm modem with 5V input and high current consumption cannot be connected with the arduino, because the ...
0
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0answers
40 views

How can I use a 9v chaser board to run LED strips

a few years ago I bought an LED sequencer circuit board kit. Once assembled you can adjust the pace and the brightness with 2 POTs of up to (I think) 8 LEDs. this board runs off of a 9v battery and ...
0
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2answers
29 views

linear actuator power supply and remote or switch

this will be my first DIY project involving electricity so i want to make sure i buy the correct components. i'm purchasing a used telescoping column (aluminum and steel, 4000n) that has two actuators ...
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4answers
89 views

MiniQuadcopter ESC connection

I have a picture here, sorry if it's ugly .. but let's think, they are my ESCs for my mini-quadcopter. My mini quadcopter is 3d printed, and as much as possible, I don't want to use bullet connectors ...
2
votes
1answer
50 views

Measuring precisely the efficency of a power converter

I am trying to measure the efficiency of a DC/DC boost-converter in several operating points as precisely as possible. Right now I am measuring my input-voltage and output-voltage with a multimeter, ...
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vote
1answer
84 views

Understanding a power source's internal resistance?

I have a mechanical system that requires a certain amount of electrical power. Now, when I calculated everything I did not include the internal resistance. For example: I calculated that the ...
2
votes
2answers
207 views

What is a good power electronics textbook?

I really want to learn as much as I can about power electronics, switching mode power supplies, and overall analog design. Unfortunately my universities computer engineering program is still ...
4
votes
3answers
346 views

Smaller footprint for capacitors

I'm (again) placing bypass capacitors around an FPGA, and can't seem to get to a sane solution, given that I have all the pins assigned, and the supply pins are right in the middle of the I/O pins. ...
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votes
1answer
65 views

What is the meaning of 1.5 ton in air conditioner specifications? [closed]

I'm interested in calculating amount of power consumed in an hour. Does 1.5 ton means 1500kWh?
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1answer
43 views

Can a 2W supply power the Relays

I'm designing my first circuit with 2 relays JQX-15F / 005-1Z1 NO20A/NC10A 240VAC(datasheet, probably the SPDT variant) and a 2W ...
2
votes
1answer
58 views

Catch diodes in switch mode power

I am wondering about catch diodes in the context of switching power supplies. I have read all the books that are the norm in designing a SMPS, but all of them don't or barely touch the subject. My ...
0
votes
0answers
23 views

Measuring power consumption of cache memories?

Is there any practical method to only measure the power consumption of combined cache memory. I am intereted in measuring the power conumption overhead when replacing blocks, and or filling the cache ...
0
votes
6answers
77 views

How do I figure out the exact voltage and current needed for a part?

Whenever I look for parts in my local electronics store, I come across parts(e.g a speaker), that have just a power rating stated(e.g 2W). While I know how to calculate power,voltage, resistance etc, ...
0
votes
3answers
130 views

How is Ground in a Power Supply made?

I've been using different power supplies for 6 years. But, I'm unable to understand how we make ground in a Power supply? Or from where does this ground come? Or from where does this reference ground ...
0
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1answer
57 views

Power Supply with Short Circuit Protection

a Power Supply with Short Circuit Protection that Automatically turn Off when Shorted and automatic resumes its function if not shorted without using any switches. thus anyone know how to build this? ...
0
votes
1answer
93 views

Can I test a USB port with a multimeter? [closed]

After a recent thunderstorm (Derecho), we had a power outage. After power restored, I noticed my desktop's USB ports (and a PS/2 port) were not responding, even at a BIOS level. Tried a known good ...
0
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1answer
54 views

Question on Harmonics and Power factor

I need help with the above circuit. I first need to calculate the voltage and current distortion. I calculate this as 8.75%(voltage) and 5.7% (current). I then need to find the displacement power ...