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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2 answers
40 views

How do I power an STM32 dev board with 9 V properly?

Dev Board: Discovery board with STM32F411VET What is happening in the MCU? I saw the datasheet with the 100-pin chip and and saw it has a bunch of VDD pins and a VBat pin but I'm not sure how the 5 V ...
2 votes
2 answers
30 views

What is an intuitive explanation of using a boost converter for power factor correction?

By theory, a bridge diode and a capacitor bank can convert an AC sine wave into a DC signal, but the source current would appear spikey, having a power factor much smaller than unity. In order to ...
1 vote
2 answers
5k views

Is a desktop PC power supply an inductive or a resistive load?

Our daily computers' (desktop PC, server, or normal laptop, mobile chargers) power supplies: Are those power supplies inductive or resistive loads?
0 votes
1 answer
87 views

How safe would it be to build your own 15 kW, 3-phase generator?

I need to get a petrol/diesel generator for my house with a power rating above 15 kW. It should be a 3-phase generator. The prices of such generators are extremely high. I have a working 2000 CC car ...
0 votes
7 answers
885 views

How to select BLDC motor for high torque applications

For electric vehicle I need to choose BLDC motor. Rated power around 2 to 3kW 48 nominal voltage. I don't need high speed, but would like to have high torque at low rotation speeds. There will be ...
0 votes
2 answers
122 views

Proof of a conjugate property

In power systems, I understand why S=V·I*. However, I am having a hard time understanding why I=S*/V*. Can someone explain, or better yet prove, that I=S*/V*? You don't have to prove it under power ...
7 votes
11 answers
3k views

Easy and cheap way to sink more than 5 A from a power supply

For an experiment I need to check a current sensor but I need to parallel too many resistors to achieve that without damaging the resistors. I don't want to do that. The PSU is 12 VDC, 10 A and I want ...
-1 votes
0 answers
37 views

Switch to battery when the power supply turns off, operate fan for 2 min and then all [closed]

How to switch to battery when the power supply turns off, operate fan for 2 minutes and then all turn off battery power supply?
1 vote
1 answer
50 views

8 LEDs in parallel each having a switch with a constant voltage supply of 12 V

simulate this circuit – Schematic created using CircuitLab I have a question regarding the schematic shown above where I have 8 LEDs connected in parallel, each having a switch. Since the supply ...
1 vote
1 answer
86 views

Battery replacement for 16 VAC

I have a mains power adapter that powers a small model train set. I would like the option to power this off a rechargeable battery, although I'm not sure this is possible, as it uses AC. My current ...
2 votes
1 answer
2k views

Calculating AC Input Power

I'm making an AC to DC power supply that connects to mains. There's an AC to DC converter, buck converter and a smoothing LDO that outputs a DC controlled with pots. I'm verifying the supply, and ...
0 votes
0 answers
43 views

How to run a 12V device with a 5V supply? [duplicate]

I have a fairly low-power 12 V device which I'd like to power from a 5 V Li-po power pack. Assuming my 5 V source has enough total power, is there a simple converter I can connect between the device ...
1 vote
3 answers
106 views

20 W 400 kHz -1 MHz power amplifier

I'm designing a power amplifier for a piezoceramic transducer with these specifications: 20 W and 400 kHz - 1 MHz bandwidth. I do not have much experience with power amplifiers, so my design must be ...
5 votes
2 answers
667 views

How do modern CPU manufacturers determine the suitable base clock and the associated power?

Modern CPUs have very smart boosting strategies. When idle, they automatically underclock to conserve energy. When busy, they automatically boost or overclock. The adjustments are so dynamic today ...
0 votes
0 answers
26 views

Calculating required capacitance for ESC?

I'm working on an ESC design, but I'm not sure what capacitance is needed on the output terminals to smoothen out the voltage sags. Any ideas on how to calculate this?
1 vote
1 answer
37 views

Is it possible to get an estimate of the power consumption of a circuit by modeling it with controlled sources?

Let's say I have an op-amp. We can measure the power consumption of the circuit by multiplying the current supplied by the voltage supply with the voltage of the voltage supply. Now, suppose this op-...
1 vote
1 answer
35 views

How should I select a battery solution for my project? (24 V/150 mAh with recharging)

I'm designing my first ever electrical project and have questions about selecting an appropriate battery solution. I'll put the requirements up front. Max power draw - 24 V @ 150 mA Average power ...
0 votes
1 answer
203 views

Design for portable PV charging for 97 Wh lithium-ion battery

The manufacturer of my medical device has provided a Lithium-ion battery with these characteristics: 97 Wh Output 3.75 A Input 100-240 V, 50-60 Hz, 1.0-1.5 A Protection: overcharge, overdischarge, ...
1 vote
4 answers
293 views

Trip RCD with a circuit

I am wondering if it is possible to trip an RCD safely with a custom circuit. I know the RCD detects current leaking to ground, so could a relay and a resistor be used to short the active to ground? I ...
0 votes
0 answers
39 views

Increase boost converter power

I am looking to build this DC-DC boost converter. I know what parts were used to build a 150 W version of this design. I would like to build a 500 W version which basically has the same input and ...
0 votes
0 answers
40 views

USB Charger (Samsung/Apple/Dedicated)

I have read a lot of lines about D+/D- Voltage when using different devices. Also the Article from maxim integrated. The conclusion is: I test it with iPhone X(iOS 15.6.1) and i found something ...
2 votes
4 answers
142 views

Why can't current flow in a conductor with a potential/emf on one end and earth on the other? Is there a mathematical expression?

Let's say I have a wire with one end connected to earth and the other end floating. Now let's induce a voltage/EMF of X volts into the wire. Considering the ground to be zero potential, why doesn't ...
-1 votes
0 answers
39 views

Wireless outlet for monitoring and control [closed]

My idea is to monitor power consumption and automatically turn off the outlet based on time and power consumption (e.g. at night, but only if nothing has been running for a while). Most important is ...
0 votes
1 answer
95 views

LED 12 V, 30 A power supply blinking and 0 V output

I bought a 12 V, 30 A LED power supply for a chemistry experiment (electrolysis). The power dropped to 0 and the onboard LED in the power supply started blinking when the anode and cathode were in ...
0 votes
0 answers
44 views

Converted PC power supply producing too much voltage

I have converted two ATX PC power supplies to 12V bench power. They have worked flawlessly for the past 5 years. Suddenly, both are providing 17V+. What could be causing this? I have a 10ohm ...
0 votes
1 answer
509 views

IEEE 4 machine system: Need help in computing the bus admittance matrix

I need help in computing the bus admittance matrix for the following Kundur's 4 machine 2 area system: ...
0 votes
2 answers
50 views

48 V phantom power backup: switch off the 9 V backup battery with FET

I found this device here on the site. I need something to switch to a 9 V backup battery when there is a 48 V phantom power outage. How can I change the FET to switch OFF the BAT1 (9 V) backup battery ...
0 votes
0 answers
56 views

Will these 2 electromagnet produce a 40kg (400N) attractive force?

Dear all, theoretically according to the electromagnet datasheet, it can attract with 20kg force, does that mean if I have 2 of the same electromagnet and if I switch it to different polarity from ...
3 votes
2 answers
91 views

RLC resonator to produce beautiful sine wave

simulate this circuit – Schematic created using CircuitLab I have read about the RLC tank which can help to resonate a pulse wave of a certain frequency so that it will produce a beautiful sine ...
4 votes
2 answers
1k views

Why is load rated in kW? [closed]

Why is a load always rated in kW and not in kVA or kVAr? Isn't it better to know how much kVA or kVAr an appliance or device has? Isn't it more useful?
3 votes
1 answer
299 views

Diode datasheet: What is "AI PCB" in the image?

What does "mounted on AI PCB" mean? Please explain with some pictorial examples.
0 votes
1 answer
48 views

Can you calculate equivalent capacitance across a MOSFET if you know the rise/fall-times and voltage across it? [closed]

In my high frequency supply my MOSFET VDS signals seem to be falling/rising at much slower rates than the data sheet would suggest for a Gallium Nitride switch: https://www.ti.com/lit/ds/symlink/...
0 votes
0 answers
32 views

Rotary inverter to transmit stable and high-quality power for power system with high penetration of renewable energy [closed]

From your point of view, do you think the highlighted information above is true? I think it's true and would like to do a research where I will replace electronic inverters with a motor generator set ...
0 votes
1 answer
440 views

PMIC battery charger and power path

I was looking for a PMIC with a battery charger and built-in power path when I came across one of TI's new chips, the BQ25601. While I was trying its performance and doing some tests I noticed that it ...
3 votes
2 answers
274 views

Demodulator circuit design

Below is Triangular Modulation Output of a Triangle input wave Below is weird Modulation Output of a Triangle input wave when it is connected to demodulator The modulator circuit is quoted from Andy ...
2 votes
1 answer
116 views

Drive a coil with an Arduino

I want to drive a coil with a PID controller on an Arduino. I already made it on my computer, so the PID itself is not a problem. The coil has a resistance of a little less than 1 Ω, an inductance of ...
-1 votes
0 answers
27 views

why isn't \$P=P_c\$ where \$P\$ is the power that we want to supply and \$P_c\$ is the power lost during transmission

When deriving the power lost during transmission, we use the following two formulae \$P=VI\$ where \$P\$ is the power that needs to be supplied, \$V\$ is the potential difference, and I is the ...
0 votes
1 answer
40 views

Reset push switch for LDO regulator

I have a XC6220B331MR-G 3.3 V LDO voltage regulator that supplies power to the MCU along with some other components on my board. The regulator has an enable pin which I connected to VIN so that the ...
2 votes
1 answer
256 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 ...
2 votes
2 answers
4k views

TEG in series require power balancer/align adapter?

Do Thermoelectric Generators (TEG) in series require a power balancer, when storing the energy to a battery source? If not, what should I do for my design to distribute to a battery source more ...
1 vote
0 answers
24 views

Low-frequency inverter power transformer selection

I'm currently designing a low-frequency inverter from 42 VDC to 220 VAC (effective) that goes up to 300 W. The block diagram looks something like this: This is the FFT before the filter: As you can ...
0 votes
0 answers
45 views

AC/AC power supply for PCB

I am trying to source the right setup for powering this PCB: I have found an 18 V AC/AC power supply but it has a barrel connector: I am struggling to work out how to connect the barrel connector to ...
0 votes
1 answer
72 views

INA219 load voltage stuck at 1 V

I’m using an INA219 and I’m trying to take a reading of voltage and current. When I’m looking at the current reading, it looks perfectly fine, however, the load voltage remains the same and it is ...
1 vote
2 answers
445 views

Battery life: 2xAA or 4xAAA - which is better?

Which will provide longer battery life: 2xAA batteries in series or 4xAAA batteries in series regulated to 3V via a voltage regulator or buck converter?
2 votes
2 answers
885 views

Cascading resistors in series

Suppose, let's assume an IC pin requires a 10kohm 1% tolerant resistor connected to ground for its proper operation. In that case, can someone tell me whether I can split the required resistors into ...
0 votes
1 answer
278 views

Can a switch take a higher voltage than it's rated for if the switching power is low?

I have a very basic toggle switch rated for 30 VDC and I need it for a 20 mA @ 36 VDC application. According to the datasheet, it's rated for 6 A @ 125 VAC, 3 A @ 250 VAC, and 4 A @ 30 VDC. In the AC ...
-1 votes
1 answer
69 views

Powering MCU and LCD screen

I’m using a 7805CT to regulate power for an Atmega328p for a project with an LCD screen. At first I was planning on having the LCD screen connected to the output of the regulator as well until I ...
2 votes
1 answer
2k views

Arduino controlled bench power supply

I'm looking for a schematic to control LM317 and LM337 from Arduino via digital Pots MCP42010. I'd like to build this schematic (input dual 30V, 500mA transformer per coil) However, with digital pots ...
0 votes
1 answer
20 views

LiPo battery choke and cutoff momentarily when connected to heavy load

I bought a couple of this lipo batteries it outputs a 4.2 V when fully charged nicely but trying to use it with coreless motors that draws about 3 A of current each, the battery just gives a surge of ...
3 votes
1 answer
127 views

Awesome magnetic levitation using Arduino

I followed a Youtube video here and it has instructions at here. The concept is easy which is try to levitate a magnet and balance it using Hall-sensor by changing the PWM of the electromagnet to ...

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