So today I decided to sit down and work on a few little projects. I started by working on a PWM controller board I wanted to make. That went up in smoke (literally) after a few poorly chosen component values. But that was an experiment I knew it probably wouldn't work.
However I followed that up with the most annoying thing I've ever done to myself. I'm busy working on a 2-3 cell, 4A buck driver. 90+% efficiency. Nice and small. I built it up, connected it and plugged everything in. I got a whimper of some light and then nothing. I scratched my head, checked everything over and replaced the busted IC. Fired it up and this time I got some continuous light but definitely not 4A. I tried 3 cells and it basically blew the top off the buck IC.
What. The. Hell?
I then spent the rest of the day checking my CAD drawings, circuit diagrams and the PCB itself for shorts. I could not figure it out. After about 5hrs of screwing around (plus a break for lunch) I did something I had oddly not already done. I took everything off and re-flowed the whole board again. Then it hit me. See the inductor at the top of the board? How it's all nice and aligned with everything else?
It goes the other way!
And that right there is why I need to put my visual design tendencies aside when I'm building circuits. In my moment of "it's gotta look pretty" I completely neglected to put the stupid part on the right way. The inductor was basically doing nothing. I'm actually surprised the circuit lit up at all the second time!
Not very exciting I know, but I had to share because it took me literally all day to work out, gave me the worst stress headache ever, and got me seriously frustrated.
The little things always get me too. Pretty sure I’ve got several repressed memories of long, painfully annoying days all due to a simple 10-15 second fix. At least the feeling after finally fixing it is amazing.
I like that you didn’t just chuck it and quit. My last project is not even in the same league but it did smoke very nicely and has been waiting almost a week for me to get back to. Tenacious is good.
I got the shits at about 2 in the afternoon, and the headache knocked me around. But after a few Aspro and a few minutes just "chillin" I went back to it. I couldn't leave it alone and absolutely had to know what I was doing wrong. I should have got the hint the first time I installed the inductor now that I think about it - when reflowing inductors I normally put some paste on the pads and sit the inductor half on, half off the pads. As the solder melts it sucks the inductor in place. So the inductor actually slides across the pads into position. This didn't happen so I gently pushed it into place. Now it's obvious why!
I've done the LED backwards/twisted thing multiple times as well. Usually when my mind is elsewhere.
Nothing to see - It's single sided apart from a few traces. It has no controller circuit on it at the moment, but I could probably incorporate one and fit everything on the one board and maybe keep it under 17mm too. I haven't tried yet though as my initial intentions were to make it a PCB stack with a separate driver board and controller board. The board you see in the pictures is 20mm in diameter, but that ground ring is 2mm thick.
I feel your pain but for different reasons (I know very little about electronic components). So this driver has only the one mode at the moment? I’m also loving your work here and elsewhere.
Single mode yes but a separate wire for the DIM pin. Making it single mode is as easy as connecting VIN to the DIM pin. Making it multi mode is as simple as connecting the DIM pin to a PWM signal. I'll test it with Qlite driver as the PWM signal at some point this weekend.
17mm would rock the flashlight world, even if you had to add a separate contact plate. If you used a post for B+ it might save enough room to avoid that and put the Attiny package all on the backside.
Cool driver and I’m glad you figured it out before going postal.
It always is the simplest thing that gets me too. I can be putting together the most complicated mod and something simple will trip me up. I’m convinced it’s because I think so hard about the complicated part that I take the easy stuff for granted and miss something simple.
SSDD, as has been said already, when you’re really really making sure the big stuff goes right, the little stuff bites ya in the bobo.
First time I crossed an emitter was on my first Triple. I was being SOOO careful! Then one of em wouldn’t work…blew me away. But but but… then I saw that tiny little black mark on the positive side of the board. Ah crap!
I’m sure he’s fled the country by now, if that’s any consolation 0.o.
Rockets are extremely complicated things though, while I would have expected a more rigorous testing procedure this does happen pretty easily.
They are pretty delicate sensors capable of detecting slight changes in elevation and moment, often a part of other systems. It’s a lot easier to mess that up than say, installing a car engine upside down.
On a similar aspect, I installed my 219 pill in the other day and in the process ripped off an IC, the positive driver wire and trashed the 219 while taking it out. No idea how I was that destructive with pliers, but I evidently was. :~
