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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38 views

How to distribute power to multiple devices on a PCB

I am new to hobby level PCB's, but looking at taking my projects to the next step moving from breadboard. The part I do not know how to do, or see on tutorials is how do I take a single 5V line (or ...
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1answer
27 views

Why PU currents are equal to PU powers with DCPF assumptions?

Can someone explain to me why PU currents are equal to PU powers with DC Power Flow (DCPF) assumptions? I tried to find something on google but I didn't find anything. :(
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Low power USB C power supply

I am searching for a tiny board to that accepts an usb-c cable and outputs 5v. To my understanding, for the few hundred milliamps two 5k1 resistors on the board would suffice. PD is not needed. I ...
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0answers
43 views

MAXIMUM POWER GENERATED BY A CIRCUIT [closed]

This question deals with the use of the venin theorem to find the maximum power generated by the circuit which consists of a load resistor, power source and a current source.
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39 views

Calculate Power Dissipation of an IC

I am trying to calculate power dissipation of the IC for thermal analysis of the PCB. I have calculated the power consumption but not sure which current values to be considered for calculating power ...
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0answers
62 views

What is the optimal circuit to supply 12v and 5v (for microcontroller)? [closed]

I need a good circuit to supply 12v (to power relays and LEDs) and 5v (for microcontroller). Can someone help me with a schematic? The 12v and 5v output comes from an input of 220v mains with an ...
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1answer
47 views

Confused with the formula for Power Factor Correction

The formula provided in my lecture notes: $$C=\frac{Q_c}{\omega \:V_{RMS}^{\:2}}$$ Where $$Q_c=Q_{old}-Q_{new}=P\left(tan\left(\theta _{old}\right)-tan\left(\theta _{new}\:\right)\right)$$ Such that \$...
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1answer
39 views

Automatic power switching, grounds not connected

I'm currently working on a project that requires a 24V DC input. That is no problem, as I have that power supply available. However, the project should also remain working when the supply fails or ...
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1answer
34 views

EMC filter in DC-DC converter cascade

I'm designing a power supply stage and I have the cascade of multiple DC-DC converters. Each DC-DC converter has an EMC filter. The first DC-DC converter requires a capacitor between Vout and GND C1 = ...
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3answers
52 views

Control voltage to heat resistor using PID

I have a question about PIDs. I have a 2.2 kW heat resistor powered from 220 Vac. I would like to control the resistor using PID. As I can see the most PID based control systems are using a Solid ...
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2answers
69 views

Is unplugging computer power cable from PSU the same as electricity outage?

I am not sure if they are the same, but something puzzling just happened. My dell precision workstation 2007 has been fine ever since, with many, many power outages over the years. But there is a time ...
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1answer
21 views

Why do we use PQ and PV buses when solving a power flow equation?

It seems like it would be much easier to just use the admittance matrix and measured voltages to find all the currents and then just use that to get all the power flows. Why not this over going ...
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24 views

Solar Panel Simulation Circuit working, LT-SPICE

I am here again with the same circuit but this time with no errors thankfully. circuit is working but i can not understand the working of circuit. I am not getting why in the single cell's schematic , ...
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4answers
2k views

Determining if mystery PCB with barrel jack power connector is center positive or center negative

I lost the power adapter to the module used to drive a LIDAR sensor I have. I am planning to make a new adapter but one problem I am running into is that I can't figure out if the module's PCB sources ...
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0answers
37 views

Modeling one Current limiting cuircuit with two BJT

I trying to better understand one article related to current limiting with two BJT. The link is here: https://www.planetanalog.com/seemingly-simple-circuits-user-proof-external-supplies-circuit-3-the-...
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Do different Line-Ground voltages on a 240v L-L PSU fed from a 3 Phase High Leg Delta system pose a problem?

I'd like to know if there are any negatives related to powering an ASIC miner PSU at 240V, 2 hots and a ground (C13 plug), from a three phase, center-tapped, high-leg delta system, when the line to ...
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0answers
29 views

DC Step Down 40-80V to 12-24V wth 10A load [closed]

Looking for an IC or design that has an input of 40-80V DC with an adjustable output of 12-24V that can handle a 10a load no matter what voltage it is outputting. The voltage supply is a 12s lipo ...
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1answer
53 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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4answers
65 views

Source selection Circuit

I am doing a project, in which there are two dc source a) 48V_ DC b) 48V_Reg to power the board. If either of two is present, that power source will power the board. If two power source is also ...
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2answers
41 views

Power input connector for power distribution board

I have been looking at several different power distribution module designs and the all seems to use a large bolt for the main power input. I am curious what these connectors are called and how they ...
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2answers
113 views

What is the phenomena behind this DC generator plot?

There is a DC generator to be calibrated with its plot below. On the X-axis there is the ratio between the power of the generator/ nominal power of the generator. On the Y-axis there is the efficiency ...
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4answers
824 views

How do I determine whether a switch can handle the power/current in a circuit?

I have a switch that has "3A 250VAC" and "5A 125VAC" printed on it, which I imagine are ratings of what the switch can handle, but my understanding that 3A at 250V would be 750W ...
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3answers
105 views

How is this 22 AWG cable rated 4 Amps?

I found the cable (1533576 - Actuator/Sensor-Cable, M12 Socket - Open End Connector, 2m, 4A, 250V, Phoenix Contact) here that is claimed to handle 4 A and is then written that it has a 22 AWS cross ...
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2answers
47 views

Maximum length of WS2815 strips

I have six 12V WS2815 that I would like to connect in a series and control with WLED running on an nodeMCU board. I have the 5m x 30LED/m = 150 LED strips. I'm struggling to figure out the proper way ...
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0answers
26 views
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Soft power off with delay after flipping physical switch

I have a microPC (the Jetson Nano, 10 W) that cannot handle a sudden power loss. However, the casing I need to design it for only has a latching switch for powering on and off. I need to design a ...
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11answers
3k views

Why are cables rated for current not power?

I was wondering, since resistors are rated for power, not current (so one can blow them with both overcurrent or overvoltage), then why are cables rated only for current? Aren't resistors just stacked ...
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0answers
63 views

Basic circuit power dissipation

if the question lies "Which unit uses the most power? How much power does that unit use?" Does that mean how much power is dissipated through heat or is it about the voltage/current sources ...
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0answers
21 views

Supplementing battery pack + buck converter to handle peak draw momentarily

I have a battery pack at ~9VDC wired to a buck converter which steps down the voltage to 5VDC to power an electronic device. The problem is that it sometimes supplies enough current on the device ...
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0answers
52 views

Can I power my TV with 12V without an inverter [closed]

I was wondering if I can rebuild my TV to use a 12V power supply? I opened it and found the power supply below. It has connectors marked "12V", "24V", "5V". I guess I can ...
2
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1answer
49 views

LT-spice-Simulation model for PV panel

I am totally new to LT-spice and i want to simulate a model for PV panel. i followed a youtube video as itas, but my circuit is not working. i have no idea about the errors it's showing. please help. ...
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3answers
115 views

LC power filter, big L or big C?

I was reading a datasheet for a Murata DC-DC converter Murata DC-DC converter. It has the following LC filter recommendation to reduce output ripple: As the output voltage of the DC-DC converter goes ...
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2answers
78 views

How to design Zener diode for a kickback voltage protection of motor?

Vcc: 34 VDC Motor load current: 5 A How to design motor kickback voltage protection of Zener diode?
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2answers
67 views

SMPS noise suppression

I am looking into fitting ferrites to my SMPS power supplies output leads (wall warts.) I have been getting some strange noises on my valve stereo amplifier since using a couple of LV DC PSUs as ...
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2answers
91 views

How to show that it is not possible to exceed the power rating of a 1/4 watt resistor of resistance greater than 1k?

I am currently studying The Art of Electronics, third edition, by Horowitz and Hill. Exercise 1.5 says the following: C. Power in resistors The power dissipated by a resistor (or any other device) is ...
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1answer
56 views

Some segments not working on 7 segment multi led digital clock

I have this old homemade digital clock which i'm trying to revive. It has sentimental value as it was built by my dad in his youth. The problem is 2 of the segments only sometimes light up on the ...
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1answer
53 views

Converting an electrical schematic into a physical panel layout

I'm an undergrad researching physics, my job has been to make this electrical schematic, can I get some help figuring out the physical layout? I've basically self-taught myself enough of solidworks ...
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1answer
96 views

Connection problems or burned chip?

I am assembling a board for a wireless charger based on this evaluation module (see here) I own a preheat bed, a hot air gun and a quality soldering iron. I am afraid that after soldering the chip and ...
3
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1answer
71 views

Wattage of LED based growth light not consistent with LED usage

I have ordered a growth light for my plants. Only later did I realize that it said its a 2kW light, which seemed quite excessive as it is only the size of a small keyboard and not that densely ...
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0answers
36 views

PC Board/Power Transistor heat dissipation

I am attempting a repair on a failed Sansui 881 Receiver / There's an obvious problem on the power supply board where the heat sink of a power transistor has 'legs' that are soldered to the PC Board, ...
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0answers
31 views

A question about power transformer power rating on a diagram

As a part of the one-line diagram, a power transformer is shown as below: Here what I understand is that 400/132kV means 400V is the primary nominal voltage and 132kV is the secondary nominal voltage....
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3answers
119 views

Why is power gain a meaningful quantity at all?

I'm quite confused at a very basic concept: power gain. An amplifier can be said to have a power gain of x decibels. The gain of an amp in decibels is never voltage or current, it is always power. But ...
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2answers
34 views

Combining DC power input from multiple erratic sources (solar / wind turbine)

My understanding level: I'm reasonably familiar with simple electrics and electronics - volts, amps, watts, simple circuits etc. I'm thinking my question is either really simple, or complicated - but ...
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0answers
13 views

Transformer Power Rating for CCFL Inverter

I'm trying to design an CCFL inverter using the UCCx972/3 but I am a bit confused about the power rating for the transformer The lamp I'm using has the same operating voltage and striking voltage of ...
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1answer
31 views

Appropriate resistor values for 5V LNK low-power supply in CC mode

UPDATE: QUESTION SOLVED/CLARIFIED. PLEASE REFER TO THE LAST "HAND MADE" SCHEMATIC IN THE SERIES OF PICTURES BELOW, AND READ MY FINAL "SOLUTION". Original question: * I wonder what ...
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0answers
22 views

What is the name / Part Number for PCIE 6+2 Power Connectors (Specifically the +2 connector without a retention clip)

This is the part I'm trying to find: I can find the 6 pin connector (I think), but I can't seem to find the +2 pin connector. I'm attempting to make some cable assemblies for a weird but fun project ...
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0answers
38 views

Powering arduino nano efficiently with 18650 batteries

I need to implement a UPS for my arduino nano project (using VIN) in case there's a power outage. I tried a single 18650 (NCR18650B), a battery charge module and a step-up voltage regulator but the ...
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1answer
34 views

Why does this magnetic relay max DC voltage rating is much less than its max AC voltage rating?

Below is a specifications of this magnetic relay: For AC and DC the max switching current is given same as 10A. On the other hand, max switching voltage for DC is drastically lower than its AC ...
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1answer
53 views

Understanding Per Unit System

I am having issues understanding the Per-Unit System calculation. I don't come from an exact power engineering background so I hope my question is not too stupid. For the calculation of base ...
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0answers
29 views

Need spec sheet on Cherokee International smps SP671-Y01A

I am trying to fix a power supply SP671-Y01A made by Cherokee International. It is a 24volt supply. If anybody has a spec sheet and or tell me the output enable pins that would be awesome. There is ...
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2answers
77 views

General purpose diode between 2 power rails

I am looking at a schematic where there is a general purpose diode connected between the positive side of a 5V DC rail to the positive side of a 12 V DC rail. The circuit is powered by a power supply ...

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