How To Calculate Leds Resistor needed and ohms law explained!

[cameramandanno]

Thanks for the crash course in ohms law. Now I feel more of a dumb ass for catching on after the first 10 views of this vid.

[DIYElectronics]

@cameramandanno Thanks, I wish it would not of taken ten views. I may go back a remake this video a bit clearer. I guess you got the point though. 

[DIYElectronics]

@lorenzog4545 To your comment on how .02 or 20ma = 150ohms because i was saying at 5:55 that you divide 3v by 20ma or 3v/.02 which = 150ohms the resistor required to run a led that drops 2v and uses 20ma of current

[moto123cross]

* Emitting Color: Red * Intensity Type: 120-130Lm * Viewing Angle: 120-140° * Forward Voltage : 2.9V~3.3V * Forward Current: 750mA * Wavelength : 610nm-630nm * Emitting Color:Blue * Intensity Type: 120-130Lm * Viewing Angle: 120-140° * Forward Voltage : 3.5V~4V * Forward Current: 750mA * Wavelength :460nm-470nm Emitted color: White DC Forward Voltage(vf):DC 3.6～4.0v DC Forward Current(IF):680-700mA Viewing Angle:120 Degree Luminous Intensity:165～180Lumen

[DIYElectronics]

@moto123cross Okay, so you got 2 different types of leds so we are going to need to different resistors to run the led's, so were going to assume your power supply puts out 30v steady, next assume your led's are in parallel with a resistor attached, now we need to figure out what resistor we need for the 2 different led's. Lets assume the red led drops 3v and pulls 750ma so use the formula Resistor = (30v - 3v)/750ma This means u need a 36 ohm resistor for every red led

[DIYElectronics]

@DIYElectronics To supply with it the correct current, now with the white led you would set the formula up like this Resistor = (30v - 3.8v)/690mA, this means u need a 38 ohm resistor, You could prob get away with running all of the led's off of a 38 ohm resistor the the blue and red leds might not be as bright as they could be. one problem with this is im assuming that the led power supply is producing 30v, if it it producing a high volt u will need bigger resistor

[DIYElectronics]

@DIYElectronics so basically when u get your led power supply, your going to need to turn it on, and test the voltage its producing, and use this formula to solve for ea resistor for the leds, Resistor = (Power supply voltage - voltage drop of led) / Led forward amps Remember this is amps not mA so u have to convert, ma to amps, 750mA = .75A just move decimal point over to the left 3 places.

[moto123cross]

@DIYElectronics ok but look at this video the guy dont put any resistor and its work

/watch?v=yy62DdNpsqc and this too /watch?v=4qYZahe2s5o

[DIYElectronics]

@moto123cross Alright listen, ive explained it to many different ways, i watched the video, he doesnt clarify which power wire coming off the power supply he hooked his set up to, he could of hooked it to the 5v led coming off the power supply or the 3.3v wire who knows, he did not sound to educated in electronics, more in growing weed. if you are using a 30v power supply u need a resistor thats the end! now the resistor wattage needs to be figured and watts = Vd * Amps

[DIYElectronics]

@DIYElectronics so using the red led from my past post, the resistor is going to need to drop 27v at 750mA so 27*.750 = 20.25 watt resistor, BUTT if you were to use a 5v power supply, u would only have to drop 2 volts at 750mA so 2*.750 = 1.5, so you could get away with a 2watt resistor. You need to look up electrical laws to understand these principles there are 2 laws id look up, ohms law, and the power law. to understand why things are the way they are.

[moto123cross]

@DIYElectronics the problem is how i can make all this im not an expert and i dont understant how to put the resistor and how many i need because at the begining i was thinking that i just need my 30 X 3 watt led and connect them in parallel on my led driver but its not simple like this if you make a simple video on this im sure you will have alot of view because so many person search how to do that. I know you are very good in electricity and led but for the other people its hard. Anyway thanks

[moto123cross]

@DIYElectronics ok but look at these video the guy dont put ny resistor and its work

/watch?v=yy62DdNpsqc and this one too /watch?v=4qYZahe2s5o

[moto123cross]

Hello man can you designe me a 400 watt led light please with all 3 watt led but i dont know how much and wath ohms so can u help me please?

Great video very interesting

[DIYElectronics]

@moto123cross what type of led is it, whats the running voltage? if the led is 3watt u cant make it run 400watts, with 3 leds all pulling 3 watts it would be a 9 watt led setup.

Remember Watts = Volts * Amps so For a 3 watts led if it ran 12v then it would pull around .25 amps. Just wire them in parallel (means All the hots connected and connected to hot, and same with grounds all connected and connected to ground) and you will get maximum power from your leds. Thanks

[moto123cross]

@DIYElectronics hello so i have a 100 watt high power led driver with 10 X 3 watt high power (blue), 10 X 3 watt high power (red) and 10X3 watt high power (white). So my question is if i can mount all this led on my simple 100 watt led driver and how i make good circuit

thanks for the answer

[DIYElectronics]

@moto123cross Well if you do that math you would be right at 90 watts so id say would would be fine,  remember follow instructions of your led driver, but if it doesnt specify which way to wire led's, wire them in parallel and fire it up see what it looks like. do you know the voltage these are suppose to run at?

[moto123cross]

@DIYElectronics so my idea is to put 6 row of 5X 3 watt led in parralel

with the 100 w led driver

to see the driver go to ebay and write 100 watt led driver and it's the 25 $ one

thank for the answer

[DIYElectronics]

@moto123cross okay, well your going to need to add a resistor to bring the voltage down to your leds operating voltage because that one is from 28-36v which will burn up your leds, basically the led driver is a power supply, thats it, so you need to use the forumals in this video to help to calculate the resistor needed, and since your pulling so many watts your gonna need a big power resistor to bring the amps down and voltage

[DIYElectronics]

@DIYElectronics you could use an adjustable volt regualtor to accomplish this, and then just add in a resistor to limit current flowing to your leds, id start off with a bigger resistors and work my way down if you do not know the specs of your leds, and i would just assume your leds run off of 3-5v unless you know the true specs. hope this helps

[moto123cross]

@DIYElectronics and i cant make my circuit without resistor because in video on youtube the person just need a power suply he dont add any resistor

[DIYElectronics]

@moto123cross well if u apply that voltage and amperage to the leds they will blow instantly because there is no resistance in the leds, so amperage will sky rocket and burn out led. because Amps = Volts/Rest.

[moto123cross]

@DIYElectronics so you say i need a one 100 watt power resistor and how i plug it seriously can you make me a draw of all that and send me to my adress spider_man_123_3@hotmail.com please

thanks for the answer

[DIYElectronics]

@moto123cross i cant answer your question, because i dont know the voltage of your leds, nor the amperage they require to run. you need a datasheet for them. once u have datasheet make sure u stick to datasheet, and supply the right voltage and amperage

[moto123cross]

@DIYElectronics so you say i need a one 100 watt power resistor and how i plug it seriously can you make me a draw of all that and send me to my adress spider_man_123_3@hotmail.com please

thanks for the answer

[lmrproduction]

AWESOME! Thanks a lot and will be watching your future updates. Good day!

[lmrproduction]

Thanks for your response. I didn't know what I was talking about. Anyway, Im trying to connect my gas and pedal LED lights to my car. I want them to light up when I put the key to d ignition. I can do that by tapping into the FUSE box & accessing the ACCESSORY Fuse slots. Since the Pedal lights come w a resistor box (?) that is suppose to plug directly to the 12V battery, do u think I can tap into the 20Amp Fuse slot and give me the right amount of power to light up the brake and gas pedal LEDs?

[DIYElectronics]

@lmrproduction Okay after reading your comment a couple times i think i got what your trying to task, you want LED lights that u put on your gas and brake pedal to light up when u put your key into the ignition? Well i asuming you already have a led configuration built but only need power for it. What i would do is tap a 20amp line that is always on when the ignition is on, one example would be the radio. and as for the "resistor box" as you call it, its imporant because

[DIYElectronics]

@DIYElectronics It controls the amount of amps going to the leds, the led arnt going to pull many amps at all, so if you connect the resistor box to the radio accessory wire so the leds only come on when the key is turned on you will be in business!! hope this helped out.

[lmrproduction]

Are you in Electrical Eng. course or Electronics? Great Vid. Im trying to figure out the Amperage equivalent for 12Volts... I think I got it? Can you tell me just to check myself?

[DIYElectronics]

@lmrproduction Im in a Electrical Eng course, but as far as your question amperage depends on the load applied to the voltage so amperage = voltage/resistance. You have am maximum amount of amperage you can produce at a certain voltage. What are you trying to test? for liek a power supply if i wanted to test what kind of amperage i was producing at a certain voltage with a certain load, i would connect a 10omh power resistor to the power supply and measure the voltage drop then take v-drop

[DIYElectronics]

@DIYElectronics and using ohms law with the v drop and resistance of the resistor to figure the amperage going across the load. Alot of people try measuring amps by shorting out power supply but this is a amp with almost no voltage so its not a good way to test. 

[FABRIC8TIONUNLIMITE1]

Question: I have four LED's w/ forward voltage 3.2 ,max voltage 3.5V reverse voltage 5V, peak forwd. current 100mA , wattage consumption 0.064 , I want to use in a car so I have 12 V Batt. for power. I think I need two 1w 56 ohm resistors with LED's wired in series. Will this work and where do I put the switch ?(switch is factory 12 V) and will the switch work with this? Any help would be appreciated.

[DSMANDARIN]

TI-83 Plus sighting at 13:02

[DIYElectronics]

@DSMANDARIN Yep, i love my ti-83~

[iluhanutij]

you roar haha!

[tannerhughes11]

really not trying to be a dick, but were you hung over when you made this? great video, very useful, you just sound like you had a good night lol

[DIYElectronics]

@tannerhughes11 I actually made these videos so i could better understand what i was learning in school, and i was really tired, and studying for a test. lol. I wish i was hung over!

[billhead1]

I like your multimeter. What brand/model is it?

[DIYElectronics]

@billhead1 umm EQUUS 3320, but ive since upgraded to Fluke 289 Rms meter its got alot of more advanced features but comes at a price!

[jessiejv9]

how does on led change color

[DIYElectronics]

@jessiejv9 dont quite understand your question. u cant change the color of a led unless its a rgb led which has 3 leads

[jayson01982]

how about im using telephone, and 12 leds in the board in series, how hshould it glows in brighter?

white leds?

[jayson01982]

how about im using telephone, and 12 leds in the board in series, how hshould it glows in brighter/?

[ecopegasus]

Milli is thousand, not million.  Nice video

[platinumtoast99]

Great Job on the tutorial. You are the first one that made it a lot easier to understand, Many thanks.

[NPP83]

Great explanation. Love the thumb-coverup-and-solve-for technique.

[ivangohome]

Like the way he covers all aspects of hooking up a LED. I like the sound quality unlike most others.