Questions tagged [power]

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

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50 views

What is the physical meaning of integrating the output characteristic of a MOSFET?

If I integrate the output characteristic of a MOSFET, calculating the surface area under the curve \$I_{ds}\$ - \$V_{ds}\$ at constant \$V_{gs}\$, what will be the physical meaning of the calculated ...
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3answers
67 views

What frequencies are usually used/most efficient for coaxial transmission lines/?

I was researching what frequencies are usually used for coaxial Tx. Most sources just says that at low f the length of the line doesn't matter and vice versa. However, I couldn't find a source that ...
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2answers
66 views

Is the gauge big enough? String Pixel

I think I might need different pixels or an additional power supply. I bought 10 strings of 50 (12mm, 12v) pixels (aka WS2811 12mm 12V LED) to do my first matrix project. It says that is uses 22awg ...
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0answers
37 views

High Power BJT Current mirror

I am trying to find an example of BJT current mirror with high power consumption. Any advice concerning the setup , or an example design will be appreciated.
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1answer
70 views

How can Kill-a-watt show .1A, 12VA, but 0 watts?

I'm trying to verify whether a 10W aquarium heater is failing. It has a safety fuse that renders it permanently inoperable if it overheats by running unsubmerged, which is suspected in this case. My ...
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2answers
26 views

External power supply design - Audio Microphone preamplifier . AC vs DC

Any outstanding pros and cons of transmitting over short distances (1-2 meters) AC vs DC? Details: I wish to move the power transformer from a micpre into a small external enclosure to eliminate hum ...
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1answer
157 views

What is the difference between pulse-skipping mode and burst-mode in power converters?

I have been looking at methods to regulate a resonant converter which switches from full load to zero load at rates anywhere from 100Hz to 100kHz. I am looking online at some journal/conference papers ...
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1answer
111 views

Choosing the right PTC Resettable Fuse for a protection circuit

Power shield protection circuit specs Hello! Iv'e been creating an ESP32 power shield and started designing the protection circuit for the power supply with the following features: Reverse polarity ...
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3answers
52 views

capacitor & voltage source power transfer

When I have a capacitor connected to an AC voltage source, we can get from i=C*dv/dt the current through the capacitor (therefore through the voltage source). Than we can multiply the voltage across ...
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0answers
30 views

UC3845 flyback add a OVP (OVC) protection

I built SMPS based on this schematic: It's working nicely - I recalculated transformer and flyback to 24V, I used EI33 transformer with airgap (put 6 pieces of paper between halves of the core). I ...
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1answer
892 views

What to consider when powering multiple devices in parallel?

Briefly about my background, which might inform the question. I'm currently self-educating myself on some electrical engineering on-the-job. I'm learning from Art of Electronics and some other ...
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2answers
53 views

What type of circuit or component is used to sample RF power?

I'm building a 2-stage RF power amplifier and I would like to measure the RF power at each stage and report it to a microcontroller on the board: ...
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1answer
80 views

three phase inverter design in ltspice

I have designed three phase inverter in ltspice with SPWM technique using mosfet switch. the output voltage at the load is incorrect. could anyone please tell me what is wrong in the simulation to get ...
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0answers
23 views

IGBT modelling from datasheet

how to model igbt from the APT150GN120J datasheet. ...
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0answers
43 views

How to find calories (basically power) from a voltage vs time graph? [closed]

So I have a deadline to hit and I need to find the power from a dataset my team collected. They did not do good data collection and I'm stuck with this graph. https://ibb.co/80rnVFb ...
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3answers
97 views

How to make sense of EIRP?

I've been introduced to the concept of equivalent isotropically radiated power (EIRP) and so far I've used it to calculate RF power density at distance of 100m radiated by a directional antenna with a ...
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2answers
38 views

Power Dissipation of Diode

I have two diode datasheets. Onsemi Vishay In both the datasheets, why is the maximum allowable power dissipation of the diode not provided in the absolute maximum ratings table. Usually, in ...
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4answers
705 views

How to calculate maximum input power on a speaker?

I got into this rabbit hole while trying to replace the speaker wire in my setup. I have speakers with 8 Ω of resistance (Rspeaker) and a maximum input power of 140 Watts, so I wanted wires that would ...
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0answers
22 views

Hot Swappable Battery Circuit with Varying Amperage Demands

I am designing a UAV that requires a hot-swappable battery circuit. The drone has a peak discharge of 50c at a 6s voltage. In order to increase battery capacity, I intend to use higher capacity ...
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1answer
92 views

85W laser array driver circuit

I have an OSRAM 85W 450nnm laser array. It's essentially a large 'chip' with 24 integrated laser diodes (break it down they're approx 3.5W diodes each.) The Chinese source I purchased it from also ...
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3answers
117 views

Why do not we carry energy as DC in dams?

If a wire's DC resistance is less than AC resistance, which it is, why do we carry energy as AC in dams? (high resistance means high loss, why do we carry it with higher losses?) Why don't we carry DC?...
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1answer
84 views

Prototype needs 3 different voltages (3.3, 4.0 and 5)

I have 3 components on my board that have different power requirements. They are as follows: msp430fr2433 needs 3.3V (Active mode) draws 126uA/MHz. Clock freq is 8Mhz, so the draw will be around 1mA. ...
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2answers
58 views

Reverse leakage loss in diode

How can I calculate the reverse leakage loss in both diodes (2 switch half bridge rectifier ) ? I found this equation: \$P_{leak} = (1 + \delta) · I_{rr} · V_{rr}\$. There is no demonstration. Is it ...
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1answer
46 views

Selecting the power source for load using MOSFETs only?

I'm looking for the circuit to automatically switch the load (< 0.5 A) between the main power source (USB) and back-up (battery) without a specialized IC and without the functionality of charging ...
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1answer
83 views

Why do we need to use special versions of voltage regulators on negative rails when the input is isolated from the positive rail? [duplicate]

Take the example of the well-known LM78XX voltage regulators: there is the LM7812, and the LM7912. The latter should be used to generate -12V from, say, -24V whereas the former is used to generate +...
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4answers
294 views

How to connect multiple 0402 leds to an Arduino for a 1:87 model

I want to replicate lighting a 1:87 scale police car with the aid of an Arduino Pro Micro ATmega32U4 powered by a 90mAh 3.7V LiPo which is connected to a TP4056 5V Lipo battery charger which is ...
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6answers
24k views

Does water actually damage or only temporarily disable electronics until drying out?

Does water leave any damage after drying out? If it does, where and how exactly does it? How can it be repaired?
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0answers
37 views

Power suspend supply voltage on USB host controller

I'm trying to use the VL805 USB host controller in a design that I'm working on (datasheet) and I came across pins that have "3.3V suspend power" in their description. What does this mean? ...
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1answer
39 views

Switch to stop battery from discharging step up

I have a problem with this circuit. The circuit works fine with the LDO, Step up and battery management. However, when the step up still remains on when the SHDN is sent to zero. Effectively, I would ...
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1answer
35 views

What is the best/accepted way to charge multiple 18650 batteries in series but by themselves?

I am wondering if I had 4 18650 batteries that I want to run in series, is there a best/accepted way to charge each individual battery? In other words, instead of having to purchase a 16V charger for ...
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1answer
161 views

design for portable pv charging for 97Wh lithium ion battery

The manufacturer of my medical device has provided a Lithium Ion battery with these characteristics: 97 Wh Output 3.75A Input 100-240V, 50-6-Hz, 1.0-1.5A Protection overcharge, overdischarge, exess ...
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0answers
63 views

Buck boost converter question

Working with a buck-boost converter the input voltage is given Vs=100V, output voltage is given Va=-150V, switch frequency is given 50kHz, L=150μH and C=220μF. Given that the inductance works in the ...
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0answers
19 views

How do i implement a dual role power system for my custom PCB, where my usb-c port can act as a source and sink

I currently have a custom PCB design using the PIC16F1937-CN. The custom circuit gives an output voltage via the USB to an external device. I would like to charge my circuit's battery with the same ...
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3answers
104 views

Is a power amplifier able to generate power? Does a power amplifier draw power from a supply?

Is a power amplifier able to generate power? Does a power amplifier draw power from a supply? Does a power amplifier dissipate power itself? If a power amplifier draws power from a supply, does it ...
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7answers
255 views

Frame grounding, data & power - EMI

I'm looking into building some large robotics with (ofcourse) a frame, (shielded) data/communication cables - EtherCAT, and power lines. Now different 'experts', websites and people say all different ...
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1answer
39 views

Capacitor and resistor in parallel in output 19V laptop charger [closed]

I have been studying with my charger and I cannot figure out why it leak ac while also providing DC 19V. When I touch anode and cathod of the charger and checked it, there were no ac current flow. I ...
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0answers
43 views

Wireless Charging For Home Use

I want to be able to charge my home devices, such as my phone, using long-distance wireless energy transmission techniques. The first idea which popped into my mind was a tesla coil. But a 2-second ...
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1answer
117 views

Obtaining data from parallel port without the “phantom power” problem

After making failed circuits in the past, I learned that the cause is that the parallel port was producing "phantom power" (aka powering the circuit). This is because I plugged my circuit into the ...
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2answers
43 views

How generator becomes under excited/ over excited?

I keep reading in power system notes that a generator when under excited/ over excited either absorb/ release reactive power. Question is, what determines these under excitation and over excitation? ...
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0answers
32 views

About oscillations in a time-delayed power system

I'm new here so pls correct me if there's anything inappropriate. For a power system without delay, we can calculate its eigenvalues, where each pair of the complex eigenvalue represents an ...
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0answers
39 views

inductive load in transmission line

In transmission line when I increased my inductive load my receiver voltage(Vr) was increasing instead of decreasing. why is this happening? plz, give thorough explanation if possible.
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1answer
51 views

How long can you power a solenoid? Is heat an acceptable way to check?

I am wondering how long you would expect a standard electromagnetic solenoid like this to be able to be switched on? Any first hand experience would be appreciated. If there is no data on this - is ...
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0answers
36 views

AC-DC converter to drive a dc motor (treadmill)

I would like to fix my treadmill. I have connected a SCR voltage dimmer (WINGONEER AC 220V 4000W) in series with a full-bridge-rectifier (GBPC5006), to the dc motor. When I move the potentiometer, ...
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0answers
33 views

24V power supply Circuit [closed]

Using the same power supply 24V to drive the 2 motors and 9V power supply from battery, what about the 5V input supply, for IC controller, can I draw them from Arduino Board to include GND to be ...
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2answers
609 views

Picking a power supply for a TMC2130 stepper driver and motor

I'm trying to pick a power supply and need a little more guidance before I'm comfortable spending money on one. This site explains how to calculate your figures for power supplies but isn't too ...
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3answers
294 views

Is it possible to decrease the power dissipated in a winding with a constant braking torque?

I have a 4-quadrant current controller which regulates the braking current of a brushed DC motor with a high-inertia load to a constant level, but the motor winding cannot handle the current required ...
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4answers
111 views

Energy conservation when adding braking resistor to H bridge?

This may be a stupid question but I'm missing something fundamental about energy conservation of electrical machines - I am sure I have forgotten something from basic machine theory but I haven't ...
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1answer
29 views

L6-30R with L5-20P Devices

My computer lab just got a power upgrade, now we have 208V/30A with L6-30 receptacles, in addition to what we previously had. I have some leftover rack mounted power distribution units (PDUs) given to ...
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2answers
121 views

Why does rotor of synchoronous generator accelerate during faults?

I don't understand the electrical torque in a generator. Isn't the counter torque related to the armature current in the generator? Why does electrical torque decrease during fault in lines that ...
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1answer
37 views

Problem with Synchronous motor

I hope some one have an answer for me. We have a 2600 HP synch motor driving two generators this feeds a mine winder typical ward leonard system. The synch motor starts up through a korndorf starter ...

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