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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.

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1answer
37 views

Could single-line power transmission be used for a space elevator's climber?

This question posted on the physics stack exchange has not received much attention. I thought the audience here might be more able to answer it. A space elevator is a sci-fi sounding mechanism that ...
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0answers
37 views

Boost converter output voltage error

I'm using LT3494a to generate 37v from 6v input. This is my circuit. According to the datasheet, this chip can provide up to 40v output, so it should be able to generate 37v. Also, the simulation ...
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1answer
35 views

Why is this voltage follower not working in Proteus?

I have a 4th order bandpass filter which needs to be biased using 1/2 Vcc. I am trying to achieve this using a voltage follower. The bandpass filter was constructed using Multiple feedback topology as ...
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0answers
26 views

Electric Power Transferred on a Load

I got this problem: A transmission system is composed by an amplifier and the antenna. The transmit amplifier has an available power of 2mW and a resistive impedance of 10Ω. The antenna (in series ...
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1answer
24 views

Multiple boost converter voltage pulled down

I need to make a simulation of multiple boost converter design for different load ratios. I have designed 2 boost converter both of them have same duty cycle and same L and C values. Voltage input is ...
0
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1answer
47 views

Faraday law (EMF) [on hold]

Is is true that the magnetic field generated by a conductor conducting around 20A will not be sufficient in order to provide an EMF of around 3.3V? The frequency of the AC signal is 50Hz. Based on ...
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0answers
12 views

Window discriminator adjusting the reference Voltage (TCA 965)

I´m trying to build a Window discriminator, I´m using a Siemens TCA965. Looking at the datasheet, I´m a bit confused on how I can adjust my reference voltage. Maybe it´s actually better to put an ...
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1answer
45 views

Push Pull Switch Mode Power Supplies

I am reading this material for understanding the switch mode push pull power supplies. Push Pull Switched Mode Power Supplies I am unable to understand the working though. Can someone provide a ...
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2answers
40 views

Wha't the difference to use the junction to case thermal resistance instead of the junction to lead thermal resitance?

In case I have a diode, and I want to know it could dissipate the power, I have two values, but I can't choose between them: - Junction to ambient thermal resitance \$R_{ja}\$ - Junction to lead ...
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0answers
70 views

NanoPi Neo4 Power supply scheme help

Title might seem a little misleading, but honestly quite hard to word a title for my particular problem. The board design I'm working with combines the NanoPi NEO4 minus specific components which I ...
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1answer
48 views

USB Power Only - Detect Device Plugged In

I have a project that I need to complete for work. We have been working on this project for a while, however I have come to a bit of a road block. I'll first lay out the important points. We have a ...
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3answers
1k views

Why do we use a transformer on some heating element projects when the wattage is the same on both sides of the trasformer?

On some projects involving heating elements there's a transformer being used. and the explanation given is "we are using a transformer because need more current" but since the watts on both sides of ...
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0answers
58 views

Much higher energy use, maybe due to an old electrical heater? [migrated]

We had an 100% increase of power consumption last and this year. It is mostly the night-tariff, which we now consume 27'000 kWh The day-tariff is only around 2'500 kWh. First we thought this may be ...
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0answers
65 views

Power switch - IN and OUT connected all the time

A while ago, I asked about detecting whether a power jack is connected or not, in order to select power source from USB or DC jack. You can see the question here: Power selection circuit for USB or ...
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0answers
44 views

Arduino power up [on hold]

I have build a home CNC, I use Arduino Uno and a CNC Shield. I have build all the electrical board, to power the PC, the Arduino, the spindle/laser, the switch have 3 states OFF, PC ON and Aux ON. ...
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0answers
43 views

Advice for Amateur needed [on hold]

Sorry if this question is inappropriate, but I'm just a noob who desperately needs some help, so if anyone could take his/her time to help, I would be sincerely grateful for whatever you could do. I ...
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1answer
41 views

Controllable power source (current) with one transistor and one resistor

I have this circuit: It should be a controllable powers source for current. Is that right? 1) What's the name of this circuit? 2) What does the resistor and how can I calculate it? Thank you!
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0answers
21 views

Calculating Load Power in a transformer circuit

I've been learning about AC circuits and they seem pretty straight forward, except when it comes to transformers. I have this circuit and I want to figure out the Voltage and Power at R2, and also the ...
0
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1answer
16 views

Balanced delta source to Wye source by considering magnitude only is ok?

I read and derived formulas for balanced delta source to Wye source; it is given by Vy = Vd / sqrt(3)<30 but in some places I see people only dividing by sqrt(3) for conversions are keeping angle 0,...
0
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2answers
43 views

Am I misunderstanding steady state power disspation calculations?

I am looking at the Littlefuse 5KP series. It says on the datasheet: I am trying to understand how they arrive at \$P_D\$ = 8.0W. Given thermal resistances of 40°C/W or 8.0°C/W, and 100°C ...
0
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1answer
35 views

Help needed for HV DC/DC converter

I need to design a boost converter that outputs ~20 mA DC and an unloaded voltage of around 68-100 V. The inverter will be part of a Zener diode analyzer. I built it on the idea of the Joule thief (...
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3answers
41 views

Power determination for resistive load

I am a mechanical engineering student and i need to measure electrical output. I have some voltage and current measuring instruments. I used them to measure the voltage & current of a blower(...
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0answers
18 views

Split Power Plane when using Load Switches?

To do power saving for a battery operated product, I am using couple of load switches to shut down peripheral power when not using that. PCB stackup - Signal(component), Gnd, Power, Signal -- 4 ...
0
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1answer
21 views

Peak-to-Average Power Ratio in OFDMA Communication

I am looking for a formula to calculate the Average Power of a square wave used in APSK Modulation. In my textbook, the example above is given with no formula so I am a loss how the value for ...
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0answers
26 views

Calculating reactive power given u(t) and i(t)

I would like to calculate the reactive power of a given two-pole which has the following voltage and current characteristic. \$u(t) = 2+5sin(\omega t)+2sin(2\omega t+\frac{\pi}{6});i(t) = 10+3cos(\...
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1answer
59 views

Altering schematic for adaptor

I am trying to make a PCB for the attached schematic (mixer.jpg). Rather than run on 2 9V batteries, I would like to plug it into the wall using a +9 / -9V DC power supply. Do I need both diodes and ...
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0answers
39 views

Odd Ground/Power(?) issue with Mixing Desk - alternate grounding?

I am a bit stumped with this one. Unfortunately there are a few variables involved, but I will do my best to ask an answerable question.... I just built a DIY synthesizer. It functions absolutely ...
0
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1answer
35 views

Turning on a PC with a Orange Pi

I have been working on a system which allows to turn on a PC without physical presence. I'm using an Orange Pi platform with a board designed for testing the embedded systems. My assumption: green ...
0
votes
1answer
40 views

Calculating SMD resistor temperature rise

I am interested in knowing the actual power dissipation of an SMD resistor at a 70C ambient temperature. I am looking at a 10kOhm 2512 1Watt resitor RMCF2512JT10K0. from the electrical specifications ...
0
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1answer
38 views

analog signal generator output in Volts vs dBm

I am connecting a mixer to a microwave source and need to be careful of how much power I am giving to the LO and RF of the mixer. If I just stay in the unit of dBm, it would be ok but I became ...
0
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0answers
40 views

Problem using mosfet in my vape mod design

I'm trying to build a tiny 2xAAA NiMH battery vape mod. I know NiMHs are relatively more safer than Lipo or Li-ion batteries, and in my setting (coil's about 1.5-2 ohms) I could just directly connect ...
0
votes
1answer
39 views

Controlling the power supply of a bluetooth module via GPIO and a transistor

I want to be able to turn a Bluetooth module on and off via a GPIO pin of a microcontroller. My first approach to realize this with a transistor is shown below. Is this approach correct? If not, how ...
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0answers
41 views

Negative voltage supply

I've been trying to make a active load that would use a very small resistor, around 10mOhm as a shunt resistor. I've figured out how to make it, it's a common circuit, however since I need to use ...
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0answers
15 views

Power staging design with DC plug and charger

I want to build a device that contains a Raspberry Pi and a STM32F103 based MCU. It should run either with an external 5V power supply or with a built in LiPo battery. To keep things simple, most of ...
0
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0answers
43 views

AC voltage at the output of SMPS

We have 230 VAC power supply in our lab.A chemical earthing is done for this power supply. I have connected a SMPS (LRS-35-12) to it. The Output of SMPS is connected to a load of maximum 2A. I have ...
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0answers
30 views

Regulating 4s 18650 battery to 12V or use 5s instead?

I'm working on a power distribution board which is going to distribute to several other devices/boards. Due to the high current requierment of the all the devices in total (about 29A - mix of 5V, 12V, ...
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0answers
33 views

What would be a good constant source of power for a motor? [on hold]

A couple of friends and i want to build an orrery. We are having trouble in figuring out what would be a good power source for our motor. We are planning to use one motor to run the central gear ...
0
votes
1answer
31 views

What are my options for supplying power to an M140 M-Type JAPAN 2+ W laser diode running off of a 5A constant current laser driver? [duplicate]

Background: I am building a laser that is running off of an M140 M-Type 2+ W 445 nm laser diode and an adjustable constant current driver. Here are the specifications for both the driver and the ...
2
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1answer
87 views

Need some help designing a mains frequency converter (220v/50hz input, 220v/60hz output) for <$200USD

My main limitations here are with the amount of power needed, and of course the price. What I'm trying to do is to run a clothing dryer from the USA in another country, without burning out the drum ...
0
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0answers
31 views

How to safely switch a big inductive load with a Triac using a capacitor snubber?

I am building a Spot Welder with a big powerful transformer. I have to switch a big inductive load of 70mH (input of a transformer) The switching will be done with an SSR (Opto Triac Zero crossing SSR-...
1
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0answers
37 views

Issue with powering MP3 module with Amplifier

I'm not a electronics engineer/student, so please escuse me if my query sounds a bit naieve. I have a Mp3+FM module (link) which I can power with a regular micro USB charger(or desktop USB). As the ...
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2answers
75 views

230vac / 5vdc power supply design

I am making my own basic bench power supply mainly for testing logic gate circuits, relays, flip flops etc, that I can move around to different locations. The circuit of the entire schematic will be ...
0
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1answer
54 views

Drive a 3w led with a 18650 li-on battery

I'm getting crazy trying to figure out if there is any easy way to power up a SINGLE 3w led 3w - Forward Voltage: DC 3.2-3.4V - Forward Current: 500-700mA with a ...
0
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2answers
66 views

MOSFET as Power Switch Issues

I am trying to use a N-channel MOSFET to toggle battery power going to a 5V voltage booster using the circuit shown in the attached image. Battery voltage is 3.7V and the gate voltage is 3.3V. High ...
0
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1answer
59 views

How to choose the right potentiometer for dimming a LED

I have a reading lamp from IKEA. It has a bright LED. Too bright for my taste. So I inspected it and it is composed of a DC power supply unit that outputs 7V and a maximum of 3W. The LED unit is ...
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4answers
155 views

Converting Christmas Village from DC to AC

So this was the year we bought a AC-powered O-gauge Lionel train and a battery-operated village to add to our Christmas tree decor. The problem, the village eats batteries like a kid eats cookies. ...
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2answers
28 views

No negative terminal in power supply

I'm working on a project that relies on the Roomba vaccum cleaner's reference document (shown below), there are two positive terminals and 2 ground terminals. I'd like to understand: Why there isn't ...
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0answers
31 views

SMPS Flyback transformer selection

I am trying to design a SMPS for a project (I have to make a custom one for integration purpose). This SMPS have universal input (85-265V AC at 50 or 60 Hz) and an output of ideally 53V (but it can ...
2
votes
2answers
65 views

Help understanding power ratings in optocoupler datasheet

I want to understand this the datasheet for the Everlight EL817 optocoupler but don't know what is the maximum power can the output hold. I see an optocoupler as a kind of switch that closes a ...
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0answers
34 views

how do create a circuit that allows two power souces when one or the other is off? [duplicate]

I am trying to build a circuit board where the main battery power system is off and the temporary is used. Also when the main battery power is on the temporary is off. I want to turn my device on when ...