This is THE BEST tutorial video of this subject! I hope you make more of these! The whiteboard, clearly drawn and written and spoken at a calm pace, the perfect combination! This setup works perfectly for teaching purpose!
I have struggled for years! trying to figure this stuff out. You single handedly demonstrated this better than anyone, and simple enough where I now understand it. I have been thunking my head over this so many times, but now I did it one last time because it was so easy to do and makes more sense than ever before. Thank you.
Its simple. Just check the voltage drop of the LED and calculate the resistor value for 10mA current. For indicators even 2 mA current is enough. Even you dont have to be exact, just find nearest value of resistor you calculated.
Sounds like you are missing the most basic of electronics skills. You should have bought and read a basic electronics book for $10. Then you would have known in an hour or two and not years.
You have done a superb job of explaining and illustrating the basics and managed to clear up a number of questions I had concerning led's and resistors and such. I've always been curious about basic electronics but never really pursued the topic in any real depth. I have done a bit of basic house wiring, but this stuff is new to me and looks like fun. The winters here are cold ... and longish. Thank you. I really appreciated your laying out each of the formulas.
I would just like to say.....that was the most simple way of explaining the triangle....when I was at trade school doing my electrical apprenticeship...at the start the way this was explained was so SUPER CONFUSING MY HEAD WAS GOING TO EXPLODE...🤯 SO HATS OF TO YOU ON A SIMPLE WAY OF SHOWING A WAY THIS ALL WORKS....I WISH I COULD HAVE BEEN SHOWN THIS BACK IN THE DAY....WELL DONE...👍
Hey, youre so nice and teaching this as simple as possible and taking it slow... it ecourages me, a commoner, to study this. I always thought I would never get it, but now I actually do. Thank you Sir
I really appreciate you making this video. I'm 70 and just now getting into messing around with LED's and breadboards etc. Much of the I R V triangle is still a bit of a puzzle to me and hopefully this old brain will eventually learn to correctly apply the appropriate formulas where needed. I have no idea how far I'll go with this stuff but it's pure fun for now. Thanks again. Scott
Good for you, hmmm, um put your finger over the value you want, so if its V then IxR, if it is if you want Current (I) then it's V over R (V/r or V divided by R) because V is over R. Sorry didn't watch the vid maybe he/she says this. Then you have Watts so P Power (at the peak of the triangle) = I x V. Type in Ohm's Law to your browser then go to images and you should find a wheel image that uses more conventional maths. Stops my brain falling apart like a chocolate orange. You'll get the hang of it. :) Many electronics shops have them as a bookmark. Such as I=√P/R..... Hi from Oz.
Very good show for this 62 year old that’s adding some electronics related improvements to his model railway! You are an excellent instructor, and provide tons of information in an easy to comprehend way! Thanks! Subbed!
Thank you very much Tom. If I had more room I would love to build a model railway but there is not enough room to swing a cat where I live. Best wishes
This simple tutorial really helped me understand how to put some electronic components work together in a circuit adhering the best practices as in my case I am a visual learner. More video like this please.
Good video. Takes me back to my Signal Corps radio school days; we spent a lot of time calculating circuits using Ohms law. This was years before calculators were available- man, they make electronics SO much easier!
Thank you for this. I'm a novice amateur in electronics and had been wondering how to determine what size resistor to use. Your Examples make perfect sense to me.
Bought some 5050 SMD LED's for a project and this was valuable information. Never really got into RGB's that much so I'm learning from videos like this. Thanks for the info, you helped me more than you know.
What a fantastic video. I have been struggling with wondering if I had to add the total Vf for led's in parallel or series. I found your vid by accident and it has saved my sanity. Thank you for uploading it and you are a great teacher.
Never have been in any electronics class in my life, you made this very easy. I can say, I just got my first crash course... Thank you sir... I love messing around with electronics, yes did made some messes before, but am still here... 😂😂😂
cant thank you enough ive asked and read but couldnt take it in you explain so well that ive finally got it thank you from all our beginners we will get there in the end with teachers as good as you are colinxxx
Vary good video. I learned more from your video on LED circuits then other videos I have watched. I was hoping to see more electronics videos but found they're mostly musical instruments.
Splendid, simple instruction. Much appreciated! If I have a higher voltage source, say 12v, will a larger resistor mitigate the potential burn out? Ah! You’re well ahead of me.
Exactly what I was looking for. Graduated electronics tech course nearly 40 years ago and infrequently used the info. Knew what I was looking for to refresh my memory but couldn't find it till now. A near perfect presentation. Thank you. I recognized the Ohm's law triangle and knew where you were going with the power calculations so I could follow but would have liked to see the P - I - E triangle as well just to be sure I was remembering it all correctly. Also, I was a bit confused at 19 min 41 sec into the video I read "This example would be less efficient than the previous example of running the LEDs in parallel". Wasn't the previous example in series? Sincerely not busting your chops, I just need to be sure because I'm easily confused.
Hello. firstly thank you for your kind comment, I must rewatch the video and have a look at what I said at 19min41s . I made this video a while ago and cannot remember what I said but I have made mistakes before in other videos so I may be able to add some text on the video to correct any mistake or if not place it in the about section under the video. thanks for pointing this out to me. best wishes.
There is a typo on the screen. The LEDs are in parallel and each want to take 20mA , whereas the previous series example they were sharing the same 20mA. LED (indeed all diodes) should not be connected in series like this a fraction of a mV difference is all that is needed for ALL the current to go through ONE LED and cause it to very quickly fail (sometimes dramatically). The better solution is to add a limiting resistor in series with each diode and break the relationship. Use the series configuration if you have a lot of voltage and the parallel if you are running from a low voltage. Efficiency of design is also understood by looking at the power wasted by the LED, you obviously want that to be as small as possible
@@deansmith4752 You mean "all diodes should not be connected in _parallel_ like this ..." and that's because whichever diode is taking more current, it will heat up more and its negative temperature coefficient will cause it to draw more of the current, and so on. The power consumed by the LED is fixed for a given brightness, so the efficiency is governed by the power wasted in the dropping resistor (not the LED). To maximise efficiency, you want the supply voltage not too far above the on-voltage of the LED, but that makes the dropping resistor small and can lead to greater variations in current consumed for changes in temperature or variations in samples of the LED.
@@RexxSchneider I'd say you're both right. To summarize it; a series connection *guarantees* that the same amount of current (A) runs through each LED. A parallel connection of LED's *guarantees* that the same voltage potential is applied across them. LED's are inherently a bit "tricky" in ohm's law, as they don't follow a linear relationship between voltage and current since it's an "active component", being a semiconductor. Since ohm's law doesn't really work on active circuits, we have to use static/idealized values for semiconductors. LEDs, and regular diodes for that matter, are simple enough since when surpassing their forward voltage, (or reverse breakdown voltage), they'll be idealized as essentially having resistance that IS the proportional of voltage and current, and likewise, when below the threshold, we could in a way say the resistance is infinity. But naturally a LED that's ON will heat up, and that's the culprit that makes LEDs so "hard to calculate" with Ohm's law, cause that changes it's forward voltage. The hotter it gets, the lower the forward voltage gets. So dean is correct in that when LEDs are in series, one single LED with different forward voltage would drop less voltage, allowing more current to pass in total, and also leaving more potential for the next LED. It should be noted that the next LED would then sink more total power, decreasing it's forward voltage faster than the first, and kinda "balancing" it out. The solution proposed isn't in effect changing this fact, but does make it look a lot easier to calculate individual LED in a diagram. I think what Dean meant by "current to go through ONE LED" was that one led would drop all the voltage, in effect "consuming all the current", since the current would be the same across all LED's in series what. (disregarding inductance etc.) Rexx is absolutely correct that LEDs shouldn't be connected in parallel, but the "like this" doesn't show in the video, since they all have a limiting resistor. But if the LEDs were indeed in parallel, this is when Dean's comment would happen. One LED would be a fraction out (inevitable) of the forward voltage of the others, thereby making it drop less voltage and in turn let more current flow. This is thermal-runaway waiting to happen, as that LED would consume more power, getting hotter, dropping even less voltage but passing even more current. I wouldn't say that "the power consumed is fixed for a given brightness", since brightness tends to get weaker when over-driven (more power used for heat than for producing photons). But I get the idea. The reason a parallel circuit could be stable a while with very similar LEDs, is that power consumption is equal to voltage times current. A LED is dropping less and less voltage, but taking more and more of the current, making it effectively use close to the same amount of power. But when it drops enough voltage to drag another LED into it's forward voltage threshold, that other LED is drastically affecting the total current in the circuit, since it's basically "turning off" letting all it's current flow through the other LEDs. This is when they'll get over driven and blow. (sometimes dramatically) ^^ So to summarize: use a LED driver to maximize efficiency. It changes voltage in accordance with current drawn, thereby limiting the total current and not exceeding the rating of any LEDs, and use a resistor as a "current limiter" that would account for a certain drop in forward voltage. It's easier, but simplicity has it's tradeoffs. Wow, sorry for the wall of text... I got on a roll there..
@@arsenic1987 You have a decent grasp of what is happening when diodes are connected in parallel, but underestimate the effect of the exponential relationship between voltage and current. When you say, for example, _"A LED is dropping less and less voltage, but taking more and more of the current, making it effectively use close to the same amount of power"_ you miss the point that a forward voltage increase only needs be around 20mV to produce a doubling of the current through it. That's equivalent to as little as 10°C rise in temperature. That means that the power consumed by the diode (or LED) does increase quite dramatically as its temperature increases; the increase in current is is far greater than the minute change in forward voltage. It definitely does not _"effectively use close to the same amount of power"._ The whole point of the dropper resistor is to stabilise the current against changes in temperature since an increase in current as the diode heats up will cause more voltage to be dropped across the resistor, thus reducing the voltage across the diode and significantly reducing the increase in current because of the exponential relationship.
First of all english is not my mother language, even that i've fully understood ! Why you was not my teacher 60 years ago?! Thank so much for this clear and fully understandable explanation. Regards from burgundy. ..
2:19 - We learned the formula as U = R * I. I've never heard of voltage referred to as E. Unless talking about the underlaying electric field vector, but in that case (even though analogous to voltage potential), the whole formula is replaced with "Electric field vector = amperes pr unit area * resistivity in ohm-meters".. Apparently, the U is used only because the names of quantities should not be the same as the unit name itself. (Ampere = unit, I = amount of Amperes(A). Ohm(Ω) = unit, R = amount of ohms(Ω), V = unit, U = amount of Volts). So it's just a note for English speaking countries. (U = RI) is the equivalent of (V = IR). U or V = tension or potential. I = flow or intensity, and R = resistance. Respectively measured in units of Volt, Ampere, and Ohm(Ω).
Thank you for a very interesting video and the careful way in which you told us what has been puzzling me whilst experimenting with LEDs. Can you please say if it is possible and how to calculate the requirements of an LED that has not got a data sheet? Many thanks Benters
I went through an Air Force tech school back in 1976. I understand everything you explained. Well done. But, I've gotten a little rusty over the years. One day I got a phone call from my son who worked at Circuit City as an installer of various electronics. He had a question which made me re-think a simple series circuit. He had an LED that runs on 5 volts that he needed to install into the 12 volt car. That meant he needed to drop 7 volts across a series resistor. However, we were lacking the important information about current. He looked on the packaging of the diode and it provided the specific milliamps needed. That allowed me to determine the correct resistance to put in series with the LED. While we were still on the phone, he hooked up the circuit. Bingo! LED was on and nothing was burning. It felt good to know that my brain can still work through simple electronics when necessary.
Excellent explanation! I really enjoy learning from people who truly understand what they are teaching! Question: How do you figure out an LEDs values if you have no literature, like scavenging from used boards or replacing a bad LED etc.? Thank You
say you have a 5V power supply, connect a LED and a 200 Ohm resistor as done here, Use a multi-meter (20 VDC setting) and measure the voltage across the LED - that gives the Vf
Another way of thinking is that a diode will always stay at almost the same voltage, while the current will adapt according to the resistor. The more difficult question is, how much power can a scavenged diode take? Use 200ohm like suggested and see how long it takes for it to die .. it's a scavenged diode after all ;) Most 'normal' diodes will live "forever" with a 1k resistor, most even with a 100ohm resistor .. the high power diodes are the ones that are more sensitive.
And yet another way of looking at the problem is to consider that almost every LED ever made can take a current of 20mA and will have a forward voltage somewhere between 1V and 3.5V. So get a 12V supply and a 470 ohm 1/2 Watt resistor, hook them up with the LED and measure the voltage across the LED with a voltmeter. You can then calculate the current. If you only have a 5V supply, then use a 180 ohm 1/4 Watt resistor, although that will give more variability in the current depending on the type of LED. If the LED can't take 20mA, it's not going to be much use to you anyway.
Interesting video, thank you. Thinking about the parallel placement of the diodes, does that then mean you could take the circuit power supply back down to 5V? It would mean you only need 45 ohms resistance and 0.072w, so a 0.25W resistor would be suitable again, right?
If you place the diodes in parallel, then each one must have its own current limiting resistor. It's fine to use a 5V supply and a 100 ohm 1/4 Watt resistor with each LED.
Great and very useful video, a whole series of basic electronics, how too videos wouldn’t go amiss. Maybe you could do a step by step, build a synth tutorial. A CS-80 using modern components may seem ambitious, but don’t let that stop you, or something like an SY-1, a mono synth that someone could use multiple example’s of to make a poly synth.
OK, confusing point at 4:50. It looks like the second LED turns on before the power is connected! In fact the first LED is shining through the second LED. It probably _did not_ look like that to Markus's naked eye, but eyes are far better than cameras at handling a wide range of brightness. Incidentally, I'm surprised we didn't see the infra-red LED light up, because the classic way to tell if an IR LED is working is to look at it with a camera. I just tried a DSLR and a webcam - both can see a TV remote's IR LED.
What would the feasibility of just stepping down the supplied current to keep the 1/4w resistor? I mean if it is just drawing 3.2v in parallel, less to burn off?
What a great informative video for the novice in electronics that I am , you make it so understandable that helps me so much. but I have two questions for you and that is what if I have model railway coloured led light signal that has a 12V power supply and needs to reduce down to 3V led's , red, green and amber, that only light up one at a time, do you apply the first example and would it be better to use a half watt resistor than a quarter watt one ?
Beautiful job explaining how to determine resistive voltage drop requirements on how to drive a led. Great job on identifying units in the equations. I think the video could have been better if you explained the equations used to get wattage. Like P=VxI and the other equation variants.
Thanks man! I always thought the thick part within the LED was always the cathode, until I plugged a yellow LED the other day and went: Uhm... it doesn't work. Turns out I had to connect it "backwards" (the cathode was the thin part in this case). And checking the little cut in the package (thanks to your video) I have now confirmed that was the actual cathode! (I don't tend to rely on the length of the wires).
Content is king, why don’t you do a step by step build a synth series? A CS-80 using modern components may seem ambitious, but something like an SY-1 would be interesting. Then people could make multiple examples of that mono synth for a poly synth variant. Should give you around two years of content. And then you’d have loads of The Fuller Luv Philtre synths out there. You could also get sponsorship from some parts source outlet where people can get their parts from. A win, win.
I would say that everything is right with this video, except for two objections. An LED which is rated at 20mA, does not positively need to be run at 20mA. They look just fine with only 10mA flowing through them, unless you want to be able to see their state in full sunlight. It's a benefit of modern technology, that they can make LEDs so bright. And so, I have often put resistors which exceed the values you calculated here, knowing that this will cause less current to flow. Further, on rare occasions I've had to change the operating voltage of a circuit, which contained no analog sub-circuit except for the LED's. And in cases like that, it would also have been inconvenient to have to change the resistor on each LED. So, if a maximum supply voltage of 12V is to be tolerated, I can also just say over the cuff, that a 1kΩ resistor will be 'safe'. It's just that the LED will seem a bit dull / half-bright. Given the same, single blue LED as you did show, a 500Ω resistor will come close to producing 20mA, because 12V < 13.2V.
That was a typo. I actually was scanning the comments to see if anyone had noticed (and then promptly forgot... until I saw your comment). ALL previous examples (all examples except the last one) are series. The last example is parallel. Good catch though :)
Very good and informative video. I have a question, how can you work out the resistance value if you do not have a spec sheet on the LED? Do you set up a circuit and measure the voltage across the LED and also the amps running through the circuit?
Great video thank you This will save me change since I love to play with electronics and have little clue about the value of using LEDs. I pop them in my project and they went dead. Where can I buy that bread board... what's the name.
So... I hope you'll read this at some point. My question is, what are you usubg to power this stuff?I've never done anything like this before but recently got into model building again, and I want to light up my projects. Now, I understand how to choose the correct resistor (Thank you, btw) but how do I choose the actual power source? How do I decide to go with either batteries or something I plug into the wall? Also, are you aware of any sites that sells circuit boards or power sources ready to go? Thanks a bunch!
Very informative video, thank you! As an old geezer with a newfound fascination in this field, please forgive a simple question… Why are you referring to resistors in ohms and then in watts? (Resistance vs power) Also, how do you identify the ratings of resistors? I bought a bag of them and have no idea! Many thanks!
Howdy, Brother! What resistor should I use if I have a yellow 10mm LED Emitting Diode (1.8-2.2V) powered by two AA Batteries (on/off switch in the loop)? I'm not even sure if I asked the question properly 🤠. Thanks for any assistance.
19:28 Instead of requiring a thicker resistor with a higher power tolerance, is it also possible to use two .25 Watt resistors in series whose sum equals the required resistance?
Thank you so much! But how can I calculate the maximum power of a resistor? I have desoldered a lot of old circuits, but there are no inscriptions on them except of color stripes indicating resistance. Knowing the resistance, is it possible to somehow calculate the maximum power?
Not really. You have to either buy resistors with a particular rating and remember what they are, or learn by experience roughly how big a resistor is when it's rated for 1/8W, 1/4W, 1/2W, 1W, etc. The other option is to pass a known current through it and see how hot it gets. If it's too hot to touch, you've probably reached its maximum power rating! If it's any help, start by assuming it's at least 1/4W (unless it's really tiny) and test with a current that would give 1/4W using P = I*I*R.
Cool video, I have recently gotten into building/ modding guitar pedals and part of that entails adding LEDs...this definitely helps break down that process so I can understand it. Is there a breadboard you would recommend to get started with?
Hi Tommysea9000 I just have a few odd breadboards that I have had for many years but you can pick them up cheaply on amazon and they should be fine. best wishes
Thanks for uploading! So in the last example i could also have taken TWO 110 Ohm resistors and the wattage would be ok again? 2.) Two different LEDs ask for two different resistors in two parallel strings?
Where did you get the equipment you are using could you send me a link or direct me in the right direction to obtain the type of equipment you have please . Great job in explaining everything you are awesome!!
How did the second LED light up before you completed the circuit with the 100 ohm resistor? Generally, you shouldn't drive any component higher than its rated current.
LOL, I wondered that until I realised the first LED is shining _through_ the second LED. If Markus has realised how bad it would look on camera, he'd probably have put them further apart.
Awesome explanation sir! Very informative, and taught in a way that the layman can understand. Very new to this, so please forgive me, but in regards to the wattage of the resistor, is there a disadvantage of just using one with a high enough rating other than its size? Lets say your project only required 1/4 watt, would there be any disadvantages in using a 1 watt resistor?
Can you explain why my 3V 20 mA LED fail when using one type of 3V cell battery after 2-3 seconds and they don't after using another size/type 3V cell battery, like a 2450....Something to do with internal resistance of the battery??? In my example, I don't use any resistor....
I'll just point out that you should never wire LEDs in parallel with a single resistor. Even the same type, make and batch of LEDs will have variance and so one will conduct more brightly than the others, and thus be taking more of the current. This will inevitably lead to failure, which will then increase the current to the other LEDs (in the case of two LEDs, the remaining one will get double its rated current) and eventually all of them will fail - pretty spectacularly for the last one(s)! To be safe, every LED requires its own resistor to completely negate manufacturing tolerances.
Also he should have stated that the current rating of the LED is the maximum current spec before the LED fails. I usually go for half the rated current value. It will be bright enough.
Thanks for the video! Question please: would I be correct in assuming that 4 for these LEDs could be used in series without a resistor is using a 12 VDC power supply?
Hello I need help. I am installing an led switch on my guitar with current rating 5amps and 12v. I am connecting the switch to a 9v battery. What size resistor do I need?
Great video, Markus. 😃🙏🏼 I specially like the triangle. When I got familiar with that at school I used it at many formulas. 😉👍🏼 I only have one critic to say... Don't put the dot (comma) in the middle of the numbers! Then it can be mistaken for the multiplication sign and is very annoying. 🙈😉
Hi,I have a little problem where I converted my dash lights on my car to Blue LED's but the way I had to mount them meant one is further down the tube making it closer to the dash text so this one appears a bit brighter than the other one, could you suggest what resisters I could try to reduce this one to get them to match. They are 12 volt 5w T10 plug LED'S. Thanks.
Funny ... just a week ago I googled for a resistor in 24 V 5 A source and an LED for "power on". I choosed 1 kilo-ohm and it worked. But this here is a much better solution. Maybe that's why the almighty internet has offered me this video.
Brilliant video, now what about helping slot car guys with lights in the cars What value of resistor will be needed for a variable supply from say 3.2 volts upto 12 volts as this is generally the maximum voltage going to the car, understanding they want max benefit of the lighting, consider that fitting a lm7805 is just not practical and requires more soldering and securing, would they connect in series or parallel You valuable experience will be greatly appreciated
So question and you may have answered this already, on the last example. Could you divide the Amp load between two resistors to avoid burnout ? How would you calculate that ?
@Kenn Mossman right so if 1 resistor can't handle the current and it overheats and burns up would multiple resistors handling the current be the best practice to be able to handle the excess. I know I am probably not thinking rightly on this
This is THE BEST tutorial video of this subject! I hope you make more of these! The whiteboard, clearly drawn and written and spoken at a calm pace, the perfect combination! This setup works perfectly for teaching purpose!
Ohm's Law is pretty simple. You did a pretty good job of explaining it without dumbing it down too much.
Eureka!!! It has sunk in.... I wish I could have grasped this 10 years ago. What a great technique you have for teaching folk like me. Thank you.
I have struggled for years! trying to figure this stuff out. You single handedly demonstrated this better than anyone, and simple enough where I now understand it. I have been thunking my head over this so many times, but now I did it one last time because it was so easy to do and makes more sense than ever before. Thank you.
Its simple. Just check the voltage drop of the LED and calculate the resistor value for 10mA current. For indicators even 2 mA current is enough. Even you dont have to be exact, just find nearest value of resistor you calculated.
LOL!
This is like our first physics lesson in 7th grade. My grandpa taught me this when I was about 7 though beacause he was a physics teacher.
Sounds like you are missing the most basic of electronics skills.
You should have bought and read a basic electronics book for $10. Then you would have known in an hour or two and not years.
@@rimmersbryggeri You studied about diods and led in 7th grade?
You have done a superb job of explaining and illustrating the basics and managed to clear up a number of questions I had concerning led's and resistors and such. I've always been curious about basic electronics but never really pursued the topic in any real depth. I have done a bit of basic house wiring, but this stuff is new to me and looks like fun. The winters here are cold ... and longish. Thank you. I really appreciated your laying out each of the formulas.
This is the best explanation I've ever found on figuring out a resistor for an LED! Well explained!
I wish I had a teacher like you in school... you broke it down to bare basics... Great JOB!!!! thank you.
I would just like to say.....that was the most simple way of explaining the triangle....when I was at trade school doing my electrical apprenticeship...at the start the way this was explained was so SUPER CONFUSING MY HEAD WAS GOING TO EXPLODE...🤯
SO HATS OF TO YOU ON A SIMPLE WAY OF SHOWING A WAY THIS ALL WORKS....I WISH I COULD HAVE BEEN SHOWN THIS BACK IN THE DAY....WELL DONE...👍
Hey, youre so nice and teaching this as simple as possible and taking it slow... it ecourages me, a commoner, to study this. I always thought I would never get it, but now I actually do. Thank you Sir
Glad I can help. best wishes
You Sir have a gift to teach stuff with such clarity, plus you've covered the topic in its entirety leaving nothing out. Thank you !
Thank you very much for your kind comment.
I was struggling with this for 3 years... And now I understand everything... You're amazing bro keep your good work 😉
I really appreciate you making this video. I'm 70 and just now getting into messing around with LED's and breadboards etc. Much of the I R V triangle is still a bit of a puzzle to me and hopefully this old brain will eventually learn to correctly apply the appropriate formulas where needed. I have no idea how far I'll go with this stuff but it's pure fun for now. Thanks again.
Scott
Good for you, hmmm, um put your finger over the value you want, so if its V then IxR, if it is if you want Current (I) then it's V over R (V/r or V divided by R) because V is over R. Sorry didn't watch the vid maybe he/she says this. Then you have Watts so P Power (at the peak of the triangle) = I x V. Type in Ohm's Law to your browser then go to images and you should find a wheel image that uses more conventional maths. Stops my brain falling apart like a chocolate orange. You'll get the hang of it. :) Many electronics shops have them as a bookmark. Such as I=√P/R..... Hi from Oz.
Very good show for this 62 year old that’s adding some electronics related improvements to his model railway! You are an excellent instructor, and provide tons of information in an easy to comprehend way! Thanks! Subbed!
Thank you very much Tom. If I had more room I would love to build a model railway but there is not enough room to swing a cat where I live. Best wishes
@@markusfuller “Not enough room to swing a cat!” I love it! Ha!
Exactly the same reason as I am glad I learned this. Indicator lights for a display panel for my HO railway.
Hands down one of the best explanations I've ever seen... thank you brother! SMJ 23
Brilliant.
You've actually described this issue simply.
Now we understand.!🤔😊
Thank you.
This simple tutorial really helped me understand how to put some electronic components work together in a circuit adhering the best practices as in my case I am a visual learner.
More video like this please.
FINALLY! Someone explaining this clearly. Very much appreciated 🙌
Good video. Takes me back to my Signal Corps radio school days; we spent a lot of time calculating circuits using Ohms law. This was years before calculators were available- man, they make electronics SO much easier!
Ft Gordon?
You are the best Ohms law teacher ever❤
Thank you for this. I'm a novice amateur in electronics and had been wondering how to determine what size resistor to use. Your Examples make perfect sense to me.
Bought some 5050 SMD LED's for a project and this was valuable information. Never really got into RGB's that much so I'm learning from videos like this. Thanks for the info, you helped me more than you know.
What a fantastic video. I have been struggling with wondering if I had to add the total Vf for led's in parallel or series. I found your vid by accident and it has saved my sanity. Thank you for uploading it and you are a great teacher.
Every other tutorial spoke about avoiding burning up of LED but first time saw tutorial about how to avoid burning up of Resistor. very useful this
This took me back to my R.A.F. basic electronics training ... great refresher - thank you !!
Mate, you make this process much easier than other videos.
Thanks Sir!
Never have been in any electronics class in my life, you made this very easy. I can say, I just got my first crash course... Thank you sir...
I love messing around with electronics, yes did made some messes before, but am still here... 😂😂😂
Sir all the years in college, and you are the only one I understand.
Thank you for taking the time to make this video, extremely informative.
Nice video, Markus.
This is the first one of your videos I've ever seen, keep up the good work!
cant thank you enough ive asked and read but couldnt take it in you explain so well that ive finally got it thank you from all our beginners we will get there in the end with teachers as good as you are colinxxx
Vary good video. I learned more from your video on LED circuits then other videos I have watched. I was hoping to see more electronics videos but found they're mostly musical instruments.
I can’t thank you enough for the math lesson AND lab demonstration. Great Post!
Splendid, simple instruction. Much appreciated! If I have a higher voltage source, say 12v, will a larger resistor mitigate the potential burn out? Ah! You’re well ahead of me.
Yes. That's the purpose of the resistor. Just perform the calculation for 12v
Exactly what I was looking for. Graduated electronics tech course nearly 40 years ago and infrequently used the info. Knew what I was looking for to refresh my memory but couldn't find it till now. A near perfect presentation. Thank you. I recognized the Ohm's law triangle and knew where you were going with the power calculations so I could follow but would have liked to see the P - I - E triangle as well just to be sure I was remembering it all correctly. Also, I was a bit confused at 19 min 41 sec into the video I read "This example would be less efficient than the previous example of running the LEDs in parallel". Wasn't the previous example in series? Sincerely not busting your chops, I just need to be sure because I'm easily confused.
Hello. firstly thank you for your kind comment, I must rewatch the video and have a look at what I said at 19min41s . I made this video a while ago and cannot remember what I said but I have made mistakes before in other videos so I may be able to add some text on the video to correct any mistake or if not place it in the about section under the video. thanks for pointing this out to me. best wishes.
There is a typo on the screen. The LEDs are in parallel and each want to take 20mA , whereas the previous series example they were sharing the same 20mA.
LED (indeed all diodes) should not be connected in series like this a fraction of a mV difference is all that is needed for ALL the current to go through ONE LED and cause it to very quickly fail (sometimes dramatically). The better solution is to add a limiting resistor in series with each diode and break the relationship.
Use the series configuration if you have a lot of voltage and the parallel if you are running from a low voltage.
Efficiency of design is also understood by looking at the power wasted by the LED, you obviously want that to be as small as possible
@@deansmith4752 You mean "all diodes should not be connected in _parallel_ like this ..." and that's because whichever diode is taking more current, it will heat up more and its negative temperature coefficient will cause it to draw more of the current, and so on. The power consumed by the LED is fixed for a given brightness, so the efficiency is governed by the power wasted in the dropping resistor (not the LED). To maximise efficiency, you want the supply voltage not too far above the on-voltage of the LED, but that makes the dropping resistor small and can lead to greater variations in current consumed for changes in temperature or variations in samples of the LED.
@@RexxSchneider I'd say you're both right. To summarize it; a series connection *guarantees* that the same amount of current (A) runs through each LED. A parallel connection of LED's *guarantees* that the same voltage potential is applied across them.
LED's are inherently a bit "tricky" in ohm's law, as they don't follow a linear relationship between voltage and current since it's an "active component", being a semiconductor. Since ohm's law doesn't really work on active circuits, we have to use static/idealized values for semiconductors. LEDs, and regular diodes for that matter, are simple enough since when surpassing their forward voltage, (or reverse breakdown voltage), they'll be idealized as essentially having resistance that IS the proportional of voltage and current, and likewise, when below the threshold, we could in a way say the resistance is infinity. But naturally a LED that's ON will heat up, and that's the culprit that makes LEDs so "hard to calculate" with Ohm's law, cause that changes it's forward voltage. The hotter it gets, the lower the forward voltage gets.
So dean is correct in that when LEDs are in series, one single LED with different forward voltage would drop less voltage, allowing more current to pass in total, and also leaving more potential for the next LED. It should be noted that the next LED would then sink more total power, decreasing it's forward voltage faster than the first, and kinda "balancing" it out. The solution proposed isn't in effect changing this fact, but does make it look a lot easier to calculate individual LED in a diagram. I think what Dean meant by "current to go through ONE LED" was that one led would drop all the voltage, in effect "consuming all the current", since the current would be the same across all LED's in series what. (disregarding inductance etc.)
Rexx is absolutely correct that LEDs shouldn't be connected in parallel, but the "like this" doesn't show in the video, since they all have a limiting resistor. But if the LEDs were indeed in parallel, this is when Dean's comment would happen. One LED would be a fraction out (inevitable) of the forward voltage of the others, thereby making it drop less voltage and in turn let more current flow. This is thermal-runaway waiting to happen, as that LED would consume more power, getting hotter, dropping even less voltage but passing even more current. I wouldn't say that "the power consumed is fixed for a given brightness", since brightness tends to get weaker when over-driven (more power used for heat than for producing photons). But I get the idea.
The reason a parallel circuit could be stable a while with very similar LEDs, is that power consumption is equal to voltage times current. A LED is dropping less and less voltage, but taking more and more of the current, making it effectively use close to the same amount of power. But when it drops enough voltage to drag another LED into it's forward voltage threshold, that other LED is drastically affecting the total current in the circuit, since it's basically "turning off" letting all it's current flow through the other LEDs. This is when they'll get over driven and blow. (sometimes dramatically) ^^
So to summarize: use a LED driver to maximize efficiency. It changes voltage in accordance with current drawn, thereby limiting the total current and not exceeding the rating of any LEDs, and use a resistor as a "current limiter" that would account for a certain drop in forward voltage. It's easier, but simplicity has it's tradeoffs.
Wow, sorry for the wall of text... I got on a roll there..
@@arsenic1987 You have a decent grasp of what is happening when diodes are connected in parallel, but underestimate the effect of the exponential relationship between voltage and current. When you say, for example, _"A LED is dropping less and less voltage, but taking more and more of the current, making it effectively use close to the same amount of power"_ you miss the point that a forward voltage increase only needs be around 20mV to produce a doubling of the current through it. That's equivalent to as little as 10°C rise in temperature. That means that the power consumed by the diode (or LED) does increase quite dramatically as its temperature increases; the increase in current is is far greater than the minute change in forward voltage. It definitely does not _"effectively use close to the same amount of power"._
The whole point of the dropper resistor is to stabilise the current against changes in temperature since an increase in current as the diode heats up will cause more voltage to be dropped across the resistor, thus reducing the voltage across the diode and significantly reducing the increase in current because of the exponential relationship.
First of all english is not my mother language, even that i've fully understood ! Why you was not my teacher 60 years ago?! Thank so much for this clear and fully understandable explanation. Regards from burgundy. ..
You, Sir, are a great teacher! You made this very easy to understand and apply. Thank you!
Great tutorial. I had no idea about ohms and resistors. I have learned so much from your video. Thanks.
`You are a good teacher..... Know how to explain things in a very simple way.
Such a great lecture, so informative and professional thank you kindly!!!
2:19 - We learned the formula as U = R * I. I've never heard of voltage referred to as E. Unless talking about the underlaying electric field vector, but in that case (even though analogous to voltage potential), the whole formula is replaced with "Electric field vector = amperes pr unit area * resistivity in ohm-meters"..
Apparently, the U is used only because the names of quantities should not be the same as the unit name itself. (Ampere = unit, I = amount of Amperes(A). Ohm(Ω) = unit, R = amount of ohms(Ω), V = unit, U = amount of Volts).
So it's just a note for English speaking countries. (U = RI) is the equivalent of (V = IR). U or V = tension or potential. I = flow or intensity, and R = resistance. Respectively measured in units of Volt, Ampere, and Ohm(Ω).
Oh, and since using power as well, could have drawn the corresponding "power triangle". P = V * I (Or P=U*I). Where P is power, measured in Watt (w).
Thank you so much for that very clear explanations. I’ve been searching for that for a long time.
Very well explained. I truly left with some very interesting and new information. Great job!
Thank you for producing this educational video.
Very fine basic video indeed! Thank you, Markus. Good even for an old hand at this art.
By far, the best hands on demo for this ever. THANK YOU SIR.
Very nicely explained and good making of Video. Thank you sir. I am a novice in this area and I loved the way you explained the entire things.
So glad I found this guy, he speaks good English 😂❤
At 9:09 Different LEDs in series work well. At 13:00 You need seperate resistors if they are in parallel.
Thank you, you've explained everything that I needed to know for a small project I'm working on.
Thank you for a very interesting video and the careful way in which you told us what has been puzzling me whilst experimenting with LEDs. Can you please say if it is possible and how to calculate the requirements of an LED that has not got a data sheet?
Many thanks Benters
I went through an Air Force tech school back in 1976. I understand everything you explained. Well done. But, I've gotten a little rusty over the years. One day I got a phone call from my son who worked at Circuit City as an installer of various electronics. He had a question which made me re-think a simple series circuit. He had an LED that runs on 5 volts that he needed to install into the 12 volt car. That meant he needed to drop 7 volts across a series resistor. However, we were lacking the important information about current. He looked on the packaging of the diode and it provided the specific milliamps needed. That allowed me to determine the correct resistance to put in series with the LED. While we were still on the phone, he hooked up the circuit. Bingo! LED was on and nothing was burning. It felt good to know that my brain can still work through simple electronics when necessary.
Excellent explanation! I really enjoy learning from people who truly understand what they are teaching!
Question: How do you figure out an LEDs values if you have no literature, like scavenging from used boards or replacing a bad LED etc.?
Thank You
say you have a 5V power supply, connect a LED and a 200 Ohm resistor as done here, Use a multi-meter (20 VDC setting) and measure the voltage across the LED - that gives the Vf
Another way of thinking is that a diode will always stay at almost the same voltage, while the current will adapt according to the resistor. The more difficult question is, how much power can a scavenged diode take? Use 200ohm like suggested and see how long it takes for it to die .. it's a scavenged diode after all ;) Most 'normal' diodes will live "forever" with a 1k resistor, most even with a 100ohm resistor .. the high power diodes are the ones that are more sensitive.
And yet another way of looking at the problem is to consider that almost every LED ever made can take a current of 20mA and will have a forward voltage somewhere between 1V and 3.5V. So get a 12V supply and a 470 ohm 1/2 Watt resistor, hook them up with the LED and measure the voltage across the LED with a voltmeter. You can then calculate the current. If you only have a 5V supply, then use a 180 ohm 1/4 Watt resistor, although that will give more variability in the current depending on the type of LED.
If the LED can't take 20mA, it's not going to be much use to you anyway.
Perfectly explained!!!
Interesting video, thank you. Thinking about the parallel placement of the diodes, does that then mean you could take the circuit power supply back down to 5V? It would mean you only need 45 ohms resistance and 0.072w, so a 0.25W resistor would be suitable again, right?
If you place the diodes in parallel, then each one must have its own current limiting resistor. It's fine to use a 5V supply and a 100 ohm 1/4 Watt resistor with each LED.
pretty simple right? You explain it very clearly, I now get it in one video. My project can roll now!
Great and very useful video, a whole series of basic electronics, how too videos wouldn’t go amiss. Maybe you could do a step by step, build a synth tutorial. A CS-80 using modern components may seem ambitious, but don’t let that stop you, or something like an SY-1, a mono synth that someone could use multiple example’s of to make a poly synth.
OK, confusing point at 4:50. It looks like the second LED turns on before the power is connected!
In fact the first LED is shining through the second LED.
It probably _did not_ look like that to Markus's naked eye, but eyes are far better than cameras at handling a wide range of brightness.
Incidentally, I'm surprised we didn't see the infra-red LED light up, because the classic way to tell if an IR LED is working is to look at it with a camera. I just tried a DSLR and a webcam - both can see a TV remote's IR LED.
Nicely explained. Can you please tell be about that circuit board tester you're using & possibly where it can be purchased. Thank You.
What would the feasibility of just stepping down the supplied current to keep the 1/4w resistor? I mean if it is just drawing 3.2v in parallel, less to burn off?
What a great informative video for the novice in electronics that I am , you make it so understandable that helps me so much. but I have two questions for you and that is what if I have model railway coloured led light signal that has a 12V power supply and needs to reduce down to 3V led's , red, green and amber, that only light up one at a time, do you apply the first example and would it be better to use a half watt resistor than a quarter watt one ?
Beautiful job explaining how to determine resistive voltage drop requirements on how to drive a led. Great job on identifying units in the equations. I think the video could have been better if you explained the equations used to get wattage. Like P=VxI and the other equation variants.
Thank you. This is the most wanted basically calculation.
Thanks man! I always thought the thick part within the LED was always the cathode, until I plugged a yellow LED the other day and went: Uhm... it doesn't work. Turns out I had to connect it "backwards" (the cathode was the thin part in this case). And checking the little cut in the package (thanks to your video) I have now confirmed that was the actual cathode! (I don't tend to rely on the length of the wires).
That was sooo easy to understand, thank you sir!!
Thank you ! Crystal clear and simple even for a lazy brain like me 🙂
Content is king, why don’t you do a step by step build a synth series? A CS-80 using modern components may seem ambitious, but something like an SY-1 would be interesting. Then people could make multiple examples of that mono synth for a poly synth variant. Should give you around two years of content. And then you’d have loads of The Fuller Luv Philtre synths out there. You could also get sponsorship from some parts source outlet where people can get their parts from. A win, win.
Man this is best video I've seen for ohms. Where you 25 years when I was at school!?!?!
I would say that everything is right with this video, except for two objections. An LED which is rated at 20mA, does not positively need to be run at 20mA. They look just fine with only 10mA flowing through them, unless you want to be able to see their state in full sunlight. It's a benefit of modern technology, that they can make LEDs so bright. And so, I have often put resistors which exceed the values you calculated here, knowing that this will cause less current to flow. Further, on rare occasions I've had to change the operating voltage of a circuit, which contained no analog sub-circuit except for the LED's. And in cases like that, it would also have been inconvenient to have to change the resistor on each LED. So, if a maximum supply voltage of 12V is to be tolerated, I can also just say over the cuff, that a 1kΩ resistor will be 'safe'. It's just that the LED will seem a bit dull / half-bright. Given the same, single blue LED as you did show, a 500Ω resistor will come close to producing 20mA, because 12V < 13.2V.
19:45 the previous explain was of running the LEDs in parallel?
I'm sorry, I get confused very easily & I still don't know what to think.
That was a typo. I actually was scanning the comments to see if anyone had noticed (and then promptly forgot... until I saw your comment). ALL previous examples (all examples except the last one) are series.
The last example is parallel. Good catch though :)
Very good and informative video.
I have a question, how can you work out the resistance value if you do not have a spec sheet on the LED?
Do you set up a circuit and measure the voltage across the LED and also the amps running through the circuit?
Do you set up a circuit and measure the voltage across the LED - yes
Great video thank you
This will save me change since I love to play with electronics and have little clue about the value of using LEDs. I pop them in my project and they went dead. Where can I buy that bread board... what's the name.
Really great video! What if you have loose leds, is there a way to work out what voltage and current it requires?
I just use a variable power supply or variable resistor when theres lots of unknown leds to work out.
Hi Mark, you should now continue this article for running a LED on ac with higher voltage as well, with and without a rectifier!
So... I hope you'll read this at some point. My question is, what are you usubg to power this stuff?I've never done anything like this before but recently got into model building again, and I want to light up my projects.
Now, I understand how to choose the correct resistor (Thank you, btw) but how do I choose the actual power source? How do I decide to go with either batteries or something I plug into the wall?
Also, are you aware of any sites that sells circuit boards or power sources ready to go?
Thanks a bunch!
Very informative video, thank you! As an old geezer with a newfound fascination in this field, please forgive a simple question…
Why are you referring to resistors in ohms and then in watts? (Resistance vs power)
Also, how do you identify the ratings of resistors?
I bought a bag of them and have no idea!
Many thanks!
Google resistor bands
Howdy, Brother! What resistor should I use if I have a yellow 10mm LED Emitting Diode (1.8-2.2V) powered by two AA Batteries (on/off switch in the loop)? I'm not even sure if I asked the question properly 🤠. Thanks for any assistance.
19:28 Instead of requiring a thicker resistor with a higher power tolerance, is it also possible to use two .25 Watt resistors in series whose sum equals the required resistance?
yes
Thank you so much! But how can I calculate the maximum power of a resistor? I have desoldered a lot of old circuits, but there are no inscriptions on them except of color stripes indicating resistance. Knowing the resistance, is it possible to somehow calculate the maximum power?
Not really. You have to either buy resistors with a particular rating and remember what they are, or learn by experience roughly how big a resistor is when it's rated for 1/8W, 1/4W, 1/2W, 1W, etc. The other option is to pass a known current through it and see how hot it gets. If it's too hot to touch, you've probably reached its maximum power rating!
If it's any help, start by assuming it's at least 1/4W (unless it's really tiny) and test with a current that would give 1/4W using P = I*I*R.
Cool video, I have recently gotten into building/ modding guitar pedals and part of that entails adding LEDs...this definitely helps break down that process so I can understand it. Is there a breadboard you would recommend to get started with?
Hi Tommysea9000 I just have a few odd breadboards that I have had for many years but you can pick them up cheaply on amazon and they should be fine. best wishes
Thanks for uploading!
So in the last example i could also have taken TWO 110 Ohm resistors and the wattage would be ok again?
2.) Two different LEDs ask for two different resistors in two parallel strings?
yes two or more resistors, usually the same value and wattage can be used in series or parallel to 'increase' the wattage
Two different LEDs ask for two different resistors...........................why? too vague a question
Very good explanation. Thanks
Very nicely explained.
Bless you!
Thank you
Nice work. What model breadboard is that at 13:25 in the video? I like the layout of it.
Where did you get the equipment you are using could you send me a link or direct me in the right direction to obtain the type of equipment you have please .
Great job in explaining everything you are awesome!!
How did the second LED light up before you completed the circuit with the 100 ohm resistor? Generally, you shouldn't drive any component higher than its rated current.
LOL, I wondered that until I realised the first LED is shining _through_ the second LED. If Markus has realised how bad it would look on camera, he'd probably have put them further apart.
Awesome explanation sir! Very informative, and taught in a way that the layman can understand.
Very new to this, so please forgive me, but in regards to the wattage of the resistor, is there a disadvantage of just using one with a high enough rating other than its size?
Lets say your project only required 1/4 watt, would there be any disadvantages in using a 1 watt resistor?
No, apart from size and cost.
You are a good teacher.. great job keep it up!
Mark where did you purchase your breadboards with the power connectors? 🙏🙏
I’ve searched everywhere and can’t find anything.
Can you explain why my 3V 20 mA LED fail when using one type of 3V cell battery after 2-3 seconds and they don't after using another size/type 3V cell battery, like a 2450....Something to do with internal resistance of the battery??? In my example, I don't use any resistor....
yes.....internal resistance of the battery varies
for parallel what happens when you put resistors just in front of each led, can they be treated as singular and not have to add the ohms?
Though, you put the second led, already it lights, how can that be without a resistor closing the circuit?
ikr, wtf? I wondered about that too...
I'll just point out that you should never wire LEDs in parallel with a single resistor. Even the same type, make and batch of LEDs will have variance and so one will conduct more brightly than the others, and thus be taking more of the current. This will inevitably lead to failure, which will then increase the current to the other LEDs (in the case of two LEDs, the remaining one will get double its rated current) and eventually all of them will fail - pretty spectacularly for the last one(s)! To be safe, every LED requires its own resistor to completely negate manufacturing tolerances.
Also he should have stated that the current rating of the LED is the maximum current spec before the LED fails. I usually go for half the rated current value.
It will be bright enough.
Or a topology compromise somewhere between the two cited extremes
Thanks for the video! Question please: would I be correct in assuming that 4 for these LEDs could be used in series without a resistor is using a 12 VDC power supply?
no
Hello I need help. I am installing an led switch on my guitar with current rating 5amps and 12v. I am connecting the switch to a 9v battery. What size resistor do I need?
Great video, Markus. 😃🙏🏼
I specially like the triangle. When I got familiar with that at school I used it at many formulas. 😉👍🏼
I only have one critic to say...
Don't put the dot (comma) in the middle of the numbers! Then it can be mistaken for the multiplication sign and is very annoying. 🙈😉
Hi,I have a little problem where I converted my dash lights on my car to Blue LED's but the way I had to mount them meant one is further down the tube making it closer to the dash text so this one appears a bit brighter than the other one, could you suggest what resisters I could try to reduce this one to get them to match. They are 12 volt 5w T10 plug LED'S. Thanks.
Funny ... just a week ago I googled for a resistor in 24 V 5 A source and an LED for "power on". I choosed 1 kilo-ohm and it worked. But this here is a much better solution. Maybe that's why the almighty internet has offered me this video.
Great video Mark, thank you👍
Brilliant video, now what about helping slot car guys with lights in the cars
What value of resistor will be needed for a variable supply from say 3.2 volts upto 12 volts as this is generally the maximum voltage going to the car, understanding they want max benefit of the lighting, consider that fitting a lm7805 is just not practical and requires more soldering and securing, would they connect in series or parallel
You valuable experience will be greatly appreciated
So question and you may have answered this already, on the last example. Could you divide the Amp load between two resistors to avoid burnout ? How would you calculate that ?
resistor burn-out?
@Kenn Mossman right so if 1 resistor can't handle the current and it overheats and burns up would multiple resistors handling the current be the best practice to be able to handle the excess. I know I am probably not thinking rightly on this
@@jeremyk.1689 one solution would be use 2 or more resistors - either in parallel or series. If in parallel then of the same value and wattage
@@kennmossman8701 Gotcha, thats what I thought. thanks for the help.