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
29 views

Soft Power reset by microcontroller

I want to design a circuit such that the microcontroller can toggle a GPIO pin and shut the whole system (including microcontroller itself) down and then after a short period of time the power should ...
0
votes
1answer
18 views

High power led driver for COB leds

I bought some chinese COB 100W Led lamps from Ebay and I was wondering what would be the most efficient way to power them. Led specifications: 24vDC 4.2A I want to use 4 leds in total, so that makes ...
0
votes
2answers
22 views

0-5V supply to control brightness of BWTek spectroscopy light source

I recently installed a BWTek BPS101 tungsten halogen light source and would like to take advantage of the builtin support for manipulating the operating current (changing the brightness) via an ...
-4
votes
0answers
21 views

what value should i use for 6cells li-ion cells to get output power of 11.1v and 4.4ah [on hold]

what value of a single cell should i use to connect 6 lithium-ion cell to get power output of 11.1V and 4.4ah
0
votes
2answers
55 views

Voltage and Amperage in relays

i have a relayset for Arduino where i find these numbers on each relay: 10A-30VDC 10-28VDC Now, id like to connect that relayset with external devices that run 12V and all the way up to 35A. I was ...
0
votes
2answers
46 views

Choosing Diodes for 3-Phase Rectifier

I'm building a rectifier to rectify a 3-phase signal for part of a school project, so I'm not working at these power levels without help and supervision. This seems to be an appropriate circuit as ...
1
vote
0answers
25 views

Determine active and reactive power from voltage and current over time in a three phase motor

How does one calculate active and reactive power from a set of data containing voltage-time and current-time pairs if the waves are not sinusoidal? I understand that apparent power in an induction ...
1
vote
1answer
59 views

High Side P Channel MOSFET damaged after turn off

The circuit below is a power switch controlled by a push button. Basically, the switch (Q1) is controlled by a On/Off IC controller. During testing on the real circuit, a DC Electronic Load is ...
-2
votes
1answer
62 views

Does order matter when it comes to AC power?

Is there anything about electricity or the electrical design of AC power strips that dictates in what order the devices should be plugged in? When I say, "in what order", I am referring to the ...
1
vote
2answers
101 views

Designing PCB with Multiple power supplies

This is my first REAL project and i need some help. I'm working on a project where I am trying to design a PCB for controlling the environment inside an enclosed cabinet to grow a tomato plant using ...
3
votes
2answers
41 views

Difference between Quiescent Current & Shutdown current?

What is the difference between Quiescent current & shut down current. I have searched a lot but didn't find valid answer. As per as my knowledge Quiescent current is the small current which flows ...
0
votes
1answer
28 views

Linear and Switched-Mode Supply Common Shared

We have a mixed mode PCB system with both digital and analogue systems. Due to high speed they all share the same ground on the PCB, but use logical spatial separation to control noise. SO PCB input ...
0
votes
1answer
47 views

Load sensing switch

I made the circuit here to automatically switch on my workshop dust extractor when I use a power tool. It works fine when used with a drill press or router. However with a Dremel 4000 it only switches ...
0
votes
1answer
26 views

Auto electricity power switcher for two different power sources [closed]

I had two different power sources at home, one is national and the other is the private from a big Generator. I want to connect these power sources so that when both power available, one of them ...
0
votes
1answer
49 views

How can I make the power amplifier stage for this audio amplifier?

How can I implement a Power Amplifier stage for powering an 8 ohm load? I tried making an AB amplifier, but either it doesn't work or I'm just not able to make one. The output of the third op-amp is a ...
-3
votes
3answers
43 views

Power on a three-phase system

Given a balanced three-phase voltage source and unbalanced loads connected in wye whose individual apparent power dissipation and power factor are given, find the the line currents. What is your ...
-3
votes
0answers
32 views

Newton Raphson Method Load Flow Solution Failure Causes [closed]

Newton-Raphson method is used to solve power flow problems. When does this method fail? WHile solving normal single variable non-linear equations, this method fails when the initial guesss made is a ...
2
votes
1answer
43 views

Estimating power usage of idle motor

I would like to calculate the power usage of an idle motor. The motor drives state a power usage of approx 8-10% of full load. Would it simply be the case of taking 8-10% of the motor's power rating ...
0
votes
0answers
45 views

Wireless powered power line robot

I'm trying to make a small robot with a camera that can run on a hanging wire outdoors. I've been thinking of ways to power it such that I would not need to pull a tether around, need to recharge ...
1
vote
1answer
55 views

How should I wire up ground when using an ATX power supply to power an Arduino and several LED strips which in return are controlled by the Arduino?

Forgive me if this seems like a basic question but I want to make sure I wire these things up correctly. Currently, I have several LED strips that I am controlling with an Arduino and they are ...
0
votes
0answers
25 views

Using ~24V SMPS or 12V SMPS in series vs. two 12v lead acid battery to power sine wave APC UPS for custom audio rack 230v/120v clean power supply [closed]

---The context--- I live in India (230V/50Hz), i need to build a road case rack with a power supply that will be placed in the rack and can provide clean power to various audio/recording equipment ...
0
votes
2answers
40 views

PWM Switch High Voltage?

I want to pwm-switch neon bulbs. The powersupply delivers about 220V DC. And i have to switch the bulbs in the "positive" section, so this means PNP, i cant switch them NPN because a NPN Transistor ...
0
votes
0answers
24 views

What specs of power supply should I get for an IR controller for RGB 5050 LED strip?

Here's the story: Bought an LED strip kit (including 5M reel (150x5050 LEDs, rated at 36W), an IR controller, 12V, 2A AC-DC power adapter and a controller). The power supply failed after a few hours, ...
0
votes
2answers
109 views

9 Amps on Ethernet?

I already did my search but I found nothing to confirm it. I have a PCB and I want to connect a jumper that can carry up to 9 Amps. I tried a zero ohm resistance but it melted so I want to use an ...
0
votes
0answers
52 views

Is MAX7219 good for driving a matrix of motors?

In our project we wanted to drive a matrix of motors. We're trying to drive a series of motor-vibrators with an Arduino to create a kind of a tactile feedback grid/screen that will be placed on a ...
0
votes
0answers
30 views

Will a ThunderBolt Connection, Power an iPad Retina Display?

I like this kit from Adafruit but I was wondering if I could do away with the external power and use the power coming from the ThunderBolt connector to power the display and all other electronics on ...
2
votes
1answer
45 views

Taking into account power factor when calculating energy savings

I am attempting to calculate the energy savings of a fan motor after a new runner and inlet cone was installed which claimed to improve fan efficiency. I have logged amp draw before and after the ...
-2
votes
0answers
23 views

PMIC (power management) to detect/monitor USB battery as main power source [+Android Programming]

This question is also on StackOverflow as it involves software as well as EE. I have a micro-computer (custom board) with an SoC (Rockchip rk3288) and it's PMIC (Active-Semi ACT8846) which are by ...
1
vote
1answer
44 views

Transformerless stabilized power supply for isolation amp

I'm building a circuit similar to this: https://courses.cit.cornell.edu/ee476/FinalProjects/s2008/cj72_xg37/cj72_xg37/ (voltage and current sensing of a 230V line) I'm using two HCPL-7520 isolation ...
3
votes
3answers
238 views

Circuit providing output?

What does it mean for a circuit to provide an output power of say 1000W? Is "circuit providing power" referring to the battery supplying energy to the external circuit, or is it referring to the power ...
0
votes
1answer
71 views

PowerBank 2600mah

I got a PowerBank (Power Bank A5 Classic 2600mAh) that claims 2600mAh and for some reason it doesn't charge my phone conmpletely (my phone has a battery of 2000mAh and it only charges 45% of it). It ...
0
votes
2answers
103 views

What is the maximum physical current that can pass through a standard USB cable?

I am looking at hi-jacking an USB cable to supply to supply > 2.1A to the target. What is the physical current limitations of a standard USB cable?
0
votes
3answers
92 views

What's the purpose of the diode in this selectable supply voltage circuit part

I'm looking at the power supply part of the schematic of SparkFun's Pro Micro Arduino board, which has a jumper to enable or disable a voltage regulator to select between running the board at 3.3V or ...
1
vote
2answers
92 views

How to calculate rise time of linear regulator

Given a standard LDO with no soft start, that provides power to a bunch of decoupling capacitors, and a single chip. How do you calculate the rise time of the output rail ahead of time? Is it based ...
1
vote
1answer
63 views

How to use common mode choke inductors? (differential vs common mode)

I have yet to undestrand exactly how to use common mode chokes inductors, according to the datasheet they have 2 operation modes like in the picture common mode and differential mode, however im ...
0
votes
1answer
70 views

How to select power (between USB and battery)?

I'm hoping to power my device with a 3.7V (2x 18650) rechargeable battery which can be recharged within the device using USB (like in a phone, laptop, etc.). I believe some kind of power selector is ...
0
votes
0answers
25 views

36V Backup battery switching

First let me say thanks, and reading through history,there are a lot of smart people on here and hope answer does not go over my head. I have family member that has started a Wireless Internet ...
-1
votes
0answers
64 views

How can I charge an 18V drill battery off of a 12v solar system

I have a small solar setup that runs on 12v. I'm interested in charging my 18V drill battery. I do have a power inverter, so I can plug the drill charger into the power inverter, but my concern is ...
4
votes
3answers
251 views

What does it mean for reactive power to be delivered / consumed?

Real power makes sense since there is actual consumption, but regarding reactive power; what is consumed / delivered? And how does the circuit change once this happens?
0
votes
1answer
45 views

Changing Motor Gearboxes to Reduce Current

I am currently using two 12V CIM Motor (Spec Sheet: http://content.vexrobotics.com/docs/217-2000-CIM-motor-specs.pdf) with a gearbox at a 49:1 ratio. I have a LiFePO4 battery that is rated at a ...
1
vote
2answers
193 views

How do residential analog and smart meters meassure power?

Im building my own digital meter in order to upload the data to a sql database, up to now i know that there are several parameters being meassured into a digital wattmeter: volts, current, apparent ...
0
votes
0answers
31 views

Power MOSFET 27N3LH5 for SMT design

I want change existing through-hole type PCB design to SMT design. The existing design use Power MOSFET 27N3LH5 in TO-220(DIP) package and with Heat Sinks in output channels. The SMD version of ...
1
vote
2answers
66 views

Average alternating power

"For each of the values calculate P and Q" (average) V = 250 \$\cos (\omega t +45)\$ I = 4 \$\cos (\omega t -30)\$ The way I would try solving this would be by converting to phasors, taking the ...
0
votes
0answers
25 views

How to calculate data in PSS/E and export it to Excel?

I am using an IEEE 39 bus system for my purpose about load shedding. I want to calculate some data after disturbance like voltage(PU), the rate of change of frequency, Ymatrix, inertia_constants(H), ...
0
votes
0answers
78 views

Transformerless Power Supply High Current

Is there any way for Transformerless Power Supply to output a High Current like 10A to 15A at 12V to 24V. I found highest of 500mA current output for Transformerless Capacitor Power Supply. I wanna ...
0
votes
1answer
28 views

Low Output from MIC5205 LDO Reg

I have a PCB that's designed to output 3.3V from a 5V source. The 5V source I'm currently using sources several amps (3A), though I only need about 100mA. I based the schematic on "Ultra-Low-Noise ...
-1
votes
2answers
61 views

How many items can be connected to a single power supply? [duplicate]

I have a single 12V 2A power supply which is powering 4 CCTV cameras which require a 12V 1A power supply each in addition to an illuminator lamp which requires 12V 2A supply. At the moment everything ...
2
votes
0answers
56 views

Directional Coupling at kHz Frequencies

I want to precisely measure the forward and reverse power on a high-voltage power supply that operates from 10-100kHz, at power levels on the order of 20W. To do this, I need to make or buy a ...
1
vote
2answers
42 views

When are Avalanche-Rated MOSFETs Necessary?

Why do we care about avalanche rating for power MOSFETs in circuits that exhibit inductive kick (flyback converters, motor drives, etc.)? I understand the basic destructive mechanisms behind ...
0
votes
2answers
106 views

Why is distribution voltage 480V but equipment is usually only rated for 460V?

In the US, distribution voltage is usually 480V. However, most industrial equipment is only rated for 460V. Why is this the case?