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Questions tagged [watts]

The unit of measurement and SI unit for power, named after James Watt. It is equivalent to energy flow per second or Joules/Second. In electrical terms \$ W = IR = I^2 * R = V^2/R \$

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Lower wattage of IR bulbs permanently

I have two 90w/12v infrared IR bulbs which is put into a r7s sockets. From thes socket goes in total four wires which is connected to our power supply. We have set two of the wires in serial so they ...
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2answers
72 views

Why does curling a wire decrease its amperage/wattage? [duplicate]

I picked up an extension cord today, and I noticed that it had a different value for its wattage and its ampage, based on whether the cord is wound around its base or not. (I apologize that the ...
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1answer
52 views

how do LED controllers work

I’m trying to find out if a device only draws the watts it needs to run or if it takes all available For example I have led light that’s says max 0,75 watts and the led controller says output 144 ...
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0answers
33 views

Equal Voltage, Higher Wattage

I am attempting to make a solar powered fan for my room. I am going to be using a 9V DC motor to spin the fan axis, and I have my choice between different 9V solar panels. My question is this: If I ...
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2answers
63 views

Electrical Power Question

I am trying to compare watts exiting the battery vs watts being consumed by the bulb. I have set up a test circuit shown below. Should not A-B watts match C-D watts?? Sorry for such a basic ...
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1answer
58 views

Are watts consumed in wireless electricity? [closed]

If I put a transistor on a coil of wire connected to a 120v AC circuit, and made it so my toaster was now wirelessly powered, if I turned the toaster on would it consume watts that are able to be ...
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2answers
138 views

Why does my phone charger consume more electricity (watts) when delivering less amps (slower charging)? [closed]

As far as I could understand, the charging speed is measured in amps. Like, if I use Ampere, it will tell that it charges in 2.5 amps, or 1.5 amps. I hope I got this right. Amps is the only ...
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2answers
73 views

How can I measure an induction cooker’s power with an oscilloscope?

I have to measure the current and voltage of a coil with an oscilloscope. In this case, does P Watt = Irms*Vrms? The induction cooker writes that the maximum Watts is 1.2K, but I measure it over 1.2 ...
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1answer
22 views

Is it okay to run a Mercury Vapor Lamp of lower wattage (100/150/175W) on a 400W MHL/MVL ballast? Also can a 60Hz ballast be used in 50Hz?

So, I have this RAB BMHH400PSQ Metal Halide Pulse Start Ballast 400W ,M135/M155 MULTI TAP 120-277V with me. Since the MVL are being phased out it has become quite difficult to get a ballast for one of ...
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2answers
126 views

Alternatives to High Wattage Resistors? (Do multiple low-wattage resistors equal a single higher wattage resistor?)

I am a beginner, so I may have made a horrible mistake in my diagram, but I am trying to learn. According as I have figured it, I am having an issue wherein I need a resistor rated for a minimum of ...
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1answer
52 views

How can I interpret the readings of a USB voltage tester considering the input voltage is 5V and I am charging a 3.7V battery?

I have this USB voltage tester that I place between my usb wall charger and a USB charging cable. This device gives me the total current that went through over a period of time. Let's say after 2.5h ...
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1answer
1k views

Motor current consumption and power do not match

I am working on a design and need to calculate the energy consumption of this motor: https://www.maxonmotor.com/medias/sys_master/root/8825428410398/17-EN-256.pdf. (Part No. 339252) The ...
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1answer
92 views

How to properly read Watt of a bulb power?

I'm confused about reading the terms Watt, Wh, and Ws of bulbs. Here is the quoted text taken from an electrical book that I'm currently reading on : Now I'm take out some points from the remarks ...
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0answers
36 views

4-pin ATX to 8-pin PCIe?

I'm building an eGPU, and I need to power my card with a single 8-pin PCIe connector. To keep the size small, I'm interested in using a 300W Seasonic Flex SUG PSU, which is just about the smallest ...
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1answer
59 views

A question about my refrigerator [closed]

it's written on my refrigerator 500watts.. I want to know how much it consume watts per month. let's consider that the compressor of the refrigerator works 10 hrs per day.
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1answer
267 views

12 Volt vs a 24 Volt Motor

I have read that using a higher voltage motor would need less current to get the same power. I understand that P = IV and how that works. My question is if the 24 V motor would get half of the current,...
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1answer
36 views

why does a potencial coil in wattmetter influences the pointer rotation

can somebody tell me, why does a potential coil in wattmetter influences the pointer rotation. if the ideal potential coil doesn't have current, it would not generate a magnetic field and it would not ...
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2answers
225 views

12 v watt heater with nichrome coil [closed]

i am new here. First of all I am sorry for my bad english. I want a help from those who know about nichrome heater coil. I want to make a 12v dc incubator using nichrome wire as heating element, all ...
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1answer
18 views

What wattage should I use for a switching adapter?

I have a bad switching adapter. It has a DC output of 14.5V 2.48A Max. I can't find a match anywhere. I think a 3.0 Max will work, but I don't know the wattage. The replacements I've found are 29W, ...
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1answer
71 views

Step up voltage Transformer for more watt?

Using generator in mountain or underground tunnel location, construction workers from portable generator gets maximum: AC Output: 220volt as 200 to 250watt Now, they need to use a machine for ...
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1answer
80 views

Does a 5w LED lamp require 5w/per hour to run ?

Does a 5w LED lamp require 5w/per hour to run ? eg. would 200 x 5w LED lamps running for 1 hour would require 1kwhr of electricity. Or is the 5w related to some other time scale ?
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1answer
612 views

How many watts does tweeter needs

I have a speaker with the following specs: Max. power - 600W Impedance - 4~8 Ohm Freq. response - 45Hz-20KHz Sensitivity - 98dB/W/M The tweeter of the right speaker is not working so i want to ...
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0answers
122 views

How can I measure the power given to a USB WiFi adapter's antenna in dBm or mW?

I have an Alfa AWUS036ACH USB WiFi adapter, and would like to know how much power is being given to the antennas (in dBm or mW). The Amazon link to it is here: https://www.amazon.com/Long-Range-Dual-...
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1answer
89 views

Not sure if this capacitor will blow up [closed]

so i have just bought a fan controller(silverstone cpf04) and it is rated with 2200μF and i am planning to connect 7 fans to it. (NF-F12)4 fans are each rated with 12v operating voltage 3.6w input ...
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1answer
51 views

Figuring out wattage

I know I can take volts * amps to figure out watts, but what if the device accepts a range of volts? So if I have a device that takes 100-240 volts, and is 2 amps, what is the wattage being used? Does ...
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6answers
472 views

How many D batteries would be required to power an 150watt/120volt Light for 8 Hours?

Here are the links to further data. Bulb info. D battery datasheet.
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3answers
685 views

How convert kWh to W

I want to know if there is an approximate or exact way to know the consumption in watts of household appliances in a house from the monthly consumption that reaches the bill. Taking into account that ...
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2answers
45 views

How to calculate battery ratings for your solar panel?

If I want to choose a battery for my solar panel which is required to run a load of 5 kWh/day. Then I will be needing a battery with a rating of above 23 ampere hours since 5 kWh/220 V (since 220 V we ...
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1answer
144 views

10 W LED COB on 12 V

So say I have a 10 W LED, most have a forward voltage of 9-11 V and a maximum current of 700 mA. If I wanted to connect it up to 13 V (a fully charged SLA battery) couldn't I simply do 11-13=2 (LED ...
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1answer
80 views

Converting 110v at 8.5 amps to 208 three phase amperage [closed]

I have some equipment that uses 8.5 amps and 1050 watts on a 110v. Any idea what the amperage would be on 208 three phase?
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1answer
56 views

Wattage of DC device is not equal to AC [closed]

I have a led driver (LPC-20-700) that is 30V and 700mA, which makes it 21W. I run 10 leds (≈ 2.8V drop) in series with it and it is an constant current device. If I plug my multimeter between, I do ...
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1answer
94 views

How is output power related to input power? [closed]

Please Note: I stumbled upon this forum after considerable googling but was not able to understand the answers I found. Your simplest terms and explanations are appreciated. I plan to bring a piece ...
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1answer
349 views

Power supply for Audio amplifier : high-voltage based watts or high-current based watts? [closed]

So I have these Philips (FW-V355) speakers, and I want to connect them to my PC via AUX or Bluetooth, ofc I separated them from their original old system/amplifier. In order to realise that, I bought ...
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1answer
194 views

Help with calculating voltage using watts/ohms (batteries/coils)

Okay, so I have no experience in EE (I do SE), so I don't know where to start. I apologize in advance this isn't the right place for this kind of question. I bought a vaporizer with a small battery a ...
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0answers
34 views

Replace a power adapter 12V/1A DC with 15V/0.8A [duplicate]

I have a battery-charger that has an input of 12V/1A as specified in the specs. Can I replace the adapter with a 15V/0.8A ...
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2answers
153 views

How do you measure/detect Watt-Seconds? [closed]

As part of a project I am working on, I am required to measure watt-seconds. I've looked this unit up online and it typically references to a camera flash. My question is how does one measure/detect ...
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2answers
68 views

Power calculation in kwh over a period of time with a variable current source

I have an experiment running which generates variable current due to a chemical reaction over a period of 8 hours. I sampled the current at each hour with a constant voltage supply of 12V. When i use ...
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7answers
1k views

Calculate the electric bill of a phone charger (AC adapter input or output?)

I need to calculate the amount of money I pay for charging my phone with this charger I know that I need to calculate the watts then kWh, so I multiplied 5 V by 1.55 A to get 7.75 watts and then use ...
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1answer
43 views

Plotting the instantaneous power of an RLC circuit

So I've been solving some basic instantaneous power/ average power problems and I've been asked to "draw" $$p(t)$$ which is the instantaneous power function of the circuit, I guess there are two ways ...
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3answers
103 views

Power plant cost accounting

For a 300 MW power plant, 14.5 MJ / kWh of heating capacity must be provided. For this you can use coal with a heating value (hW) of 29 MJ / kg and a price (P) of 35 € / t or gas with a calorific ...
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1answer
145 views

How can this MOSFET become overheated? How big should the heatsink be?

I've got a very simple circuit. A MOSFET (TK15D60U) is powering a 3 to 4 Ohm heat bed by 19.6 volts. From my calculations this results in 6.5Amps. The power adapter seams to have its specs at max 6....
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1answer
154 views

Will a man get electrocuted if he places the electrical test screwdriver on his foot?

Below is the typical circuit when somebody do the "test light" on wall electricity socket (Image 1): In this "images 1", very little current will flow into his body, because the high electrical ...
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2answers
56 views

Can I use low voltage but higher maximum amperage?

I have an electronic device (electromagnet solenoid) that working on 9V/DC and 30mA current (9*30=270mW) Question 1: If there is a 5V/DC adapter that could produce maximum 54mA (5*54=270mW), could I ...
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1answer
37 views

If watts exceeds rating? [duplicate]

I have been reading quite a lot on the subject in the past hour and I don't seem to be getting an answer, just about amps. I have a 2 watt rated ball valve, and I have a 12v dc 1 amp power supply. W = ...
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2answers
100 views

confused about power rating for washing machine in datasheet

I am interested in purchasing a Primus washing machine but I get confused about the power rating that is recorded in the data sheet (link below). On page 2 of the data sheet, the manufacturer states ...
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1answer
38 views

Understanding a motor's specs

I'm trying to understand the specifications of a brushless motor which I would like to buy for making an E-bike. Here are all the specs if have about the motor I'm interested in (copy-pasted from the ...
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2answers
99 views

Mathematically I have enough power but the power source don't seem like enough

Lets say i want to reach a certain wattage of 2,500 W. But I run it off a power source which maxes out at 5 A and 20 V. But I step the voltage up to 500 using a coil or transformer and now 5A × 500V ...
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0answers
46 views

Gate Drive Loss

Is there any difference between Gate Drive Loss and Gate Loss? (for example on a Power MOSFET) If there is a difference, then what would be the formula of each? Does switching On and OFF has an effect ...
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3answers
1k views

How do i measure watts on single phase power?

With a clamp on amp meter, I have 8.2 amps at 123.6 volts on one leg and 7.2 amps at 123.9 volts on the 2nd leg. When I touch the volt meter to both legs I get 247.8 volts. What is the total wattage? ...
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4answers
76 views

Stumped on an inverter [closed]

I'm disabled and am looking to be able to charge my power chair whilst I'm on the go in my vehicle, the problem is that I know what my charger draws and outputs in Volts and Amps, but all inverters' ...