# 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: $P = I\cdot R = I^2 \cdot R = \frac{V^2}{R}$

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### Can you help me understand W=I*V - house load

So I'm trying to work out my daily Ah usage for an off-grid set up (and to see what my power bill at this new place might be like). Context: I've gone through and created a sheet with the appliances I ...
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### How does an AC of 5100W (1.5 ton) capacity work without any issue with 1000W of total electricity load of my house? [closed]

I have one AC of 5100W (1.5 ton) capacity and I generally run it along with other appliances like fans, LED bulbs, TV and more. My house is sanctioned ...
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### Power supply watt calculation [duplicate]

I have a laptop power supply with the following info: Input: 100-240V~1.5A 50-60Hz And my country's power line is 220V. So now what are the watt calculations and the used amps? What if this laptop is ...
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1 vote
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### What is the most electricity that can be transmitted over a typical power line of the US electricity grid?

I am trying to understand how much electricity can be sent over the long-distance high voltage interconnects in the US (not sure if this is what is more relevant to me -- the context of the question ...
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### Resistors lose resistance after a while

I have 3 different batch of resistors (10k 0805 SMD) which all fail the same way. I am supplying 5V across the resistor, with an ammeter connected in series. For the first hour or so everything go as ...
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### How to properly calculate the run time of a battery using a power converter?

I want to buy a 12v 100ah lithium battery to power a 750 watts power converter that provides 120V. I would like to know how many hours of energy will I have with this information. I tried some online ...
1k views

### Heater requirements to quickly heat a large aluminum sheet

I'm building a sublimation heat press. I have a 1000x250x8 mm sheet of cast aluminum. I will be using a thermostatically controlled silicon heat mat to regulate the heat up to a maximum 392 degrees ...
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### Help with a DIY tone board - selecting power supply wattage, grounding, and bypass switch

I plan to build a tone board with this module AIYIMA HiFi 2.0 Class A Preamplifier Tone Board Power Amplifier Preamp Treble Midrange Bass Volume Control With ALPS The power supply is "Supply ...
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### Limiting current/power dynamically

I recently installed solar panels and now I was looking at using the energy as efficient as possible. All the energy produced I don't use goes to the grid, I get a small amount of money for that. I ...
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### Is this PSU safe for this Christmas light string

I have an orphan 50 LED Static light string with label stating:- "Complete supply chain 3V, 1.5W, IP44" which has no power supply. I also have a power supply which is also orphaned i.e. it ...
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### DIY Bluetooth speaker

This is my first project. I have two 2 ohm, 12 W speakers. I need a very good quality sound amplifier with Bluetooth if possible. Is the PAM8610 good in terms of sound quality? Can someone suggest an ...
984 views

### How to calculate the effect of different voltages on an incandescent bulb?

How can you calculate the effects of running a 120 V, 7 W lamp on, say, 80 V, or any other voltage? What will the current draw be when you reduce the voltage? Is it possible to calculate knowing the ...
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### Learning about DC voltage [closed]

I have a step up booster that increases my 36 V battery to 50.1 V. If I plug it into my 48 V battery which charges to 54 V it still reads 54 V on the multimeter. I'm wondering why. Could it be ...
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### Question about RF waves and it's effect on electronic devices

Could a let's say 50 W RF wave (2.40 GHz and 5 GHz) cause disturbance in nearby devices like Laptops? (Data corruption, random opening of applications and programs, random commands, etc.)
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### Can a generator with rated ouput 2.5kW handle 2 PCs rated 600W and 500W connected to two UPS rated 3000VA/1500W and 2000VA/1200W [closed]

I'm having issues with different answers from ChatGPT and Bard. I'm not an expert so I would appreciate an expert opinion. I have a PC rated 600W connected to a UPS rated 2000VA/1200W with a power ...
1 vote
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### How to wire 2 different sets of panels to the same battery bank

My question is how do I add 2 different sets of panels to the same battery bank? I'm currently trying to design a solar array that will fit my tiny RV. Ive worked out how to fit 790w on my lil rig ...
94 views

### Coffee machine on solar powered current [closed]

I would like to have a Nespresso (capsule) coffee machine powered by a solar panel. This might sound a bit crazy, but I'm not sure it must be: This capsule coffee machine runs on a 12V car cigarette ...
122 views

### Wondering how to power this motor (universal motor?) with the correct power supply and using a pwm speed controller

This is a motor that I had lying around and so I did a bit of research and found that it’s most likely a universal motor. As shown, the motor says 120v and 60hz (which I assume is the AC and DC rating?...
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1 vote
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### Should I consider maximum power or typical power when I select LED power?

I have datasheet: https://pdf1.alldatasheet.com/datasheet-pdf/view/635258/OPTOSUPPLY/OSI3XNE3E1E.html There is maximum power which is 2 W and typical which is maybe 1.19. So the LED is 2 W or ...
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### Its possible to link a group of 1/4 W resistors as an alternative to a resistor with a high power rating (1.25 W)?

I have 10 resistors. Each one is 10 Ω. Is it possible to reach 3.3 Ω with a power rating of 1.25 or 1.5 W? I tried to get 3.3 Ω by linking in parallel (3 resistors), but the power rating is not high ...
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### How a 3-phase system delivers more power?

In a 3-phase system, when one phase hits the peak and is about to go down, the next phase starts hitting the peak, and there would be a total of six peaks as compared to two for a single phase system (...
1 vote
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### How I can get the watt from this datasheet? There is only current and voltage

I need the method that I can do to get the watt It says 250mW but how? I need that because I need to get the minimum voltage and also to get the current in some cases.
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### Can Watt’s law be derived from the Ohm’s law without using calculus?

Unlike Ohm’s law Watt’s law is not a fundamental law of electronics, as it can be derived from other fundamental laws of electronics. In the derivation above (see the pic) I used definition of current ...
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### Power supply amperage to wattage conversion [closed]

How many amperes would be needed for a PC power supply to run around 1000 watts RMS on a class-D mono block car amplifier in my house? Are PC power supplies the best option?
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### Why does the power factor of my fluorescent ballast seem to be impossible?

I have a ballast that's rated to run two 32 watt bulbs, which means (I think) that the working power is 64 watts. The line rating of the ballast is 0.5A at 120V, which means the apparent power (the ...
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### Calculate DC cable diameter

Please assist in defining the required DC cable diameter for the following requirements: Voltage: 48 volts Watt: 8500 watt Running distance: 50 meters
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### What is the ⎓ symbol (which looks similar to an equals sign) called?

What is the ⎓ symbol called, which looks similar to an equals sign with the bottom line broken into 3 dashes, and is used in consumer electronics?
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### Would a 20A, 12v fuse be functionally identical to a 1A, 240v fuse?

1Ax240V=240W 20Ax12V=240W Assuming both fuses are of the same type, would they be interchangeable? I'm aware that 240v fuses may not exist. I'm assessing the viability of substituting a 250v fuse with ...
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### How does an IGBT 120A, 450 watt welding machine inverter mechanism work?

How can "RYU Weld Machine Inverter 120A IGBT 450 watt" be advertised so? Does it really output less than 4V? How is such a rating determined?
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### Are watts and volt-amperes the same thing?

I understand that multiplying the voltage and amp-hours gives me the watt hours. I also understand that the volt-ampere is apparent power whereas watts are real power. What is the difference between ...
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### What part of wattage am I not understanding?

I was looking on the bottom of an electronic product and I noticed it stated these two things: Input: 5V 2A Audio output: 15 W I was taught V x A = Watts How is this device taking what I assume is 10 ...
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### How to heat a small enclosure using resistors; how many amps/ohms should the relay be?

I have a plastic case that I plan on heating with resistors. Temperatures could drop down to -40°F or possibly lower in an outdoor location. The only power that would be available is solar or two 12 V ...
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### What and how does a step up transformer work that converts a 120V outlet to a 240V outlet?

I've been fixing electronic equipment for some time and I've never dived into what a transformer really is. In my shop I have a 240V reflow machine that I run for at most 5-10 minutes at a time off of ...
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### Best way to measure watts usage from an 110V 2000W electric heater [closed]

I want to measure how much watts does my electric heater uses. It says it is a 2000W heater on a 110V outlet. I tried the kill-a-watt meter but that only goes max of 700W. What are some solutions to ...
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### 3 hp vacuum cleaner, but 1200 W rating [closed]

How can a vacuum cleaner say it's 3 hp, yet only be rated at 1200 W since 1 hp is ~750 W? The product description says it has a "3 horsepower motor" and that 3 hp is the peak.
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### Can I get more amps than SMPS is rated?

An SMPS is rated at 12 V and 30 A, 360 watts as output. If I step down the voltage to 5 V and use this 5 V with a device consuming 70 A, can this SMPS deliver 70 A of current with 5 V, 350 W, even if ...
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### How do I calculate a transformer's VA rating for a kitchen grinder based on its power consumption in Watts?

I imported a 110V kitchen grinder but a 220V one arrived instead. According to its included specs it consumes 150W and reaches 14500 RPM. In the case I start looking for a transformer for it, what ...
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### How to convert kWh to half hour time series?

I have an energy reading of 50 kWh. The duration of this reading is from 09:00 to 10:30 (or 1.5 hours). If I want to make a 30-minute time series, how could I convert 50 kWh into 3 half-hourly ...
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### How do you draw more current from a power supply?

Apologies if this has already been asked, but I can't find it anywhere. I was watching a video that described how one can calculate the power of something with this equation: voltage x current = power....
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### Use wirewound resistor as load

I want to use an array of ceramic wirewound resistor in series and parallel as the load of an 80W boost converter with the output of 400volts dc. Is it suitable to use 8 numbers of 10W resistors as ...
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### Calculating watt usage from an input/output electronics spec for step-down transformer's minimum watt limit

I'm trying to calculate the minimum watt limit needed for a step-down transformer that convert 220 V to 120V from source (220V) to 125V smart plug then to an electronic appliance with the following ...
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### PTC Heating Element Watt and Insulation Film | Hot Melt Glue Gun

Question 1 If two glue guns of 20 watts and 40 watts are receiving direct current from the electric board (no adapter). Then what makes one gun 20 watts and the second one 40 watts. Is it related to ...
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### Simple question on finding Watts and Wrms

I've done a bit of research but can't find the explanation for this problem, at least mathematically. I'm calculating W and Wrms of an audio amplifier by knowing output Vpeak and Load resistance. It's ...
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### Is the watt value on the device, or appliance label in watts per seconds or kWh? [closed]

I know the label says watts on the device, but since units of watts and kWh are used interchangeably to solve for amperage and calculating energy usage, it's not clear to me, and I can't find a ...
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### How long would a 48 volt battery with 40 Ah last with a 2000 watt motor?

If it is not over 3 hours what would be good to make it last longer? I am trying to build a 48 volt dirt bike with 2000 watts.
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### Can I replace a 12 V 40 W heating element with several 12 V 7 W elements?

Here is the environment: An RV fridge has a heat exchanger for cooling, looks like what you would stick on an IC chip, only 12" square. It has heater stuck on the back of it that is activated for ...
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### Calculating Fuse Panel Wattage

I am trying to figure out how many watts my house is drawing. I used a clamp-on meter to measure the current on the hot leg of my fuse panel which showed 128.8A. I am then assuming 120V which gives me ...
618 views

### Convert kWh during a 1 hour period to average 15 min kW output

If I have a photovoltaic system that outputs 100 kWh from 1PM - 2PM on a given day and I am trying to figure out what the average 15 minute kW would be during that time period, would that be equal to ...
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