How to Turn an LED On 

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As soon as he mentioned using a capacitor instead of a resistor, I knew there was going to be an explosion.

Damn, when Mehdi is worried about his circuit's safety, you know it's serious shit

Hi All! Around 6:40, although my first LED was dead from the first capacitor experiment, the second LED was not dead! As some of you pointed out, I totally forgot about the fact that the LED, forcing the current one way through the capacitor only, charges the capacitor to the main voltage peak (hence the one quick blink) and after that because the capacitor is charged, the voltage across the LED doesn't go positive and so it won't turn on any more. The solution would be to discharge the capacitor, say by placing a reverse diode across the LED to discharge the capacitor in the negative cycle. The reverse diode could also be an LED, which means in both cycles you would have an LED on causing less flicker, which is nice!

I like Mehdi's style here. He demonstrates even with a university education and experience under his belt, an engineer still must build the circuit in real-life and see what happens.

Given enough current, pretty much _every_ component is light emitting.

I'm so happy to have learned about the relationship between event horizons and LEDs. Now I will be able to say "I already know all about LEDs, come on..." in the next video!

I think this is one of my favourite videos. I could not stop laughing every time Mehdi changed up the whiteboard overlay. First he was in front, then his head was overlayed, then he was behind the whiteboard, then he was in front and tiny. So good. Mehdi has such a great eye for comedy. Like the latity song. Gold Jerry, Gold.

Real footage of gargamel doing magic

Hey Electroboom. Could you do a video on what transistor is a good pick for various applications? (driving a motor, logic level shifting, HF radio, UHF radio, sound amplification, signal filtering, etc)? There are SO MANY different transistor technologies out there, and I don't know what to pick for which application!

Thanks to you, Mehdi, I have finally reached a level where I can predict most of your BOOMs instead of being surprised by them. Thanks for all the teaching and entertainment that carries me through university!

Chuck Norris once hired an electrician and taught him how to survive being shocked thousands of times.

This video is great. The fact that it goes through theoretically "correct" ways to drive an LED, and the reasons for why there are better ways, which follows the learning curve so well. Bravo

when you turn on an LED is pretty normal , but when the LED turns on you .... thats a different story.

00:32 Event Horizon is a great sci-fi horror movie with Sam Neill, and its relation to LEDs is that it's too scary to watch without the lights on.

14:57 He's invented the most stressful lightbulb ever

I remember studing this stuff for my Amateur Extra Radio exam. Amazing how much I retained, but still love seeing your practical demonstrations. Thank you for posting these.

5:46 America be like: don't mind if i do

1:42, oh man I enjoyed it so, much (yelling in pain) sorry 🤣🤣🤣🤣😂😂

4:30 Use that LED diode to make a backlight for an LCD display!

At 5:13... a light emitting resistor!

7:02 That‘s something we don’t hear Mehdi say very often! :D :D

ElectroBoom videos have more effective jumpscares than you regular horror film

Love you dude! I was graduated as Electronic technician some 30 years ago. And it's nice that most of my knowledge is still valid today. Than I started an Electrical Engineering university course, but I feel in temptation with Computer Sciences, and I didn't mess up much with electronics all this time. You bring so much fun memories. Thank you very much for your work. 😂

You really baited me to watch the entire video with that event horizon. Well played.

10:14 You acually just described half a semesters worth of Electronics I (EE Major) in like 20 seconds, I wish this was there when I struggled with the class LOL

5:18 ... lmao 🤣

I honestly did not expect a video called "How to Turn an LED On" to finish up by actually teaching us how to make a full-on switching power supply (including the principles involved). That was really impressive (and cool).

0:27 You already gave an answer, whatever is in the event horizon or the LED, it can't go back

Now that we have had LEDs taught Mehdi style, it would be cool to see a zener diode video. It would be funny to see you illustrate an over voltage protection system using a zener diode after you have already destroyed a bunch of LEDs.

Instructions unclear, accidentally caused a massive black out in my local town because I accidentally blew the entire local power station itself

For a simple LED its just a DC source like an I/O port, the LED, and a resistor. But in commercial designs, driving an LED efficiently as well as controlling the brightness actually takes a bit of work. There are two methods. The most common method is to use a current-controlled driver chip, usually set to near the LED's rated current (e.g. 20mA), and you then control the brightness with a PWM. The PWM is sometimes built-into the driver chip and controlled via I2C, but it is just as easy to use a little PIC microcontroller to handle the PWM. The PWM typically runs at 40KHz and has 256 brightness levels (base clock is thus around 10MHz). LED driver chips allow you to set a fixed current with a resistor and you use something like a PIC microcontroller to control it. However, there is a 'minimum' brightness when using this method because LED driver chips can't actually turn on and off quickly enough to handle PWM settings below around 100uS. The driver chips work best for LED strings. We don't use inductors... Actually, we try to avoid using inductors at all because they vibrate and they are expensive components compared to other components on the board. They are EXTREMELY efficient. We try to arrange the voltage drop across the string such that the voltage is close to zero at the bottom of the string. The driver chip then basically connects the bottom to ground (current controlled), so the losses through the driver chip are extremely low. e.g. if you have a 20V series string of LEDs you make your power supply something like 21V and thus the driver chip's internal FETs only has to dissipate 1V, yielding an efficiency of 95%. The second method is to servo the current with a FET/op-amp circuit for brightness and use a simple fixed PWM to limit power consumption. Again at around 40KHz. This is more difficult to get right because the FETs linear range is really sensitive to voltage (hence why it has to be a servo), but it works. It isn't as efficient because the FET eats the difference, but it allows the PWM to have a wide pulse width without being too bright, which is important for certain transmitter/detector applications. Then finally, one might ask why use a 40Khz PWM instead of, say, 60Hz from a half bridge? Well... because the human eye can easily see the flicker at 60Hz, but won't see any flickering at 40KHz.

i love how you teach people by showing them what would happen if they make a mistake someone would actually make

First time catching a new upload after discovering your videos. I really appreciate your channel, and your incredible teaching. I ordered a Tesla coil kit yesterday (:

I was hoping that part at 9:18 would go on for like 5 minutes. :)

i was hoping for a dad joke of driving around in a car with an led in the back seat

I strongly believe that this man is immune to electricity, he just flinch because it's a primal instinct

I wish I was as funny as ElectroBoom. His combination of entertainment and learning together is genius. Love the videos.

"How many engineers does it take to light an LED?"

I never learnt so much in my 4 year bachelor's, as i do from your videos. I wish all teachers were like you :)

I love Medhi's unique way of getting me to watch his videos - asking me a question, then berating be for not knowing something else and telling me to listen. Thing is, it works, so you know I really can't fault him.

15:05 Holy shit how many times that shit when the probes and all the cables drag the whole montage down the table happened to me during laboratories? God dammit I felt that one...

Me:oh nothing blows up Also electroboom: 6:19

7:33 That was the most spectacular LED death.

On the topic of waveforms, rectified sine waves have to be one of my favorites. When using them in a music context, they can be really neat sounding....though doing them with an actual hardware analog synth is pretty much impossible

5:48 Ahh I see Mehdi is aware of US foreign policy. xD

5:19 That face after burning the resistor🙂

This episode was excellent from start to finish. The script, the effects, all of it made me chuckle. And yes, please discharge your capacitors when you're done with them. 💀⚡

3:43 -Medhi 2022 : "its on yeaayyyyy, is this what you want your life to be? an unintresting boring s-fwanawh"

5:25 In India, LED chains are available in local market where near about 80 LEDs are connected in series with some resistor (in series) also. Those chains are used for decoration and need to connect to 220v AC pwer outlet. After watching this video, I have decided not to use those chains anymore for their amount of power loss...

Never knew about that simple boost circuit for LED driving, high voltage spikes like that sketch me out. Always used a buck converter that has a sense resistor shunt for current control as opposed to voltage control. Always fun to learn new topologies. Great video as always.

at 1:35 I started to feel that something wrong will happen

Im literally learning about this in school in my electronics class! love your content, keep it up.

You make learning so fun. Thank you.

12:21 the intrusive thoughts winning

At this point, I instinctively flinch and squint whenever Mehdi plugs something in.

Hey Mehdi! Could you tell us more about transistors and in particular the difference between using them as amplifier vs. using them as switch?

14:50 if Mehdi is nervous, it's time to head for the bunker.

Thanks for the great educational and equally entertaining content. I legit look forward to watch your videos!

It is so much fun watching you! Absolutely loved it, I wish I did this at uni! ❤

5:19 The face of: "Yes, I had a very nice Italian vacation!" Hope it was good, seriously

5:55... In games i do

I love your "retroactive precision" edits to fix the script flubs :P

Excellent presentation! I almost spit coffee when I saw the scorched project board. It is so ElectroBOOM!

13:19 Finally, the one you've all been waiting for!

His messups always look genuine but I wonder what percentage of his "accidents" are not scripted. I imagine most of them are. He is not only a great electron manipulator but also an amazing actor!

In a future episode it would be cool to see the interactions between dimmer switches and led lights, how dimmer switches work, and why only certain LEDs are dimmable.

3:41 Power supply casually pumps out 10 amps short circuit like a champ

youre my new engineer teacher. i love your teaching style.

I love how he green screened himself over himself

At 12:02 One can add a small capacitor across the diodes to absorb a significant amount of the voltage spikes where it will discharge through LEDs over time untill the next inductor voltage spike. it's just takes the edge off the peek of the voltage spike across the diodes, and being small doesn't contribute much to lighting the diodes.

Thanks for always making me smile while learning ☺️❤️

Love your work. You got me with the bait and switch about the event horizon!

As a mechanical engineer with a little bit of knowledge of electronics. I forgot what I knew after watching this video😂😂

4:50 wow I learned something cool! Unfortunately I might forget it lol

This is now the FULL BRIDGE RECTIFIER CHANNEL

you know your getting old when your unibrow starts becoming a normal eyebrow, "luckly Keeps can prevent hair loss from happening in the first place. The earlier you take action, the more hair you’ll keep, Keeps the no.1 hair loss treatment for men"

I tried to build an LED driver once. I was pretty sure it was going to end up exploding because I understood it a lot less than Mehdi and he manages to blow everything up when he does know what he's doing

5:30 I belive he makes mistakes in every video so that he can rectify with funny accents

I wanna thank you, I am learning to become Car Electrician and your videos are helping me understand electrical part of the job

This one is a masterpiece! In school we just learned the resistor way. But of course there are more (power) efficient way. Thanks!

Did you know that you can also turn on a diode ? With 50A the usual become pretty bright for a brief moment

8:13 #toastBoard

Im subscribed to you when you had 700k subscribers and I’ve watched all your videos I literally love your explanations

Thanks, I needed this one.

Really cool are LED Drivers like the IS31FL3731. This can be controlled via I2C to handle a big array of LEDs. Most likely in your RGB keyboard one or more of these is installed.

Hey Mehdi, can you pleeeease consider an explainer on the different methods of dimming (TRIAC, 0-10v, Electronic Low-Voltage, Magnetic Low-Voltage, Incandescent/Halogen, etc.) and how they work?

Thanks for the share and the work !

You took something I already knew a bunch about and educated me even more. Awesome.

.14:05 I throwed my phone

6:20 I love how the bleep has reverb as if he doesn't actually swear he just makes bleep sounds

Electroboom videos has so much meme potential.

I understand all the technical words while watching along! Learning with a smile :)

This video was incredibly interesting and useful, thank you Mehdi !

Great video, but probably the best part of this one was the Sudden Accent Failure lol. Seriously though, some great infromation in this video. A lot of people don't think of driving LED's properly (including a lot of LED bulb manufacturers)

Another great vid dear Mehdi!! Thank you & God bless You!!

[EDIT] Wrong, check comments 4:45 no it's not. It's Vrms/2 or Vpeak/2✓2 7:35 it's not working because the current going through the capacitor is half wave rectified, not true AC. You would need two LED strings with reverse polarity to make that work.

While your use of a resistor in series with the AC line did light the LED, I expected it to fail because of reverse voltage exceeding the spec.

Very great information. Thanks much

Great video! That flash capacitor brings back memories, I’ve ‘discharged’ one where it welded itself to a screwdriver, and another time where it blistered my fingertip! Don’t touch them, they hurt more than a soldering iron.