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resistors and watts

I know how to use ohms law to calculate what size resistor I need but what I really need to know is how to tell/calculate what watt rating I need to use whether it be 1/4, 1/2, 1/8, 1,10 and so on.

Topic by pattyshaw    |  last reply


convert to watt?

I am thinking of buying a acid battery. Its specification says that it is a 12 volt one and it's AHC@20 is 200. Can anybody calculate the watt output. I am not sure but AHC stands for Ampere hour capacity. Thanks RajibAzam

Question by RajibA    |  last reply


5 watt LED

Hello, forgive me if this is not the right blog to post i was just not sure where to ask. i have a 5w led that came off a flash light i would like to either do my own flash light or install it in my house as a light, how can i do that and what do i need to power it, the only thing i know about the flash light is that is a 5 watt. also i dont know much about leds so if you guys can help that will be really cool. thanks

Topic by Nelson_Yepez    |  last reply


100 watt LEDs

Hi there I am wanting to drive 5 100 watt Cool white LEDs at half power total of 250 watts. Each LED spec is 32-34 volts DC @ 3.5 amps. Ideally I would like to drive from one power supply. or 2 at most, any advice would be welcome. please email me at tn21@live.co.uk

Topic by JohnT10    |  last reply


3000 watts inverter

Anyone knows how to build or make an inverter? a 3000watts inverter? can u give me the list of parts and picture diagram or schematic diagram? thanks guys

Question by dangzching    |  last reply


conversion ratio of kva : watts?

Question by lokoboy    |  last reply


4000 watts @ 220 volt?

How can i (step by step) generate 4000 watts and 220volt from a car alternator ?

Question by nicobotha12345    |  last reply


5000 watts power inverter

5000 watts power inverter with the circuit diagram using SG3524

Question by santos4eva    |  last reply


Please explain WATTS to me! Answered

 I know watts equal amps times volts. But why? What is the benefit? Hypothetically, I wanted charge a laptop with some batteries ( instead of with the charger cord). The charger cord says 65 watts or some such, but what does that tell me?  Is 65 watts the same as 13 volts at 5 amps? Or 13 amps with 5 volts? what voltage/amperage would I need to charge this laptop? Thanks!

Question by nepheron    |  last reply


Testing 3 Watt LED's

I recently purchased 13- 3 watt LED's. I'm trying to establish a high out-put LED light. I also purchased a LED Driver Transformer 48 Watt 120 Volt to 12v DC 4 Amp. First I would like to test each LED using the same divider. I'm thinking that if I create a voltage divider two 330 ohms to limit the current and reduce the voltage to about 6 volts that would allow me to test with the driver that I purchased. Secondly, will this driver be enough to drive all my LED's and would I have to reduce the voltage down too since it appears to push out enough wattage and amperage for the total number LED's I'm putting together? I'm building my circuit based on this video. http://www.youtube.com/watch?v=4qYZahe2s5o&NR;=1 Link to website data of 3 Watt LED. http://ledsupply.com/indusstar-1up.php Assistance would be greatly appreciated. Regards, 

Topic by lancruz    |  last reply


Testing a 3 watt LED? Answered

I recently purchased 13- 3 watt LED's. I'm trying to establish a high out-put LED light. I also purchased a LED Driver Transformer 48 Watt 120 Volt to 12v DC 4 Amp. First I would like to test each LED using the same divider. I'm thinking that if I create a voltage divider two 330 ohms to limit the current and reduce the voltage to about 6 volts that would allow me to test with the driver that I purchased. Secondly, will this driver be enough to drive all my LED's and would I have to reduce the voltage down too since it appears to push out enough wattage and amperage for the total number LED's I'm putting together? I'm building my circuit based on this video. http://www.youtube.com/watch?v=4qYZahe2s5o&NR;=1 Link to website data of 3 Watt LED. http://ledsupply.com/indusstar-1up.php Assistance would be greatly appreciated. Regards, 

Question by lancruz    |  last reply


LED 3 Watt Testing

I recently purchased 13- 3 watt LED's.  I'm trying to establish a high out put LED light.  I also purchased a LED Driver Transformer 48 Watt 120 Volt to 12v DC 4 Amp. First I would like to test each LED using the same divider.  I'm thinking that if I create a voltage divider two 330 ohms to limit the current and reduce the voltage to about 6 volts that would allow me to test with the driver that I purchased.  Secondly, will this driver be enough to drive all my LED's and would I have to reduce the voltage down too since it appears to push out enough wattage and amperage for the total number LED's I'm putting together?   I'm building my circuit based on this video. http://www.youtube.com/watch?v=4qYZahe2s5o&NR;=1   Assistance would be greatly appreciated.  Regards,

Topic by lancruz    |  last reply


Need a 30 watt "LASER"

Looking for an inexpensive laser cutting/engraving system. I will be taking it apart and  customizing it to fit onto another machine.  Currently, we have a rotating blade to cut sheets of material, but this set-up causes many issues.  A contact free solution would be best.  So I want to mount the laser carriage above the cutting area; the rest of the laser parts will be contained in a metal cabinet under the machine.  The laser would need to be able to travel 12-16 inches in 1-2 seconds and cut through 1-5 mil paper/poly material. I have a fair amount of experience with lasers, I have know how to sight them in and understand the technology.  We currently have 45, 100 and 400 watt galvo head lasers, as well as a 90 watt XY laser set-up. So, what website would you direct me to, to purchase an inexpensive laser system?

Topic by benjaminleebates    |  last reply


10 Watt LED Circuit

I am a software developer by trade and have little or no experience regarding LED and/or electronic designs. I am hoping someone here can help with a project I am working on using high brightness LEDs. I have studied several 'instructables' and specifically dan's "Circuits for using High Power LED's." My project consists of a few high brightness LEDs that will be placed in a high ceiling room with the brightness controlled by a microcontroller based on the light in the room (time of day, sun in window, etc). The microcontroller will use photocells to determine the brightness in the room and then adjust the LED using PWM pins. The LED is 10 watt and approximately 450 lumens. Attached is a circuit I drew as a starting point and would like help in determining if it will work, I am close or does it need to be trashed. I am not sure what the value for the resistor should be. Below are some calculations but not sure if I am on the right track or not. No need to be kind, I am more interested in getting it right and not losing any 'magic puffs of smoke' from any of the components. Here are the specs: LED IF: 1.6 A Peak Forward Current: 1.7 A Forward Voltage: 8 V LM350 (heavy duty version of LM317 IO_MAX: 4.5 A 1.2 - 25 V adjustable regulator BC337-40 Collection Current - Continuous: 800 mA dc Total Device Dissipation: 625 mW Resistor: 5W or 10W Voltage Amp Ohms Watt 8 1.60 5.0 12.8 8 0.80 10.0 10.0 8 1.10 7.5 8.5 Note: LED and components will have adequate heat sinks.

Topic by desnotes    |  last reply


Does anyone know the current best LED for Lumen vs. watts?

I would like to get a few of these for a project. It would be nice if there is a ebay seller that can give a deal. there was a guy that found this out, but that was a year ago.

Question by JZ Price  



How do watts, watt-hours, etc. relate to voltage, current, and resistance? Answered

I've worked with 12v and 5v a fair amount, and I've got a good understanding of Ohms law, series and parallel circuits, etc. But, I get a little sketchy when it comes to wattage ratings, KWHs, etc. and their relation to (now) my electric bill, (but hopefully soon to my off-grid, alternate power sources/power banks) and what I can handle as far as power consumption, etc. Any theory, links, book suggestions, practical examples, etc. will be GREATLY appreciated. Thanks so much in advance, everyone!

Question by sykotik    |  last reply


KWH , Watt giving me a headache...

Morning Guys Need a bit of help with the maths. Hoping to run a fridge on a inverter / battery / solar panel. If it has a energy consumption of 0.43 KWH, I think it would be about 43 watts not sure here. What size battery and solar panel would I need? Big Love Chris

Question by Handyperson1    |  last reply


I have 2 questions (in details) First: a way to measure Watts? Second: Rotating Camera Mount?

so as I said I have 2 questions. First: Is there a device that can measure the watts of an appliance? I just got a hold of a cheap generator (900w normal 1000w peak) and need to find out the wattage of some appliances. (None have stickers/plates on them at all to help me calculate it.) Second: Can anyone direct me to an instructable on motorized rotating camera mounts or anywhere that can show me how to build one? I want to be able to watch the sky from inside we get some nice weather here but hard to watch it from inside hehe.

Question by BlueSuneLIght    |  last reply


how many watts and hp can?

Question by tazerl494    |  last reply


LED help!!

Hello, forgive me if this is not the right blog to post i was just not sure where to ask. i have a 5w led that came off a flash light i would like to either do my on flash light or install it in my house as a light, how can i do that and what do i need to power it, the only thing i know about the flash light is that is a 5 watt. also i dont know much about leds so if you guys can help that will be really cool. thanks

Topic by Nelson_Yepez    |  last reply


What is a 1/4 watt resistor? Answered

Alright, So I know the basics about resistors and what-not, but as I was buying beginner supplies, I noticed there were resistors in OHMs and Watts, What's the difference between the two? And like, can the unit Watt be transfered into OHMs? And which one would I use when my general area of working would be around basic LED work and noob stuff like that xD?

Question by E D E N    |  last reply


20 watt PA amp transformers.

Today I bought a 20 watt PA amp at a garage sale for 5$, and there were 2 big transformers in there. Any ideas of what I could make?

Topic by mrbubl3s    |  last reply


MXDL 3 watt joule thief? Answered

Can anybody make sense of the joule thief inside a MXDL 3 watt luxeon torch? I can post a rough picture of it if needed.

Question by .Unknown.    |  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


100 watt sub woofer amp

I'm looking for or to make a 100 watt amp, I can't seem to find any. If you know where i can find one online or a schematic to build one please let me know! Also is it possible to resist or lower the amps from an amplifier or will I have to specifically get a 30 watt amp for the mid range speaker. I am attempting an "led music box on steroids" project hahaha.... basically what I am going to do is make a clear plastic box and put leds and speakers and a 6" sub in it. Kinda bored and looking for a fun project and this came to mind. I'm open to any suggestions to make it better or ideas on how to power the speakers. Thank you in advance! The sub woofer I'm looking to power http://www.electronix.com/100-watt-woofer-speaker-ohm-p-13521.html and the mid range speaker http://www.electronix.com/30-watt-midrange-speaker-p-13507.html Might think about putting a tweeter in too

Topic by zcm87    |  last reply


How do you work out the wattage of an amp?

I made the Ruby amp by runoffgroove (http://www.runoffgroove.com/ruby.html) 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


using 1 watt LEDs with a 4017

I want to build a chaser type light array using a 4017 counter divider circuit, 555 timer and the ever popular 1 watt luxeon LEDs, but I don't think that the 4017, or the 555 can withstand the current that will be going through them. I know in most cases you can simply toss a heatsink on the component and it will be fine, but I don't know if this will work with the ICs. https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId;=10001&catalogId;=10001&productId;=12749Here is the spec sheet for the 4017. Thanks

Topic by John Culbertson    |  last reply


Generating a Couple of Watts Using Urine?

Hello, I recently came across a paper written by a researcher from a Scottish University about generating electricity directly from urine in a fuel cell and I was wondering if a larger version could be built to generate around 2 watts.  The power per square cm is around 1.5mW so even at 1mW I would need 2000 cm-sq so I think it would be easier to build a stack of cells instead of one or 2 large cells. I'd like to attach the paper but it's one which you need to pay for though I got it for free, could a moderator let me know what to do?  It was written by a Shanwen Tao and called 'A Direct Urea Fuel Cell' DOI: 10.1039/b924786f Another idea I had was to use a small PV setup to generate hydrogen from urine and then store the gas so that it can be used in a hydrogen fuel cell.  I've had some difficulty in trying a to find a cheap fuel cell but then I came across this page: http://www.mtmscientific.com/fuelcell.html Are there any really simple ways of building a fuel cell? I'm posting this here to see if anyone can help me come up with a viable design and maybe even build it for me.  I can pay you for your time and effort; though as a student I do have a tight budget to stick to. Any help, advice and ideas will be very much appreciated. Thank-You

Topic by jezym108    |  last reply


8 Watt Guitar Amp Help

I've been fartin around with electric and acoustic guitars for about the past 5 years. Only now am i getting decent (by no means good, but better, i guess...). I've been wanting to make a small amp with a small speaker for some time now.I saw this circuit the other day. Its VERY simple.http://www.aaroncake.net/circuits/amp.aspIt says to reverse the values of R1 and R3 for use as a guitar amp. there's some other stuff too. I was going to see if i could pick the stuff up at radioshack tomorrow, and maybe make it an after-work project for the week. Maybe cut up some wood and make a nice box for it. 1)Do you think these parts would be available at radioshack? and what do i need to look for if i cant find the exact IC? 2)Any special soldering tips? 3)What kind of pot do i need to add, and where, for a volume knob?4)Is there any extra things you think that needs to be added?5)Are those triangle things grounds? as in 12v negative? And what about the other wire from the guitar? 6)Also, what ohmage speaker do i need to use? What am i looking for in a speaker?7)Will 8 AA batteries do the job?8)Do i need to add like a fuse or something somewhere? Going straight into the IC...i dont know. If anyone knows of simpler or better designs, let me know. I seem to really [insert proper four-letter word here] up electronic things. I think thats all the questions i have here. To respond you can just go like..1)i think that....like that. Hopefully that will make it easier to answer all my ignorant questions.Thank you!Jason(sorry if i seem like a a$$ here. Its 1:35am, I've been looking this stuff up for two hours, and i dont feel like i got any further....)And since i dont have a suitable picture, have yourself a look at my LEGO steam engine: (after the third try of trying to post the video with unsuccessful results, i realized that i was posting the embed code int eh URL place...need....sleep....)

Topic by John Smith    |  last reply


What is the maximum power (ohms/watts) available from a headphone port?

I happen to have a set of 8 ohm speakers (which say 20 watt max) and wondered about using them so I can listen to my mp3 player in the shower.

Question by Andale_The_Great    |  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


wattage

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


transformer input Answered

I have a transformer with 13v input can i give it 240v without it melting and can you please tell me the math of transformers  am new and any information helps

Question by mohamed amin    |  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


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


Is it true? 2 watt led has 1 diode, and 3 watt led 2 diodes? Answered

Is it true? 2 watt led has 1 diode, and 3 watt led 2 diodes? or can a 3 watt 700ma have both?

Question by MistaMasta    |  last reply


I have a simple question about watts... Answered

Watts = amps times volts, correct? So if I had a laptop that charged with a 60 watt power supply, could I: -Charge it with 10 amps at 6 volts? (that is the same as 60 watts) -Charge it with 6 amps at 10 volts? (that is ALSO the same as 60 watts) -Charge it with 5 amps at 12 volts? (that is ALSO the same as 60 watts) -ect... Watts is just how much 'energy' passes a single point every second (or whatever), so it doesn't matter how you get the watts, watts is still watts? I'm still trying to grasp the whole concept of watts, so yours answers are infinitely appreciated!!!

Question by nepheron    |  last reply


1 watt Frequency Doubled Violet Laser

I want to make a 1 watt violet laser, by using a 1 watt 808 nm laser and channeling the laser through a KTP crystal. Judging from my humble knowledge of second harmonic generation, That should create a 1 watt violet laser beam. Correct?

Topic by Nexoid    |  last reply



how does a kill a watt work exactly?

Hey everyone i was just wondering how watt meters work. most of you already know the Kill-A-Watt. this is basically what i am looking to understand. Kill-A-Watt may get a little complicated as a device, but i would like to know what the basic idea is behind the meter.is there an instructable on how to make your own simple meter? any help is greatly appreciated. thanks

Question by mohissa    |  last reply


Tweet a Watt now works with Google Powermeter

The Tweet-a-Watt is a cool hack that was made by Adafruit (Limor Fried and Phillip Torrone). It would tweet your energy usage from one outlet so you could be more aware of how much juice you're pulling through the lines. Now you can connect it with Google's Powermeter and get some nice graphs of your energy usage. Hit the link for more info and get the code to do it yourself. Tweet-a-Watt now works with Google Powermeter!

Topic by fungus amungus  


stereo plus amp is how many watts?

For instance if my stereo is 20w rms and I put an amp of 45w rms will I have 65w rms?

Question by RichardB263    |  last reply


How to power 8ohm 1 watt speakers?

I'm working on a project for school that consists of a wireless speaker. They will be mono speakers.  I have an 8 ohm 1 watt round speaker. I would like to power these.  I've read on lm386 and tsa7052 ic to do this. For the wireless I was going to use dexdex's instructible bluetooth headset hack I'd like to power it all with a 9volt or a lithium hacked out of old product. Are there any things i should know for the amplifier in relation to the type of speaker i will be using?  Will i be able to power the bluetooth headset and the amplifier from the 9v? thanks for your time!

Question by williamhaze    |  last reply


What to do with a 45 watt solar panel?

I have 2 solar panels 1 is (15w) and the other is (30w) they both produce around 3 amps together in good wether Anyone have some good ideas on what to power with it. it is charging up a 17ah battery

Question by Daniel Deacon    |  last reply


What's the Difference Between Watts, Amperes, and Volts?

I always find this really confusing. Also I have a MotoMaster 12v solar panel supposedly for a car or something from Canadian Tire but I got it for electronics projects. I can get a voltemeter to detect voltage coming from it but I can't get it to work a motor or light or anything. It has two normal alligator clip leads.

Topic by Aeshir    |  last reply


50 watt electric and bass guitar amp?

Good day to all, i'm new to this site hope i can gain more knowledge in electronics here, since i have been doing alot of programming lately.. i am planning to build my first higher wattage amplifier for both guitar and bass, i already have built smokey amp and its other cousins like the ruby amp and some guitar effects. i will build the two amps simultaneously and put  it in one housing.. the speakers will be separated and also the circuits and all.. does any one have schematics for this kind of amplifiers?? it should bea solid state amplifier, because its hard to find tubes here and also it is expensive.. correct me if i'm wrong 1. "instrument >>>preamp>>>poweramp>>>>speaker" ? 2. is it possible for example to use a smokey amp as the preamp section and connect it to a 50 watt power amp? 3. what type of speaker should i use for the guitar and for the bass? should it be a woofer or sub-woofer? coz i dont have a clue on speakers.. tanx in advance..

Question by VAustin89    |  last reply


Do Amps matter?!?

Ok, I need a charger for my motorolla two way radios. I have the dock, only need a DC power supply. on one of them it states "18Volts DC +/- 20%, 15.3 watts" .Lets say I get 18VDC 1amp power supply, that's 18W,it means it's an overkill? or 15V 2Amps? As I understand, usually amps don't matter, as the item draws as much as it needs, but since it is a charger.. Cheers for the teh help!

Question by zhgutas    |  last reply


Does my garden 250 watt AC/DC transformer consume 250 watts when I only have 50 watts of DC LED lighting?

So the question is:  Does an AC/DC transformer consume its max wattage even when it's not maxed out on the DC side?  I have a 250 watt transformer that steps down to 12V for low voltage garden lighting.  Is it always drawing 250 watts?  Added up, I have about 50 watts of LED low voltage fixtures. Back in my military days, when we were in Europe, we had these 300, 500, and 1000 watt transformers to step Europe 240V down to US 120V, and we were always told those transformers drew their max capacity even if a small radio was plugged into it. I argued it prolly didn't because of the conservation of energy thing. I can always put a kill-a-watt meter on it too I guess. Thanks in advance!

Question by SeanW65    |  last reply


Airbrush compressor TC-20, how many watts???

Hi guys, i recently bought a mini compressor for cake decorating. Its a "ABD TC-20" and i bought it at TCPglobal. Problem is, i dont know how many Watts it uses! You see, i bought it as a pressent for my wife. "Nice? Yes!" "Bought with my nose and not my brain? Yes! Im living in Holland, and our network works on 220volt at 50Hz. The compressor i bought works on american standerd, 110volt at 60hz. So i need a converter to make the machine work without frying its circuits... If i buy a converter specificaly for this machine, it has to have the right amount of Watts. i know, i can buy a converter that handles Watts in the range of 1000Watts, cuzz more watts on a converter is better, but than i'd have to buy one thats quite expensive. Because if the compressor only uses, lets say, 50 watts, i could buy one that has a max of about 100 / 150 for a waaaay lesser price than the one thats more powerfull. It would be 50EU for the smaller converter against 200EU or more for the bigger one. So, if you happen to know something on this subject, i would be more than happy with any info you've got ;-) greets! P.S. At the moment i wrote this, the package is stil on its way from america to my house. So i dont have a box or machine sticker to sneak the info i need from...

Topic by AriedeB    |  last reply