Do all the things like ++ or -- rants, post your own rants, comment on others' rants and build your customized dev avatarSign Up
Get a devDuck
Rubber duck debugging has never been so cute! Get your favorite coding language devDuckBuy Now
Search - "pwm"
Being a student this was how my colleagues felt about my code and SQL procedures. They didn’t even let me create a change ticket to present to CAB 😂12
I've just disassembled this LED floodlight that I bought a while ago. It's some stupid little cheapie from a dollar store, so I figured that there'd be shit inside. But I wanted that LED cob.. a power LED :3
Well, shit wasn't too far off from the truth. The component choice is reasonable, but the design of the bloody thing.. batshit insane. The LED floodlight is powered by 4 AAA batteries, connected in series. So 6VDC. That then goes into this little tactile pushbutton, into the LED cob and then a 4.7 ohm resistor.
Well that's a pretty easy circuit.. let's remove the batteries and the casement, and put it on the lab bench power supply. Probes connected to the circuit with only the resistor and the LED cob in between (I didn't want to deal with the switch). Power supply set to 6V, current limiting to 500mA, contact!! And it works, amazing! So I let it run for a while to see that nothing gets too hot.. hah. After a minute or so, smoke would come out.. LED cob was a bit warm to the touch but nothing too bad. But the resistor.. I could cook water on it if I wanted to! 100 fucking °C, and rising. What the F yo?!
So I figured that I didn't want to put the resistor in between there. Just the LED cob now, which apparently has a forward voltage somewhere between 3.2V and 3.3V depending on how I set the current (500mA and 600mA respectively). Needed a bigger heatsink though, so I jammed one of my aluminium heatsinks on there. And it worked great! Very bright too, as it takes between 1.6 and 2W of power. Just for a comparison, the lighting in my living room is 4x5W and the ones on top of my dining table are 2x3W (along with some TL bar that my landlord put there.. fluorescent I think). So yeah, 2W is quite a lot for an LED, especially when it's all concentrated into one tiny spot.
That said, back to the original design with the resistor. 2 questions I have for that moron that designed this crap. First, why use a resistor for a power LED?! They needlessly waste power, and aren't good choices for anything that consumes more than 100mA. You should use PWM for these purposes, or tune your voltage on the supply side. Second, why go with 6V when your forward voltage is 3.3 at most? Wouldn't it make more sense to use 3 batteries with 4.5V? Ah, but I know the answer to the second one. AAA cells aren't rated for high loads like this. So that's likely why the alkaline cells that I had in there before have started leaking. Thanks, certified piece of shit!
Honestly, consumer electronics are such a joke... At least there's some components that I can salvage from this crap. Mainly the LED cob, but also the resistor and the tactile pushbutton perhaps.
One last remark that I'd like to make. This floodlight was cheap garbage. But considering that you can't do it well at that price, you just shouldn't do it. You know why? Because consumers always go for the cheapest. Makes a lot of money to build at rock bottom prices and make shit, but it damages the whole industry, since now the good designs will go out of business. That's why consumer electronics is so full of crap nowadays. Some unethical profiteering gluttons saw money, and they replaced the whole assortment with nothing but garbage. I'm sure that there's a special place in hell for that kind of people.17
I am in love.
I am in love with all the guys and girls working at Microchip support.
I am the kind of user that does not really understand what he's doing/what he wants to do, so I am constantly stuck in stupid configuration errors or looking for impossible solutions, yes I am THAT kind of a user...
Here is a PWM working, a support guy spent some minutes telling me that I have to connect to the right pin.
Ok, he had to tell me twice.😳
Thank you, it may have taken me days to find out this.
They does not know, but there is a HUGE amount of decreasing dumb question incoming 😈
Please be kind with me, and don't get mad when things will get serious, I will probably bring hell in your office, I am very sorry for that...
Still, thank you for helping the dumbest learner-by-mistake that doesn't know how to recognize a mistake.
I can't write this in the ticket system, I hope someone of you use devRant! (atsame54 office, I am talking with you!)
You are my stack overflow, and the project I will develop with your help is quite the only thing left before my graduate.
I will owe you so much beers, love you guys!!!