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Questions tagged [power]

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

-3
votes
0answers
85 views

Is the US Power grid's voltage the theoretical maximum? [on hold]

At this point, most of the people on this site who live in America know that the voltage of common power circuits is around 120 volts. My question relates to the use of voltage dividers in a circuit. ...
1
vote
2answers
85 views

Firmware only runs when I press the reset button

I've created a board using the STM32F405R6T6. I am experiencing some problems: after I program the firmware onto the microcontroller, withdraw the power and reinsert, the firmware only starts to run ...
1
vote
0answers
27 views

What are suggestions for designing a circular electromagnetic accelerator? [on hold]

I am currently planning to build a circular electromagnetic accelerator, think a particle accelerator that is accelerating a macro-sized projectile instead of an elementary particle. My current ...
1
vote
2answers
49 views

What happens if LEDs do not get enough current? [duplicate]

I'm building a lighting fixture using big led panels. The LED panel says it requires 7 amps @ 12 volts, but the power supply I have is only rated to 4 amps @12 volts. What will happen? Will it ...
2
votes
1answer
62 views

How to setup the oscilloscope for measuring power supply response

I need to measure the overshoot and to modify some capacitor values in the feedback loop of the operational amplifiers in order to find the best response of the power supply (it's a linear power ...
7
votes
3answers
2k views

If a lithium cell is said to have a capacity of 20 Ah, does that mean all 20 Ah can be used?

Toshiba's SCiB 20 Ah Lithium titanate cell is said to have a nominal capacity of 20 Ah. The cutoff voltages are 1.5 V and 2.7 V. Does this mean that all 20 Ah of charge exist between those two cutoff ...
0
votes
1answer
69 views

Power supply destroyed when I connected positive line before ground

I have a few switching dc-to-dc power supplies (36V to 3.5V) which gets destroyed when I connect the positive input line before the ground. When I connect the positive line first, some very quick ...
1
vote
0answers
22 views

Battery Powered System and Input Capacitance

I have a battery powered system in which the battery is connected to a buck/boost converter to derive 3.3V from two or three AA batteries. The regulator I'm using is a TI TPS63050, and it has a power ...
-1
votes
2answers
67 views

power supply by using stepdown transformer

i was trying to make 5V, 1Apower supply using stepdown transformer, some doides and capacitors and finally 7805 regulator. however when i tried to drive servo motor from it i was not getting stable ...
1
vote
1answer
32 views

Finding Norton voltage and resistance and max power

My directions for this problem are to find the power delivered when RL=3 and then find the maximum power. simulate this circuit – Schematic created using CircuitLab I found Rth = R1//R2 = 1 ...
0
votes
1answer
49 views

Solar Panel Not Powering Toy DC Motor

I made a 15v solar panel from garden lights which supplies 50mA of current in direct sunlight. For some reason it doesn't power a simple dc motor which can run on a 1.5v battery. Why isn't it powering ...
0
votes
2answers
64 views

How can we visualize active reactive and apparent power as areas in time domain?

Regarding AC power feeding an impedance, is it possible to plot an example of V and I versus time for an inductive load R+jwL and especially the instantaneous power on the same plot where we can mark/...
0
votes
0answers
41 views

What would be the recommended way of making a USB meter/controller [closed]

I would like to make a “USB monitoring device” with one USB power input and two USB power outputs. The needed features are: voltage metering current metering sense an output being used individual ...
0
votes
0answers
44 views

Designing a regulated 12VDC and 5VDC power supply

New here and trying to build a very regulated 12VDC and 5 VDC power supply for RPi. Is this circuit okay or overkill?
0
votes
0answers
75 views

Neon sign transformer as power supply

Can I use a high voltage neon sign transformer to charge a HV capacitor?
-4
votes
0answers
44 views

HV Capacitor power [closed]

Hi does anyone know what kind of high voltage power DC supply do I need using UK 50Hz to charge a high voltage capacitor 50/25kV.
2
votes
3answers
205 views

How can I change step-down my variable input voltage?

Ok so here's the deal: I have a variable DC Voltage source from 0-10V. I need to step that down to a variable source of 0-3V. This 0-3V DC will be fed to an Analog to Digital converter in a ...
3
votes
0answers
46 views

Power use question for a trail camera

I am trying to calculate how long that a trail camera can be deployed before the batteries run out. The trail camera in question is a Reconyx HyperFire 2. Here is a useful review of the trail camera ...
1
vote
0answers
60 views

What are these programming terminals for a 2 kW power supply?

Does anyone recognize the programming terminals on the real panel of this power supply? I would like to get the 50 amps out. It is an ATE1 made by Redfern radio, it is an old army surplus. Going in ...
1
vote
2answers
43 views

Powering multiple WS2812B strips from different sources, are all grounds connected?

I'm looking to confirm if I need to connect the ground of 2 LED strips which have different power sources. Adafruit says The key is to have all of the ground pins among the strips connected in ...
0
votes
2answers
71 views

Does connecting LEDs in parallel use more current then connecting them in series in my circuit?

Sorry if this is a dumb question, I need a sanity check on this stuff. Is it possible to give LEDs varying current, without sacrificing efficiency? Basically I have 4 LEDs which could all use ...
0
votes
2answers
50 views

Powering a device, which power supply?

I've got a device with a 12V input requirement like this: But I've got no idea what the name of this input type is, and after searching for the correct supply (needs to be powered from a 240V mains ...
-1
votes
1answer
72 views

Kirchhoff's laws circuit, How to calculate unknown resistor?

First time here! I got a question on a test that I cant get my head around. How do I calculate value of R2 ? Is it possible ? Thanks in advance !
11
votes
5answers
3k views

UART pins to unpowered MCU?

I'm using a USB-UART IC with an MCU, which is powered from a battery. The USB-UART IC is powered from USB connector, not from the battery, so that I don't need to open up a console every time when ...
9
votes
6answers
3k views

Is it necessary to separate DC power cables and data cables?

I have had this discussion with my colleague earlier. A DC power supply is non-alternating, so the magnetic field a DC power wire generates is constant (is it?). Now, I know the rule is to separate ...
0
votes
3answers
83 views

What are these latching wire-to-board power entry connectors called?

What are these connectors called? They are very common for supplying power to PCBs; the latch keeps them in place. This particular instance has 3.5mm/.138in centers, but I see them a lot, usually ...
12
votes
3answers
2k views

Is it safe to abruptly remove Arduino power? [closed]

If I have an Arduino, can I abruptly turn the power on and off without corrupting it? If I am designing a product that has an on/off switch, do I need to incorporate a delay before turning off the ...
0
votes
1answer
40 views

Harvest energy from ultra low current and high voltage source?

I have a sensor which can produce voltage upto 10 V but can only produce 50 nA of current. I tried to harvest energy using TI's BQ25570 evaluation board but the current is too low to kickstart the ...
0
votes
0answers
17 views

Under what conditions does a VSC require a DC-link capacitor?

For basic, conventional converters, such as the three-phase two- and three-level converters, the use of a DC-link capacitor makes sense to me. Considering only reactive power applications, it makes ...
0
votes
1answer
34 views

Why a pure resistive AC circuit absorbs power at all times according to this equation

Here is the equation of average power in a pure resistive AC circuit: "Fundamentals of electric circuits - Alexander Sadiku" How this equation imply that the circuit absorbs power all times, I ...
0
votes
0answers
18 views

creating artifical neutral point in delta connection

I am trying to measure 3 phase 3wire and 3 phase 4 wire L_L voltage and L_N voltage.Circuit i am looking is common for both. In star connection i will get an neutral point for reference to read the ...
0
votes
0answers
44 views

Can anyone identify this diode? S69D

I’m attempting to repair a totally dead Panasonic SC-HC30DB and have found a faulty diode in the secondary part of the SMPS. However, I can’t identify this diode marked S69D as you can see from the ...
0
votes
2answers
54 views

Measuring Power across a dummy load - use voltage or current?

I have a high power 8Ω resistor dummy load (approximating a speaker) which is being driven from the output of an audio amplifier. I want to measure the power consumption and display the results on an ...
0
votes
1answer
52 views

Will cutting data line of USB port can supply the right amount of current it is attached to?

I want to use a USB cable and an AC to DC adapter as a supply to my electronics project. I plan to connect the USB cable to the USB port on the AC to DC adapter then I will cut the other end of the ...
0
votes
1answer
42 views

Reactive vs Real Power in DC-DC Converters

I don't understand which form of power, reactive or real, should be dominant in a maximally efficient DC-DC boost converter. As the circuit charges the inductor, the current and voltage will be out ...
2
votes
0answers
32 views

USB Type-C DRP Integrated Switch/Interface Chip

I would like to experiment with a power bank design with a single usb type-c port. The port should have dual role, source current for charging other devices as well as sink current for charging itself....
0
votes
1answer
56 views

Power source project

I’m currently a computer engineering student from lorma colleges and we’re currently doing our design project. Our project is called an advance helmet. A helmet that is capable on creating a ...
0
votes
0answers
57 views

Power supply wires melted. Is there a way to fix it

We were testing a peltier module and turning on and off the power supply when magic smoke formed and it stopped working. The smoke happened immediately after the supply was turned on again. We were ...
1
vote
2answers
110 views

How do devices that are rated for 120/240 volts work?

I am about to go over seas and when considering powered items I am bringing, some things state they can take both 120 and 240 volts. What do devices usually do to make sure their output is the same ...
-4
votes
1answer
63 views

Crude Li-Po Battery Charging. Is it safe?

So I have this drone and I want to play with it but there are no chargers for it nor are there cables for this kind of li-po here but I have minimal knowledge with electronics, just enough to make ...
1
vote
2answers
63 views

How is Line and Phase Voltage the same for a Delta connected system?

I am having a little bit of confusion for some reason understanding how the phase and line voltage can be the same for a delta connected system, i understand why the current is different for the phase ...
0
votes
0answers
12 views

Reactive Power at Slack Bus

When computing the power flow solution, we find the (1) voltage angles at (a) load nodes and (b) non-slack generator nodes, and (2) voltage magnitudes at the (a) load nodes. We can then compute the ...
-1
votes
0answers
29 views

Steady state stability of power system

Is it by reducing fault clearing time or decreasing generator inertia for second question
0
votes
1answer
62 views

Power Transformer question to power a motor load

So I bought a toroidal power transformer that can output 117Vac, 12.8A and has a power rating of 1.5kVA in order to power a motor that requires 115Vac, 13A. I wanted to see if this would be viable to ...
0
votes
1answer
32 views

Total Power Dissipation - Design Margin

It is good practice to ensure some design margin for the electronic circuit in terms of absolute maximum ratings. What is the proper way of selecting such a margin for Total Power Dissipation? Let's ...
1
vote
0answers
39 views

Rise time and fall time issue in the power MOSFET

In our automated design due to MOSFET obsolete we have changed new MOSFET which gives us rise and fall time issue at the frequency applied from 10Khz to 500Khz. when we use the power MOSFET as Load ...
0
votes
0answers
38 views

Build 100-240v Power Adapter

I am trying to power a 5v circuit from any voltage between 100-240v. I know it is possible to do this with a transformerless power supply, but only for a single voltage (e.g. 120v only), but how do I ...
0
votes
1answer
51 views

Supply one device with two power supplies

i would like to ask if my schematics is ok. I have one (or more) device (here symbolic as "R") which are supplied by a main power supply. I would like to support them also with an usv for the ...
0
votes
1answer
73 views

Why am I measuring the power different than the given rated power?

There is a solenoid-valve where I measure its resistance as 55 Ohm across its terminals. The photo of its label is shown below: Above it says 24V DC 8W. But I measure the solenoid's DC resistance as ...
-2
votes
0answers
52 views

So I bought a 3.2VA 15V transformer instead. This should do a better job for the voltage regulator? – [duplicate]

Voltage regulator not outputing desired voltage and extremely hot This means that there will be only something like 700mW of power so no heatsink is needed.