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

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1answer
36 views

Changing voltage multiple times

I am trying to power an atmega328p, and the esp8266 for one of my projects. I am trying to drive a relay to switch lights on and off. The problem is that the relay runs on 12v, the atmega runs on 5v ...
0
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1answer
27 views

Understanding benefit of higher watts on power bank

I have seen multiple lithium power banks offering 5000mAh. The Price can increase substantially for the same mAh but a higher output wattage. My understanding of a 5000mAh battery is that this power ...
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0answers
26 views

Using a tablet without battery (and making it believe it has one)

Tablets have gone mainstream a few years ago, and Li-Ion batteries have a lifetime of a few years only. This paves the way for a new need for us couch potatoes: to be able to use a tablet when the ...
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0answers
20 views

Reverse wiring an automatic switch (MCCB). Is it possible?

I have an automatic switch which is used for electricity protection of system. Above automatic switch you can see the line and below the switch you can see the load(This is normal wiring). In fact, ...
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votes
1answer
52 views

regulator ac to dc with

I am studying for my EE exam ,I understand the general working of the circuit but there is some details about it I have to know. this regulator supply 24 volt with puissance nominale 200watt. it ...
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3answers
175 views

Linear Power Supply Advice

I am new here to StackExchange and new to electronics in general. As my second electronics project (the first being a blinker circuit for a bandolier of LEDs) I am building a regulated linear power ...
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0answers
31 views

Wheel Generator & power Clarification

I'm working on a home project for a rover, more specific on a wheel setup which can be applied to anything that has wheels. for example shopping car or Stroller, wheel chair. the basic idea is to have ...
2
votes
1answer
76 views

Why doesn't the RMS current and voltage give me average power?

Apologies for the multiple bridge rectifier questions. I have a 230V/9V 10VA transformer, and I want to know how much DC current I can draw from this circuit. From this I assume that the ...
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0answers
64 views

How can a circuit output have voltage, but no power?

I am building a triac/diac circuit for a motor. Currently, I am testing it with only 16V AC to see if it works. I don't want to risk electrocution. I am encountering a problem where the output voltage ...
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3answers
60 views

Motor undervoltage

In the situation of a motor losing voltage, say it's rated for 240vac, but it's only receiving 190vac, what happens in terms of the power triangle? Does current increase, does it slow down and reduce ...
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2answers
67 views

A Question on Resistance

A 19 v dc supply is switched to an IC amplifier. A 12 V dc, 100mA pilot lamp,(nonLED)is wired in parallel with the switch to indicate an active circuit. What size resistor is needed to support the ...
1
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1answer
35 views

Does Armature current decrease as the load decreases?

I am being asked to find the speed of a 16.5kW shunt DC motor that is being supplied with terminal DC voltage of 300V when operating at 50% rated load with an armature current of 30A. I need to use ...
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4answers
396 views

Is it ok to feed the output of one LDO regulator to the input of another?

Sorry if this is a stupid question, but I am mainly working with 5V PIC circuits and now want to integrate a component (nRF24l01+) that needs a 3.3V supply. As I have a box full of ~7V wall-warts, I ...
0
votes
1answer
57 views

How to connect a four route MOSFET to multiple power sources? [closed]

I have this four channel MOSFET switch: I have connected one RGB LED-strip to this, and controlling it from an Arduino, and this works great. The problem is that I need to control four of these ...
0
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0answers
27 views

TPS65146 LCD TFT

I'm using TPS65146 (IC LCD supply TFT 24-VQFN) to provide required supply voltages to run 7 inch LCD panel so I used a 24-VQFN breakout board with IC ready assembled and I just added the discreet ...
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votes
1answer
76 views

how to power up [closed]

Is it possible to power 10 x 100w led's 34-36v all the same. With one ac dc power supply if so what size power supply would I need. And would I need to do a parallel or series circuit? maybe some ...
2
votes
2answers
214 views

Type of switch for AC power cord?

I have a power supply that has only screw terminals for its AC mains input. Currently I'm using a power cord from a computer that I cut the female end off of and attached fork terminals to (live, ...
1
vote
1answer
66 views

What is the relation between the power dissipation in resistor and the temperature rise

Which relation we use to calculate the temperature rise in resistor using the power dissipation. If we take P=R*I^2 from resistor, how much the resistor heats in this case ? I know that in ...
2
votes
1answer
79 views

Power factor correction in a simple phasor circuit

I've been having a bit of trouble with a relatively simple power factor correction problem involving a simple circuit in the frequency domain (\$f=50\,\text{Hz},\omega=2\pi f=100\pi\,\text{rad/s}\$). ...
1
vote
2answers
55 views

Help with complex power and power factor correction problem

I'm having a bit of trouble trying to understand what is being asked of me in a relatively basic circuit theory question involving complex power and power factor correction. Now, part (b) and (c) ...
7
votes
4answers
383 views

Does an unloaded amplifier use more power at a higher volume?

Suppose we have a powerful sound amplifier, which is set at 90% of it's power, and nothing is being driven into its inputs. Is it using more power at this high volume (and producing heat, etc.)? Is ...
0
votes
0answers
54 views

Light powered by rocking kinetic device

I want to know if i can power a lower power light by simply rocking it. The light only needs to be on while its moving so should only require a small amount of power. I have included a picture that ...
0
votes
2answers
137 views

How to obtain a neutral point in delta connection?

If I want to connect a load from phase to neutral in delta, How do I achieve it. So far the closes thing I could think off is convert the delta to star. I may be wrong, please guide me to get a ...
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2answers
56 views

How to transfer electrical power from stationary to rotational part.that can be used for POV display?

I have been researching how to transfer electrical power from stationary to rotational part. Some of them showed the means by using slip spring rings like in this website ...
0
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0answers
26 views

How to obtain a 50 hz 240 Vac from a 3 phase PMG unstable frequency supply?

I have read about using a rectifier, buck/boost then a inverter at the end to achieve my goal. But is there any easier way to do this? I may fix my generator rpm, but it may result in low frequency. I ...
0
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2answers
53 views

Ensuring common ground in a circuit with several voltage requirements

I'm working on a project that has components requiring various voltages. 3.3v --- to power a set of laser diodes (qty 24 @ 50mA = 1.2A) 5v --- to power a set of infrared transceiver sensors (qty 24 ...
0
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2answers
75 views

AC vs DC and ELF - extremely low frequency

given : How do static fields differ from time-varying fields ? A static field does not vary over time. A direct current (DC) is an electric current flowing in one direction only. In any ...
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3answers
179 views

Electrical Consumption of Machine

I need to know how much electricity a machine uses in kW please. On the machine information plate it states: 460 volts, 60 Hz, 161 amps, and it is a 3 phase. I took the readings for the volts and ...
0
votes
1answer
58 views

Charging phones with lots of current [duplicate]

My question is, what if I want to charge my iphone that uses 5volts via USB, however what if I had a powersupply that could deliver 5volts upto 10amps, if I used this to charge my phone would it ruin ...
0
votes
0answers
9 views

Replaced outlet, no power to that circuit [migrated]

I am not electrician. I am a DIYer and have some experience with replacing breakers, doing basic electrical work, but nothing really "advanced". An outlet was recently cracked, and my roommate went ...
2
votes
1answer
166 views

How much current can you pull safely off a standard AAA battery?

This might be a stupid question. But how much current can you safely draw from a AAA battery. I am currently powering my project from a worktop power supply and it draws at 5V 0.45A during normal ...
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votes
2answers
66 views

RGB control with MOSFets

I would like to control RGB leds , or other PWN channels , using a micro controlelr, and ...
0
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0answers
37 views

Control multiple high current channels in mass production

We have to controll 4-6 channels with high current (3-5A ) ,with a micro controller, with control voltage of about 3v . One ...
0
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0answers
43 views

Full Bridge isolated power supply duty cycle calculation

I'm trying to find out what duty cycle to use for a full bridge power transformer from 180V input down to 5V output. The circuit looks like this without a capacitor across the input: . I understand ...
0
votes
1answer
28 views

Comparison of 180nm and 65nm CMOS technology in consideration of delay, power and energy consumption

how would each of them typically compare with respect to delay, power and energy consumption? (Used in digital circuits)
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2answers
64 views

Confusion: Power Bank and Mobile Charging [closed]

MI Power Bank 10400 mAh rated power bank. It has 93% conversion rate. It uses the USB standard to charge phones, so I am assuming a 5V output voltage. So the total energy 'content' = \$10.4A \times 5V ...
0
votes
1answer
44 views

Spread spectrum 400 KHz

I got a 6-phase DC-DC converter. Fsw=400 kHz, synchronization by external clock(CPLD). I need a spread spectrum 400 kHz. What's the best way? All chips what I've seen before worked on MHz and above. ...
1
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1answer
47 views

Inverting buck-boost vs. positive buck-boost

Should I use an inverting buck-boost or a positive buck-boost topology? Input voltage range = 19-22VDC, Output voltage range = 10-56VDC, Application = LED driver The app not I have says the ...
0
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2answers
52 views

Characteristic impedance of a transmission line

characteristic impedance of a transmission line depends on frequency of transmission as can be seen by its expression. What will be the characteristic impedance of TL if my signal has two frequency ...
0
votes
1answer
47 views

Mosfet IRF7457PbF voltage drop too high

I'm using a mosfet for powering an Arduino mega 2560 on and off. The current drawn is less than 500mA with a 12V battery. I chose the IRF7457Pbs (RS 543-0888), with these features: VDSS - 20V RDS(on) ...
0
votes
1answer
41 views

How to calculate logic gates power in microwatts in Matlab?

I am designing a circuit in Matlab2014 Simulink using logic gates and I am giving Pulse and Constant at the input of the circuit but I cannot measure current and voltage at the output of the circuit. ...
1
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1answer
48 views

Wireless transmission power for multiple receivers

I have just started learning about wireless systems and for some reason I'm hung up on what I feel is a fundamental idea. Consider some transmitter-receiver pair with isotropic antennas. The receiver ...
3
votes
1answer
85 views

Choice of heating element (power resistor)

Basically I need heating element which can heat up small volume of air (lets say shoes box size) up to about 60 C degrees. I am going to use 25 V source supply with 2 A current. What I thought about ...
1
vote
2answers
77 views

Best way to power a 3.3V circuit from 3.3V-to-5.0V source

I'm working on an add-on board that needs 3.3V power (~500mA) and should take power from its host board. The host can operate at 3.3V or 5V and I'd like to avoid using jumpers that would require the ...
0
votes
2answers
84 views

Transformer core maximum power

so i am an EE undergrad, and i am wondering if and how exactly does a transformer core limit its power capacity. From my understanding, the rated power of a transformer is due to the current carrying ...
0
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0answers
19 views

Rigol command to find if channel is enabled and max voltage/current can be applied

Hi I'm using RIGOL 832A in lab I just want to know if there's any command which returns answer 1. If channel is enabled? 2. Max voltage that can be applied to channel 3. Max current that can be ...
1
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1answer
76 views

Capacitive touch on off power switch

Is is possible to use capacitive touch as a power switch for an embedded project? Can a microcontroller turn itself off and somehow still monitor an input pin? Or is there a dedicated IC that can ...
0
votes
1answer
57 views

Mechanical Power (Application) and Electrical Power (Stepper Motor) Discrepancy

For my application I need a torque of \$\tau=0.87 \, Nm \$ and a speed of \$ w=140 \, RPM \approx 14.65 \, rad/s \$. This gives me a mechanical power \$ P_m=12.75 \, W\$. $$ P_m=\tau w $$ I have ...
0
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1answer
60 views

High power power regulators - thyristor regulator?

I am currently working on a system design that intends to control heating in different zones. All zones in total is calculated to use approx 340kW (230V). This will be divided into 11-12 smaller ...
0
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0answers
47 views

Protect the USB supply

How can i protect the USB power line from external power line connections? what's happening when i connect 5V line from external power supply (such switching reg) together with 5V USB power line? I ...