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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.

0
votes
2answers
101 views

Multiple Voltages Needed - Can I Simply Cascade Power Supplies?

Electronics novice here... I hope this is a reasonable thing to ask here. I haven't "tried" anything because I'm not really having a problem. I'm just looking for guidance before I start. I am ...
0
votes
1answer
19 views

How does Flash*Freeze reduce power consumption in Microsemi FPGAs?

Microsemi FPGAs are marketed as being low power. They have this flash freeze mode that is supposed to achieve much lower power dissipation, down to micro watts. I am trying to understand how exactly ...
1
vote
2answers
91 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 ...
-3
votes
0answers
91 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
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
51 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 ...
3
votes
1answer
156 views

Safety Capacitor Selection

When selecting an X2 safety capacitor what must be taken into consideration. There are only a few types of capacitance ranges and seem to be chosen based on voltage rather than capacitance. Take ...
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
2answers
121 views

Metal Halide Bulb with Instant On?

Is it possible to produce/obtain a metal halide (MH) bulb with the possibility to turn it off and on instantly - again and again? Most MH products require 30+ minutes to restrike.. Why is this? ...
0
votes
3answers
172 views

220 VAC/110 VAC to 24 VDC

I'm trying to understand how to build a battery charger. I need to convert from the usually european 220 VAC to 24 VDC but also from USA 110 VAC to 24 VDC like the normal chargers, to adapt it to the ...
1
vote
1answer
17 views

Matrix-Vector equation for active and reactive power in a transmission line

Suppose that we know vtilde (the complex voltage phasor vector at all buses), C the incidence matrix for a network, ...
2
votes
1answer
28 views

Distribution-side voltage regulation and Low voltage ride through (LVTR) curve

Nowadays, I see that photovoltaic systems have Low-voltage-ride-through capabilities. So in case of a fault, when the voltage is decreased, they remain connected to the grid and provide reactive power ...
0
votes
1answer
73 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 ...
0
votes
2answers
117 views

6 volt drop to 1.2 volts

I am working on a circuit for my deer feeder. I now have a 6 volt power source running the spinner on the feeder and it has a 6 volts solar panel recharging the battery. I made a new circuit control ...
1
vote
2answers
90 views

Finding the average power dissipated in a resistor

Well, I've a series RL circuit that is powered by a voltage source. The input voltage is given by: $$\text{V}_{\text{in}}\left(t\right)=50+\frac{400}{\pi}\cdot\sum_{\text{n}=1}^\infty\frac{\sin\left(...
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/...
5
votes
3answers
11k views

Voltage Drop and Safe Current Load on CAT5 Cable

I am going to use this passive PoE injector cable set to power a Raspberry Pi model B. The Raspberry Pi model B consumes between 700mA-1000mA (mine will also be powering the RPi Camera Module). Using ...
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
2answers
859 views

Logic Gate Power in Proteus

Can someone explain to me how you can power (vcc, vdd whatever) a logic gate in Proteus, with only the input and output pins being shown? Thanks in advance. The above is the circuit I want to ...
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 ...
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
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 ...
-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.
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?
2
votes
3answers
206 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 ...
4
votes
2answers
109 views

How to use the electricity from a generator in an efficient way

I'm looking to buy a generator for producing electricity to power different things (e.g. a fridge), in a place where there's no electricity. For now, I do not have a fridge but I may have one in the ...
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 ...
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 ...
1
vote
1answer
101 views

Latching power switch circuit

I am trying to understand: 1) how the following circuit works and more specifically how it turns on. 2) How to to modify it to get a hold on/hold off behavior instead of push on/hold off to prevent ...
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 ...
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 ...
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 ...
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
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 !
2
votes
1answer
89 views

Why symmetrical component analysis is necessary for fault calculation?

If a 3 phase fault occurs the direct axis sub-transient reactance is sufficient to calculate the fault current. But in case of an unbalanced fault it is not. Taking the example of Line to Ground ...
4
votes
2answers
232 views

Flyback Converter Capacitor Value selection with given ripple voltage limit

I need to design a flyback converter for my project. In my design the output voltage is 15 V. I calculated all the parameters including inductance values, diodes selection etc. However there is a ...
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 ...
2
votes
3answers
1k views

Any good method for the power down sequence?

In my circuit, +12V would be supplied by an external power source. After two regulators, two more voltage source(+5V and +3.3V) would be produced and supply power to adc AD7682.Because of the maximum ...
2
votes
3answers
779 views

Can I increase the no of operating hours of a battery without increasing its capacity?

Setup Let's say I have a 12V / 1Ah rechargeable battery pack. A device that consumes 0.1A will run for 10 hours. When the battery drops to 8V, the voltage will be insufficient and the device won't ...
-3
votes
2answers
99 views

How to power a large RTL project?

I saw this yesterday, and I have been thinking about this: How is all that powered without losing any voltage or power over parts of the project? Would the battery just end up having more energy ...
0
votes
1answer
97 views

Estimating the current consumption of a DC motor

Good day, I am wondering if it's possible to estimate the continuous current consumption of a DC motor vs startup or rated current. I am trying to put together a solar powered aquaponics system. 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
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
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 ...