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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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24 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 ...
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1answer
47 views

Faraday law (EMF)

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
43 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
47 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
62 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
20 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 ...
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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,...
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2answers
42 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 ...
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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 ...
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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
25 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 ...
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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 ...
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1answer
39 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 ...
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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 ...
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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 ...
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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
32 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
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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 ...
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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-...
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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
53 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 ...
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2answers
65 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 ...
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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 ...
2
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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
30 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 ...
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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
33 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 ...
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0answers
48 views

This is a basic question but I'm confused please help [duplicate]

I need to power my circuit. I have a power supply of 12v 8.5 amp my circuit needs 12v 1 amp. What do I need to do?
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1answer
42 views

Can the location of the inductor on the board affect the operation of the microcontroller?

I have a voltage regulator, based on LM2596, in its circuit there is an inductor on 33uH. The question is, can this inductor be a source of interference? Next to him, I plan to place the Atmega328P ...
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1answer
37 views

Typical Amplifier Output/Input Curve

I apologize for the extremely basic question, but I want to be sure. Ideally, an amplifier should have a linear output power to input power relationship. However, in most amplifiers (say a class AB ...