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
2answers
35 views

How to select value of resistor to dicharge a capacitor

how to set the value of bleeder resistor to dicharge 10KV capacitor which has capacitance value of 5micro farad
-5
votes
0answers
47 views

“Battery Ground” message on the annunciator [on hold]

I am getting "Battery Ground" message on the annunciator. Where would be the short? All the connections are checked , and they are fine.
0
votes
2answers
49 views

Best place for a switch when using an always connected power adapter

I recently bought this: http://smile.amazon.com/gp/product/B00II1MN5I and am planning on using it for under cabinet lighting in the kitchen. ...
-2
votes
0answers
40 views

Can I power my multi-effect processor with a nintendo adapter? [duplicate]

I've bought a multi-effect processor called "ZOOM PLAYER 3030". The vendor gave me the wrong AC adapter, so I can't use it. He told me that he will give me the wright adapter if I visit him next ...
1
vote
1answer
60 views

Single phase energy meter measurement

In a single phase meter measurement, the power is being measured by using the instantaneous power which is p(t) = v(t) * i(t). But as we need to sample the voltage and current to get the power, hence ...
0
votes
1answer
29 views

Is it advisable to try to discover a place to make a ground connection on a board with a separate AC power supply?

I am building a device consisting of a microcontroller (an Arduino mini) attached to various output devices, which will be triggered using a wireless doorbell receiver. The receiver is a single board ...
0
votes
2answers
36 views

PMOS, NMOS length width concept for low power circuit

Why for low power consumption width of NMOS taken same as length of feature and Width of PMOS taken as 2.5 times width of NMOS ? e.g for feature size 180n width of NMOS 180n and width of PMOS 450n. Is ...
0
votes
2answers
56 views

Is it possible to power an Arduino Uno with a Raspberry Pi?

I have an Arduino Uno and a Raspberry Pi that I'm using to control some LEDs in a computer case. Power is coming from a Molex connector from the computer's PSU. I want to place the Arduino and the Pi ...
0
votes
1answer
44 views

12V battery choices (powered LEDs and piezo buzzer)

I need to power two 12 V LED lights (1W - forward current @ 0.083 A) and a small piezo buzzer all in parallel (unsure about the current, tried to measure it with multimeter, but get nothing...). ...
1
vote
2answers
54 views

On/Off DC power indicator [duplicate]

I am pretty sure that this should be simple but the answer is eluding me. Basically I would like a simple 12V DC circuit that lights one LED (red) when a power switch to a pump is off and would ...
0
votes
0answers
19 views

How to rectify the power line for leakage current based electrical shocks? [duplicate]

In May 2014, I had purchased Samsung LCD TV with two pin mains cord. I used to get electric shock like feeling when I touched the metal body part of it or the HDMI port (any other connected ungrounded ...
2
votes
1answer
94 views

Is it possible to inject USB signals (with power) through Ethernet?

I'm just curious whether it is possible to inject USB through Ethernet in a way like POE does but with the additional data lines USB needs. As per my understanding Ethernet (at least the slower ...
0
votes
4answers
105 views

My thought on the reverse polarity protection

I am now designing a power reverse polarity protection circuit for my system. I found that most methods used for the protection would cause voltage drop in the power path. Even the MOSFET, which has ...
1
vote
3answers
818 views

Doesn't High Voltage Lead to More Power Loss

In India we use electric supply at 230 volts / 50 Hz whereas in US it is 110 V / 60 Hz. Since power loss in an equipment (say resistive heating element) is directly proportional to the voltage, ...
0
votes
1answer
50 views

Explain this line of working when solving for the maximum power of a load resistor

Please, can you explain this line of working from the maximum power transfer theorem: For maximum power dissipation in the load, the condition given below must be satisfied $$\left. ...
1
vote
2answers
45 views

Calculating discharge time of 12V LED light powered by AA batteries

I just want to check up my assumption on power consumption of six 12V LED lights in parallel connection. So I powered it by 6 AA (E91 energizer) batteries. The LED's ideal forward current is 80 mA ...
0
votes
3answers
82 views

How can I make a safe Ni-MH charging station?

I wanted to make a docking station for my robot. My idea was simple - robot drives in, batteries are disconnected, pins that I attach to my Ni-MH charger's electrodes are inserted into battery pack, ...
2
votes
1answer
87 views

Power loss during transmission

I have no background of electrical engineering so if my question sounds stupid then accept my apology in advance. I want to calculate the power loss during the transmission. I am using the simple ...
-3
votes
0answers
50 views

Discharging a 10kV capacitor [closed]

Please help me in designing a circuit to discharge a 10 kilovolt capacitor in PSIM software which works in continuous conduction mode and uses phase shift PWM control strategy to charge this 10 kV ...
0
votes
1answer
118 views

Why are these LEDs listed as 3W when the forward voltage is 2.4V, and forward current is 700mA?

The title of this listing says 3W: http://www.ebay.com/itm/50PCS-3W-RED-80lm-640nm-LED-Plant-Glow-Light-Emitter-with-20mm-star-base-/221518318191?pt=LH_DefaultDomain_0&hash=item3393854a6f But ...
1
vote
0answers
73 views

Insufficient Power when using one power source vs two [duplicate]

So I've been working on a wireless remote relay switch using several components and have struck a break wall. The issue I'm having is that the D0 siginal output triggers the relay but only at short ...
2
votes
2answers
109 views

Check my math: Calculating the size of extension cord needed

I think I've done this right, but I don't trust myself. Will you check my math and see if I'm right about this, or correct my error if I'm wrong? The facts I have a device (A Yamaha Stagepas 400i ...
3
votes
3answers
132 views

Inductor selection for a switching regulator

This is somewhat related to this question, but hopefully a bit broader. I'm selecting components to fill out an lm2734. This regulator will take a 9-12V (11.1V nominal) input down to 5v @ 1A max. ...
0
votes
1answer
61 views

Can a Nordic Semiconductor nRF24L01+ be powered by 5V?

When I look at the nRF24L01+ datasheet, I'm confused by two apparently conflicting details. "1.9 to 3.6V supply range" (page 1, Key Features) 5.25V maximum input voltage Vi (page 12, "absolute ...
2
votes
1answer
149 views

What is the need of Neutral and Phase Metering?

I'm working on a project where I have to implement a metering IC to measure Voltage, Current and Power on 230v power lines. I have to use Atmel's 90E24 single phase metering IC. This IC has two ...
0
votes
0answers
37 views

Rechargable battery solution for Arduino Uno

I am currently working on a project including an NFC Shield and a Bluetooth Shield intend on making the project wireless. My question is; Are there any battery solutions that allow me to ...
0
votes
1answer
54 views

Vehicle-to-grid technology

As I understand, vehicle-to-grid technology is about using the battery of your electric car to give electricity for the microgrid. How would this be useful as we are just moving electricity from place ...
0
votes
3answers
198 views

Tapping energy from high voltage AC transmission lines

The details are hazy as I recollect this from my nipper days.Many, many years ago. “Persons were charged with stealing electricity by placing a large coil, somehow, near high voltage AC transmission ...
1
vote
0answers
33 views

Can I change VCC pin to 3.3V on a 5V Arduino Pro Micro? [migrated]

I'm using a 5V Arduino Pro Micro (schematic). For my project, I'm using the VCC pin to output power to an external device. I need VCC to output 3.3V to the external device. Can I open jumper SJ1 to ...
1
vote
1answer
156 views

Ok, EAGLE eyes… what am I missing here?

Ok, so most of my schematic is completed, and I've cleared all the ERC checks but this one. I don't seem to see what the problem is. all the positive powers are connected using the same (copy paste) ...
0
votes
4answers
237 views

Powering an ATmega328 chip

I am trying to make a printed circuit board for a robot. I would like to make this look as neat as possible, and I would like to have the peripherals like the sensors and other stuff, and the ...
0
votes
3answers
61 views

Large Wires on a Perfboard

I am working on a project on Perfboard which involves controlling a motor that draws about 10A, and I am using 18AWG stranded wire to connect the MOSFET on board to the battery and motor which are off ...
-2
votes
1answer
113 views

Why is the LED of my Illuminated rocker switch always on?

I recently purchased a rocker power switch from RadioShack (103-R13-135B-02R-EV) and it works great. However, even when the switch is off, the small red LED stays on. Is this normal? Won't this ...
0
votes
2answers
64 views

Why increase in resistance of register used in circuit show lesser average power dissipation

I am working on 6 transistor full adder circuit. Red marked resistors (25k) are used to show all pattern of full adder correctly. But it show wired behavior. When I increase resistance from 25k to ...
2
votes
1answer
74 views

Which transformer faults will lead to power outage?

I have year by year data of number of faults in 330 kV power transformers. Faults are of various kinds and there is no additional information about how many of those faults led to power outage. I am ...
0
votes
2answers
114 views

Does Thevenin's theorem apply in power plants?

I know when we analyze a circuit's Thevenin equivalent, the best we can ever get is 50% power transfer to the load. I would assume that this holds true for power plants (source) and the rest of the ...
4
votes
1answer
544 views

Data over a 5V DC power connector

I am looking for a simple way to encode some data over a dc power line. (Probably using a very low cost IC) In my design, I have a port that provides 5V, 200mA for connecting some device, but now I ...
1
vote
1answer
80 views

Power calculation of a transformer using only current and resistance

If I use \$P = I^2R \$ for primary and secondary will that tell me the effective power being dissipated? Uf I divide secondary power by primary power and multiply by 100%, would that tell me the ...
1
vote
2answers
64 views

Problems without ground, Amplifier & Exploding surge protector?

Not sure if this is a common issue, or how to formulate a single question, so please feel free to edit. I'm just trying to understand the situation and don't know where else to turn. I have an ...
0
votes
1answer
52 views

When routing power how is a safe current-carrying wire configuration determined with multiple wires?

I've been looking at a device/power-supply pair I was sent recently for a project. The device specs say it needs 24V and will draw 10A max. The power supply provides 24V @ 9A (14A peak). The power ...
0
votes
1answer
57 views

Inform microcontroller that the analogue circuit is powered up

Basically, I want to pull-down the microcontroller pin if some analogue circuit is powered up. The analogue circuit power is 9V, 1.6A. The idea I have is to use something like IRLZ24N MOSFET, connect ...
3
votes
0answers
81 views

Lithium battery consuming more power on Sleep Mode

I am trying to reduce the power consumption for PIC18F87J11 on sleep mode. The PIC is drawing about .01 mA (6 uA) on sleep mode with Alkaline AAA batteries and other power source, but when I use ...
0
votes
1answer
90 views

Connect a 4-pin connector to power supply

I currently have a fan with a 4-pin connector that I want to power, but I do not have a power supply with a 4 or 8-pin connection. Is it possible to disconnect this connector piece and connect the ...
-1
votes
1answer
57 views

Which Clock Would Run Faster [closed]

I have two identical clocks: one is plugged into 120 VAC @ 60 Hz. The other is running on a 12 volt battery. Which would run faster, and more importantly, WHY? Based on my understanding of a quartz ...
1
vote
1answer
65 views

How does USB 3.0 negotiate power states?

I noticed, in another question, a comment regarding USB power states. I know that USB 2.0 negotiated power by tying the D+ and D- lines to specific voltages but I can't seem to find any information ...
-4
votes
3answers
65 views

Understanding Power Sources and Amperage Ratings [duplicate]

Bunch of questions here, but probably basic for you all. My wall outlet is 120v, 20amps. 1) What makes it 20amps? Where is the resistance applied? What if it was 30amps instead? Where along the ...
1
vote
3answers
124 views

Can the power source for a USB device be different from the data source?

I was wondering if the data source (USB Host) for a USB device has to also deliver the power 5V circuit e.g. data and power need to have a common ground. Or can I connect the data lines to the data ...
8
votes
8answers
400 views

Neophyte question about AC vs. DC (especially for powering a home)

Here in the United States the electricity grid is AC. I have heard that AC allows transmission of power at greater distances with less loss. However, with the advent of solar panels, it would seem ...
2
votes
2answers
125 views

Connecting power source to Arduino's 5V pin

I have an Arduino board connected to a Neopixel Ring. This Ring draws more than 0.5 Ampere, so it needs its own power supply (not drawing power via the Arduino board) I found this schematic that ...
1
vote
2answers
47 views

Two outlets, to power device if either is on

Basically, I have a 120V device I would like to have powered if either/both of two outlets have power. So both could be on, or just one of them. The device itself is typical in that it only has one ...