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

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0
votes
1answer
19 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
28 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
-1
votes
1answer
65 views

Strange sound in speakers when the refridgerator goes standby [on hold]

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
71 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
votes
0answers
31 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
3answers
87 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
votes
2answers
80 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 ...
9
votes
4answers
817 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. ...
1
vote
1answer
30 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 ...
0
votes
3answers
147 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
59 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 ...
0
votes
0answers
27 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 ...
-1
votes
4answers
74 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 ...
-2
votes
1answer
87 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
77 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 ...
0
votes
1answer
64 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
votes
0answers
37 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
votes
2answers
27 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 ...
1
vote
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, ...
1
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
196 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
345 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. ...
-2
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?
-1
votes
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
56 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
22 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
76 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
129 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
votes
1answer
56 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
89 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
votes
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 ...
0
votes
1answer
91 views

AN7149N -based power amp usage

I have assembled AN7149N-based power amplifier according to the datasheet, but it shows no signs of life. The only changes I made were 2,7 ohm resistor instead on 2,2 ohm one, and 1000uF capacitor ...
10
votes
6answers
2k views

What happens to excess energy fed into the power grid?

The closest question to this is Linear useage of excess power generation. I'm no engineer so I may not be able to phrase this correctly and would appreciate an answer which assumes minimal ...
0
votes
2answers
41 views

Finding the Average Power Loss in a Series RL Circuit

Question : A current \$I=3\sin(400t)\$ amperes in a series RL circuit in which \$L=1mH\$ and \$R=100Ω\$. What is the average power loss? Answer : $$ APL = 450 \space W $$ My Steps : ...
0
votes
1answer
55 views

Connect two boards together after removing Screw Terminals

An adapter board (to a card edge connector like PCI Express x1) is needed to be designed to for the breakout board below. This should involve replacing the board's screw terminals with some male ...
3
votes
1answer
71 views

Arduino Battery Over-Discharge Protection (O-DP)

I am getting an Arduino Uno soon, and am planning to run off a 8-cell NiMH battery pack (through the power jack). Assuming a .9V cut-off per cell, that'll mean a 7.2 cut-off voltage. How would I wire ...
1
vote
2answers
102 views

Low profile capacitor

I am trying to make a 24VAC to 5VDC converter. My constraint is to keep the height of the entire power module to as small as possible (ideally < 5mm) I have the buck converter design with the ...
0
votes
0answers
38 views

How to test a 3055 with a multimeter?

there have been several good tutorials on this on YouTube. However, I hear about impedances in OHMS. I have measured every possible direction on my 3055 and found 550ohms between emitter and base ...
0
votes
3answers
88 views

How to determine wattages on an applications note schematic?

Specifically, I refer to Fig 18 on Page 14 of this datasheet for dual supplies. Really nice, really "simple" to use 2x40W power amp I want to try out. Unfortunately, I'm a newbie and their schematic ...
3
votes
2answers
136 views

Power origin and power planes placement on PCB

Although there are many similar questions to this one, I wish to get your attention to this specific board layout. The main power on the board will be 5V, and one of the layers is dedicated for ...
0
votes
1answer
88 views

What is the difference between peak-power, average power and true RMS power in RF measurement?

What difference between peak-power, average power and true RMS power in RF measurement? I have read a peak-power measurement can calculate average power measurement also. Does any of these needs ...
0
votes
2answers
83 views

What power is measured by a spectrum analyzer?

Is the signal level that is shown in a spectrum analyzer power of the signal being measured. If yes then what power is it: average power, true power or peak power? Also when using a power meter for ...
0
votes
1answer
77 views

Human Powered Bicycle Lighting System: Is this feasible for an enthusiast?

So, I was doing some reviewing over on bicycles stack exchange, and I realized the Cygolite Metro line of reusable chargers would fit my budget - AND be USB rechargeable! Alas, I've been told ...
2
votes
1answer
124 views

How exactly does a capacitor discharge its charge?

When an empty (discharged) capacitor is connected to a battery, it slowly charges up as one plate fills up with electrons, while the other plate has electrons drawn away from it towards the positive ...
0
votes
2answers
79 views

Convert DC generator to variable AC

Is there a way to convert a DC generator signal to AC and be able to control the frequency and current? Ultimately, I would like to use this signal to measure the impedance of a battery.
2
votes
1answer
41 views

Amount of output current needed by voltage regulator?

I am trying to choose a voltage regulator. One of the metrics I keep seeing is output current, e.g. "Output current up to 800 mA". Does that mean the sum of current that the rest of my circuit ...
2
votes
1answer
38 views

Raspberry Pi and USB modem - can I connect it like this?

As some of you know - Raspberry Pi has only 100mA available on USB ports. I want to connect USB modem (that takes > 500mA sometimes) to my Raspberry without powered USB hub. I have: Raspberry Pi ...
2
votes
1answer
53 views

Multiple (>2) voltage sources

While working on a schematic for a small development board, I was curious how much work it would be to support an external voltage source (ie. bench-top power supply) in addition to the ICSP header ...