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Search for wattage in Topics


I was out buying the parts for the free electricity from telephone port in wall, but the resistors have no wattage posted. The man at the electronics store said he needs the wattage for the correct resistors.

Topic by 3l3ctr1cman    |  last reply

Wattage of speaker? Answered

Hello, I have a variety of speaker that I would like to use in a project that I am currently working on, but I have found that there is oftentimes no information about my speakers on the internet, mainly due to the fact that I stole them from broken electronics. This makes things hard because I need to know the wattage of the speakers, but would prefer not breaking them to find out, especially since most of the time I only have one of those speakers. Basically, how can I figure out the maximum amount of power that can go into an unmarked speaker.

Question by Cheesey125    |  last reply

Tweeter Wattage?

Question by Delta1Dan    |  last reply

output wattage calculation?

Hey guys i have a 1100uf capacitor bank at 425V and the charge time is 30 sec does anyone know how to calculate the output wattage if the input voltage from the dc-dc converter is 12V at 3A ? thanks for all you answers :D

Question by coilsinamotor    |  last reply

Calculating amperage and wattage?

So I'm doing an energy inventory on our house to see how much electricity we use, and maybe see if we could cut down on some costs.  Being Christmas right now, we have a long multi-string chain of lights going across our living room. I'd say it's about 50 feet long. They are just regular incandescent lights. typical normal size, no LEDs or flashers or anything. When you plug them in, they come on, and that's all they do. I wanted to figure out their wattage, so I started with finding the amperage. My multimeter isn't very good when it comes to measuring amps, so I decided to use a roundabout method by finding the resistance of the circuit. The resistance came out to be 13.3 ohms. Plug that into ohm's law and you get around 9 amps of current and therefor, about 1080 watts of electricity. That sounded right to me...after all, it is a long string of lights, and even though they don't individually suck up a lot, I figured it adds up.  I tried this same method with a single bulb that I knew to be around 300 watts. The resistance came out to be about 4.5 ohms giving a whopping 26.7 amps with a wattage of around 3200 watts! That can't be right. I want to know what I'm doing wrong. I'm pretty sure it can't be my multimeter because I just bought it brand new about a month ago. What am I doing wrong?

Question by tylervitale    |  last reply

Mismatching speaker wattage?

Hey guys, So I've recently gotten into making DIY speaker systems, but I'm having trouble understanding the whole ordeal about wattage and ohms. I have four speakers I managed to salvage from some old speaker systems that I got from an old thrift shop. I have two 15W 4ohm speakers, a 20W 8ohm speaker and a 2W 8ohm speaker (but I don't think I'll find a use for that one, I'm not sure) I plan on buying the Lepai LP-2020A+ amplifier, it's a two channel amp and delivers 20W/ch with impedance of 4-8ohms. What I want to know is what set up would be best with what I have? Can I run the two 4 ohm speakers on 1 channel even though they would draw 30W of power? I'm a bit new at this, and my understanding is still a bit unclear so if anyone could please explain, I would very much appreciate it :) Thank you

Question by VoicesOnAir    |  last reply

Which is the best wattage for an resistor? Answered

I went to the electronics shop looking for a resistor, but they said for me choose the wattage! As far as I know, the wattage of a resitor is calculated by its current or voltage. Please help me!

Question by ace_gatling    |  last reply

Atx supply possible Wattages

Hi there community, i have a very certain question.I recently modified an atx supply of 420W. Some of its features are :5V 32 A 12V 14A3.3V 22A-12V 0,5ALets say i connect one end to 5v and the other to -12v, what wattage will this give me ? Probbaly not 17x32=544 Is bridging possible? What are the possible wattages ?Thank you for your time :)

Question by phevtron    |  last reply

I am trying to figure the new wattage? Answered

Hello, I built the ark welder from this instructable found at I'm trying to figure the new wattage I have two transformers 1: 650 watt MOT-primary at 120 volts 60 Hz 5.41 amps secondary at 16.5 volts 39.36amps 2: 600 watt MOT primary @ 120v  60Hz  5 amps secondary @ 16.5 volts 36 amps the primaries are wired in parallel in the secondaries are in series. The secondaries test at 33 V and I'm guessing roughly 76 amps. I want to calculate the wattage. Is the wattage calculator from the voltage on the primaries (120+120)*76 or calculated from the voltage on the secondaries (16.5+16.5)*76 or am I a complete moron? Also the primaries are parallel are they both 120 V or are they 60 V each thanks in advance.

Question by deadlift1979    |  last reply

Is there any way to find more info about a tranzistor?

I need to replace one on a circuit board, which controlls interior car lighting fade-in/out (12V).The lettering in it is extremely small but I can make out NP100. When I look at catalogs, I should also know the wattage, but I have no way to find out. Thanks!?

Question by Fyod    |  last reply

How do I measure Wattage? Answered

Alright, in my cold fusion set up I need to measure the watts going in and the watts going out.  How can I do that?

Question by Kalrag    |  last reply

two way radio wattage increase

Is it possible to increase the transmitting power on these modern cheap little two way radios like cobra and motorola and midland. they say up 35 mile range but only if both people are standing on mountain peaks

Question by gonzothegreat73    |  last reply

what would happen if resistors of lower wattage are connected to a power supply of higher wattage?

The power supply i'm using for a circuit has a higher power rating than a bunch of resistors i bought. What would happen if they are all wired together in one circuit?

Question by hmddeen    |  last reply

Can the wattage of a resistor be greater than used in an Instructable? Answered

I am working on a project that calls for 1/4 watt resistors. I only have 1/2 watt at the moment... Is it OK to use these for this project? Thanks!

Question by ElectroFlex    |  last reply

Q: input/output-wattage of poe adapter

Hi, i found an ubiquiti poe adapter 100-240v .3a input. here the q: the output is 24v .5 amps >> shouldnt the input/output-wattage be about the same (not considering losses due to conversion, heat etc)? i am confused (but then: i´m usually always, haha)bow.

Question by la xerra    |  last reply

Finding the wattage rating of resistors and variable resistors? Answered

Is there a way to find the wattage rating of resistors and such mathematically? or is it something that has to be tested in real life? I have quite a few resistors that I'd like to use, but don't know the wattage rating of them. I only know their resistance, and I could calculate other values if I put voltage across them with a multimeter.  Also, what type of variable resistor would you recommend to control a 12 VDC device that draws 12 amps?

Question by tylervitale    |  last reply

Set of dome tweeters (Too high wattage)

I have a set of dome tweeters that ran grwat on an old amp i had, thing blew out a few years ago, and just barely runs through another amp with the crossover and woofer. there is some jumpers in the crossover that say Tweeter attenuation -4dB stock setting --- -2dB 0dB Just as i put it right there. I want to know what attenuation means and how i can use the same amount of power into the tweeter, but make it louder. (It's pretty quiet.) Right now it is set at -2dB. Except the dB and numbers are lined up.

Topic by Yerboogieman  

can i increase wattage by the following way?

I think i can increase wattage by placing three coils in the following way / / / L m n among them 'L' as primary and m,n as secondary so that when electricity is passed through L magnetic lines of force from that coil induces current to 'm'.as electricity passes through 'm' it again sends magnetic lines of force inducing current in 'n'.so that connecting 'm' , 'n' in parallel or series will give me increased wattage

Question by lohithg    |  last reply

Lowest wattage Possible Computer for "World Of Warcraft"? Answered

Hello, I am looking for a low power (watts) pc to play world of Warcraft  I'm talking of a custom build computer Reason: I'm into solar power and green energy I have 2 Solar panels 1 15 watt panel and 1 30 watt panel. I like to play around and tweak computers ---- Aim: to get the lowest possible wattage computer to play world of Warcraft =========================================================== What I need you to do: Advise me on what components I need to buy example SSD hard drive ----------------------------------------------------------------------------------------------------------------------------------- Budget:  I'm afraid I'm on a budget at the moment as i only get paid £120 a month with £0 in the bank i can save up for a few months if required however. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Size: Size is not a problem _____________________________________________________________________________________________________________ Weight: Weight is not a problem ----------------------------------------

Question by Daniel Deacon    |  last reply

Does Increased resistor wattage effect peak amperage output?

Hello, I am in the process of building a 900W+ (60v  ~14a)  RC EDM generator. I am using a heavily modified hairdryer heating coil at  4 Ohms resistance at about 1200 watts. According to my calculations (derate transformer output wattage 20% in order to obtain minimum wattage required), I needed a minimum of 720 watts of dissipation on the resistor. Would it be okay to use a higher wattage resistor without any amperage drop on the circuit while it is operating?

Question by abadon    |  last reply

Need to regulate wattage based on resistance of an exchangeable part.

Ok, have a request. I need to make a compact device that will be DC powered (batteries) and produces a set wattage between 4.2watts and 12.7 ish. Can be a little lower a little higher on the scale. I'll be putting different attachments ont he end of this device that will have different resistance between 3-4ohm down to around 1.0ohm. I need the device to read the resistance and adjust the voltage coming from the DC battery to match the wattage I set. Basically if I set it to 10watts I want it to always be 10watts no matter what resistance attachement is on it. I hope that makes sense. I'm sure there's a pre-existing board made by some one out there that does this or that could be salvaged from another device but I can't find one. I know how to do variable voltage with a regulator but I need an auto sensing system where you set the output wattage. That goes a little beyond my expertise. Any help would be greatly appreciated, thanks in advance.

Topic by wallenc    |  last reply

How can I combine my 400watt and 750watt AC/DC inverters to get 1000+ wattage out of them?

I have both inverters and they both still work.  Instead of going to buy an expensive 1000 plus watt inverter I'm looking for a simple way to just combine the two I have to handle the wattage I need them for.  I go camping a lot and I like having hot coffee in the mornings, so I need an inverter to handle a coffee pot.  I could stoke the fire and put a perculator over it or crank up the generator and plug in the pot but I'm a simple guy who likes simply plugging in the coffee pot to my truck! 

Question by WildBill76    |  last reply

Inverter question? Answered

I have recently made a pond in my garden and to avoid spending lots of money in electricity, I decided that I would power it with a solar panel. My pump is 220v 34w, so I thought that a 40 or 50w solar panel should work. However, i can't find any 40-50w inverter, only about 150w. So, my question is, will a 150w inverter draw 150w from the solar panel if powering only the 34w pump? In other words, will a 40-50w solar panel be able to power a 34w pump via a 150w inverter or would I need a 150W solar panel for that?

Question by tgferreira184    |  last reply

What do 1/4, 1/2, 1 or 5 watts values mean on a resistor? Answered

I know that this is such a basic question but what do those values mean when selecting a resistor? 

Question by blkhawk    |  last reply

Help wiring an LED array

I'd like to buy some LEDs off ebay and build some LED arrays but I'm confused as to how to wire it. For example, lets say I have 100 watts of LEDs (aka 1 watt x 100 LEDs or 10 watts x 10 LEDs) as an extreme example and each LED has a max voltage of 12 volts. Then lets say I have a power supply that provides 100 watts at 12 volts. How would I wire it? I'm worried that if I hook it up, lots of LEDs will just burn out. Just help me understand what I need to watch out for here. I'm obviously a super novice. Have pity.

Topic by WillE2    |  last reply

how to increase wattage/amp output of a power supply? Answered

Hey everybody im back with yet another question. I have here a adapter for a motorola cyber surfr wave, i intend to use it as a sort of pico psu, since it outputs 5v and 12v. the only problem is that I dont think it supplies enough current or amps to meet at least a 145w psu's equivalent. I would also like to know what resistor or voltage regulator to use to get 3.3v. the 145w supplies: +12v 4.2a +5 18a +3.3v 13a -5v 0.3 -12v 0.8a +5vsb 2a the unknown motorola supplies: +5v 1.5a +12v 0.75a does it need -12v, -5v and 5vsb for the computer to work? does a picopsu supply those? I just need to switch the main transformer with one from a decent psu right? then the wattage will be increased? If i cant, how can i make a picopsu? i cant order online and have a extremely limited budget. there is a picture of the insides as well

Question by zack247    |  last reply

How do you work out the wattage of an amp?

I made the Ruby amp by runoffgroove ( and it's hooked up to a pc speaker with an 8ohm impedance, how would I go about finding the output wattage? And while you're at it if you have any amp-building knowledge to impart or good places to learn about amp circuits I'd appreciate it.

Question by OptimumAlliance    |  last reply

what wattage of laser necessary to kill mosquitoes (immediately)?

To craft a gadget that shoots mosquitoes with laser, there is the need to know the enemy's vulnerability. The most needed is the mosquito vulnerability to laser shooting. What wattage of laser is sufficient? The configuration I think is, attracting mosquitoes with some infrared light (or, multivibrator), then shooting with laser. I might shoot with a continuous laser (after infrared path is broken, surely), but zip-zip-zip sort of (threshold activated shooting) is sensible, too.I stated this previously @ yahoo answers, but no (serious) answer wa there.See the question there, a full, energy-harvesting mosquito-shooting gadget, a previous question might be related, too. That next question is about the malaria map (for energy harvesting, where necessary).

Question by ferzenr    |  last reply

LED Driver for LED fairy light strands

I bought several of these strands of leds I want to wire two of them together to make a chandelier with one dimmable power supply.  Each set comes with a 12 volt dc 1 amp power adapter. So, do I need a 12 volt dc 2 AMP 24 watt power supply that is dimmable.  I will be going from standard US electric 120 vac. I will be wiring then in parallel so that I don't have to mess with making the strand twice as long and worrying about more resistance. Mainly all the power supplies I can find are a little higher amps and more wattage. Could that blow them all? Any help would be awesome

Topic by Creativeguy  

Combine two usb solar panels for higher wattage output

So, just thinking about this.  I have an anker 14w foldable solar panel.  I like it, but it seems to not quite have the wattage output that I would prefer.  What if I were to make cable that would join these two usb output sources into one.  Same voltage of course, just higher wattage potential. Again, just an idea.  Thoughts?

Topic by n5yzv    |  last reply

Need help understanding LED drivers

Ok, I'm a newb to electronics and i'm having trouble figuring something out. Inspired by Dan's instructable, I decided to try and build my own headlamp. However, I've run into a problem. I have no idea what LED driver to use. I'm planning on using three of these bulbs, at 3.7v each and a max wattage of 4. I know if I rig them in series, the LED driver needs to be at least 11.1V, but my question is does the wattage of the driver need to be 12? Or should I rig the bulbs in parallel from my power source, and have one of each of these rigged to them individiually? Also, advice on whether it would be preferable to rig them in series or parallel would be great. Any help would be greatly appreciated. Thanks in advance

Topic by The Insomniac    |  last reply

Any help with my speaker building questions?

I'm not sure you'll be able to answer this. I was hoping to put one massive woofer (15") and send all low frequencies to it, and then put in two tweeters, hoping that it would somehow overcome the most likely overpowering bass. Is this a viable setup? Ideally, I plan on building these speakers for parties, where I just throw this in the car, drive there, and we're ready to go, don't need to deal with tiny crap speakers anymore. So, ideally, I want to create stereo sound on my tweeters, but just let it go for the woofer, since bass would obviously have no need for stereo. Would I need two crossovers, or just one? In my head, I imagine that I only need one crossover, followed by a stereo amp for the tweeters and a mono amp for the sub. I'm not 100% sure on that circuit though.I plan on using these parts:woofer:;=296-24635-1-NDwoofer amp:;=296-24635-1-NDtweeter amp:;=296-18033-5-NDSo, with that in mind, I'd love your help. Other Miscellaneous Curiosities:1) If you have any links as to where I can figure out the most audio efficient layout in order to achieve the best sound with this, that'd be a help too.2) Do I need a mid to help beat the woofer?3) In order to figure out the required power from the supply, I just need to add the max possible wattage from all the drivers, right?Thank you, Instructibles community.

Question by headinmysights    |  last reply

240v to 12vdc driver/transformer, what wattage output do i need?

I am trying to power 12no 3w 12vdc bulbs starting with 240v mains. i have found a 240v - 12vdc driver/transformer meant for LEDS but not sure what wattage output i need, 40w?

Question by ciderpig    |  last reply

What wattage laser would I need for engraving ABS plastic?

I want to build a laser engraver that can engrave ABS to a high enough depth that the grooves can be filled with resin. How powerful a laser should I get?

Question by JN8    |  last reply

What would be the average solar panel wattage needed for one person to live off the grid in a 32 ft. travel trailer?

Just want a ball park figure -- this would mean just simple living needs, not many electrical appliances (no A/C, washer, dryer). Anyone doing this who can give me an estimate? I know normally you would need to add up your wattage of usage, but I'm just trying to get feedback or an idea from those who are doing it.

Question by arnold54    |  last reply

What is the recommended speaker wattage rating (6.5" / 3 way) for a 4x45 watt RMS car stereo?

I am installing a new Sony car stereo and want to upgrade the existing speakers, I want to get the best compatible speakers for the stereo's wattage rating that will give me the best sound performance without overloading the speakers or having insufficient power to the speakers for sufficient volume/sound reproduction.

Question by PE_in_AZ  

How many wattage of solar panel I need to diy to charge 12 volts 70 amps battery? Answered

Kindly refer the supplied block diagram below.

Question by GearUp    |  last reply

How can I identify the power rating (wattage) of my scavenged resistors? Answered

I am currently making a mini guitar amplifier, from this instructable,, and i need a 1kΩ resistor. I have accumulated a few components by de-soldering and scavenging parts from old, and broken electronic devices. When I found out i needed a 1kΩ resistor, I looked up the ring code for that value and scanned over my broken electronic circuit boards to see if i could find a match. Which i did, but i do not know how many watts the resistor is rated at. The resistor in question is no more than 3mm in length. I know that quite a lot of resistors are more like 5mm in length. Can you tell from the physical size what the resistor I have is?(I will include a couple of pictures)

Question by mdog93    |  last reply


I want to basically go green (partially for my house)I figured out the following (Kindly correct me if I am wrong):I calculated the KWhs in following way:(Watts x nos x hours)/1000 = KWhs / day (Correct me if I am wrong)LOAD CALCULATION:Room 1 - - 5W LED x 4 nos x 4 hours per day = 0.08 KWh / day- 3W LED x 1 nos x 1 hours per day = 0.003 KWh / dayRoom 2 -- 5W LED x 2 nos x 4 hours per day = 0.04 KWh / day- 15W FAN x 1 nos x 8 hours per day = 0.12 KWh / dayRoom 3 -- 5W LED x 2 nos x 4 hours per day = 0.04 KWh / dayRoom 4 - - 3W LED x 2 nos x 3 hours per day = 0.02 KWh / dayTotal Consumption per day = 0.30 KWhs / DayNow, I calculated the number of solar panel required in following wayOn an average of 5 - 7 hours of full sunlight / day. On an average in this situation a solar panel will product approximately 0.007 KWhs.Therefor I assume I will require 43 Watts of solar panel, by calculating :0.30 (Required KWhs ) / 0.007 (KWhs / watt of solar panel) = 42.85 Watts (Approx 43 Watts)AREA REQUIRED TO PLACE THE PANEL:I got to know on an avearage 1 SqFt is required for 10Watts of panel.Threrefore I shall require 4.5 SqFt area to mount it.Kindly update me if my calculations are correct.ThanksDevNet

Question by dufferdev  

Power Tool Corded to Cordless

Hi 'nstructables I'm building a hovercraft (see several tutorials on Instructables - the one with a leaf blower) and my leaf blower is corded. I don't want to buy 25 miles of Black and Decker High Power Extension Cabling so I'm planning to convert to cordless. Here's my idea: (in visual) Is there anything I need to add? And if so, how do I make the "12VDC-240VAC" inverter described? My blower is 1600 watt. Thanks for any help! (Black and Decker)

Topic by nitrojon    |  last reply

Does the length of a fluorescent tube matter? Will a shorter fluorescent tube work in a longer fixture?

Assuming the wattage is the same. I have some 15" fluorescent tubes. Will they work in fixtures made for longer tubes if the wattage is the same?

Question by conrad141    |  last reply

Looking for a gainclone design that's lower powered than most. What is the equivalent wattage at 16 or 4 ohms?

Most of the gainclone designs i can find are between 25 and 50 watts. I have a pair of 20 watt maximum @ 8 Ohms which I'd like to build a small amp for (possibly portable, but gainclones don't seem to have much of that). The downside: I understand making the Ohms match the minimum required of my amplifier, but I've never had to worry about the max wattage before. I know that if I attach them in series I get 16 Ohms and 4 if parallelled, but trying to figure out what the wattage becomes seems difficult. I know its logarithmic, but I can't find a calculator for it. Plus I think it depends on the amp's output ability. (Yes I did mention these in another question.)

Question by Andale_The_Great    |  last reply

How do I go about connecting speakers with different wattage & ohms to the same source?

I have a bunch of old speakers that I wish to use for a project but I'm unsure if they will all work together. I have: 4 x 60W 10Ω 2 x 20W 6Ω 2 x 25W 6Ω 2 x 5W 16Ω with DC in & component input (out of old computer monitor base) Will I be able to connect all the speakers to the circuit board with the power & input? What will I need to do or obtain to make them work together?

Question by apple_juicy    |  last reply

HV fun

Any plans for a marx gen? can you post some pics? also what is the wattage of national lab,s "Z" machine? Just asking!

Topic by maker12    |  last reply

Laser Diodes? Answered

 So, I have 2 laser diodes, but I don't know what the voltage/amperage/wattage on them is. Anybody know how I could figure this out?

Question by iBurn    |  last reply

Do Resistors work the same on AC voltage??

This isn't for a project but I'm interested if resistors still work the same: Wattage, Resistance... Thanks :)

Question by Yonatan24    |  last reply

Can anyone tell me how to use a capacitor in a windmill?

I wouldlike to up the wattage coming in from my windmill to my batteries.

Question by swat420    |  last reply

Solar charging

Hi, pls suggest me for the following A 20Watt ( 20V , 1000 ma) solar panel is connected to charge a 12V, 80AH battery . What is the value and wattage of a Current limiting resistor to be added?

Topic by khhrao    |  last reply