Yet another rant about crappy electronic designs.

Just now I was cleaning my desk and stumbled upon some old hard drive in a caddy that I still had laying around.. I figured, let's plug it in and see whether the drive still works. And to some extent, it does! Except that every few minutes it craps out on me. And after disassembling the caddy, I think that I know why.

Just as background information, hard drives work at 12V and generally require about 10W to spin their motor. Meanwhile USB operates at 5V. So a boost converter needs to be present in the controller to step up the voltage and power the drive.

Now what's a boost converter? It's an inductor, a capacitor, a transistor and a diode in a specific arrangement (if you're interested in the design, check out https://youtube.com/watch/...), along with feedback circuitry to stabilize output voltage. Now that transistor is important.. it switches at very high frequency, and its rise and fall times create heat. In the particular transistor used in that controller, it apparently causes the transistor to operate at 65-68°C. That's quite toasty IMO, and overheating may be why the controller is so unstable. But the Chinese manufacturers thought that it's just fine and okay to be sold without heatsink or some research into transistors with better rise and fall times.

So the hard drive craps out on me and yet again it's because of certified shitdesigns. MOTHERFUCKTURERS!!!!

The resistance of the transistor combined with the high currents produces the heat. 😉
Are you able to put a heatsink on it?
What also could help is replacing it with a low RDS(on) tranny with low rise and fall times.

68 °C sounds OK, though. Keep in mind that lower rise and fall times might reduce the switching losses but can lead to EMC issues.

@PonySlaystation Aren't transistors pretty much a short when the gate is powered though? I mean, a resistance of a few milliohms can't possibly generate so much heat, even at high currents. I think I can put a heatsink on it, but it's gotta be a very small one, or make a hole in the caddy where the heatsink can breathe a bit... I've got only 1-2mm of height and about 1cm of width and depth available. Currently I don't have anything that would fit it. Perhaps I can replace it with another transistor with a lower RDS(on) though.. looks like the transistor is in a standard SMD package so fitting replacements should be easy to find.

@7400 Hmm, I see. Perhaps I'll have to investigate further to see if it really isn't a problem with the hard drive.. it's already quite old after all. As for EMC, I guess that I could wrap the caddy in aluminum foil and ground that?

@PonySlaystation @7400 wait no.. it's an AMS1117 which apparently is a regulator. That explains the heat! But why the fuck would they use that over a boost converter? Mind-boggling.

@Condor Yes, they have a low resistance in the milliohms mostly, but during the transition to blocking, the resistance rises (although very quickly). But a big factor is, that in DC-DC converters the transistor is there to make quick "shorts" so the inductor has a steep ramp (U ~ dI/dt). This high current combined with the low restistance still creates some powerlosses to heat.

@Condor Linear regulators are often used when there are emc problems you cant get rid of, but as you said, DC-DC converters are much more efficient, some up to 95%.

@PonySlaystation Hmm.. I see. That's essentially what I meant with those rise and fall times. By the way, even when detaching the hard drive and only plugging in the controller, this regulator as well as the brain box apparently get uncomfortably hot, and the controller still frequently disconnects itself. I think that the regulator might be just a cheapo solution to drive the brain box in there. But that regulator steps down the voltage from 5V to 1.2V.. a 3.8V drop!!! Never mind the 12V boost converter, even just powering the thinking electronics causes it to crap out! Fucking hell.. this is gonna go straight into the garbage!

@Condor They don't. A linear regulator's output voltage can only be smaller than its input voltage, while it's the other way round for a boost converter. The 1117 (a jellybean part BTW) is probably used for the 3.3 V rail.

EDIT: Okay, you already measured the output voltage. But yeah, a LDO is much cheaper than a switching regulator and it's thermally still feasible, so they're going for that solution.

@7400 aha. After probing the output voltage it seems like it's a 1.2V regulator though.. no idea what they're using it for but meh. What's a jellybean part though?

@Condor It's a core voltage for a microcontroller or for some other logic. Most microcontrollers just have internal voltage regulators, that's why they're usually powered just from 3.3 V.

A jellybean part is just a part so common you'll find it almost everywhere. The 1117 is made by a lot of manufacturers in a few different packages (and fixed output voltage variants).

@Condor
Fuck the drive.
Unscrew the plates, glue a sand paper with double tape at the bottom plate (or find longer screws and use a CD rom, you can discard or even have different sand papers ready)
The CD part is my adaptation for the DIY YouTube versions, as I'm a cnc machine operator I can fix drill blades and other cutting tools with it. Very very handy.

Oh and for CD Roms I'm doing at least two cnc machines, one for cutting, other for engravements. Maby I'll make some money out of it

@GyroGearloose Why would I want to destroy a perfectly good drive though? It's just the USB to SATA controller that constantly craps out on me. The drive would still be perfectly usable as an internal drive in e.g. my server though. I think that I've still got 2 SATA ports and one Molex connector for that.. just gotta break out that Molex connector into a SATA power connector, but I don't want to just destroy it..

@Condor oh... Well I'll leave the tip then :p going to start my DIY page after vacations, would appreciate tips and ideas like this

@GyroGearloose Currently I'm mostly working on some basic stuff like making good quality audio cables etc. For that I'm using a metal audio jack, some electrical wire (28AWG, good for 1A) on each pin and then sleeved it up with the sleeve of an old Ethernet wire. Currently I've done one end on that wire.. not sure what to put on the other end yet but probably that's also gonna be a male jack.

Other than that.. eh, I don't have much inspiration for projects at the moment really. Earlier I did something on the breadboard where I could generate a sine wave from an LM324, some resistors and some caps, but since I didn't have the proper caps the sine wave didn't look very clean. I'll have to order the right ones and improve that later.. but if I could route that signal to somewhere else (some engineering channel explained something where you'd compare it against a triangle wave or something like that) and if I can get high current on the input, I could then send it off to a transformer to get 230VAC on its output. Then I can do testing from there, without stressing the mains circuit and mostly my landlord too much.

Oh also that audio wire.. I think that I'm gonna build a MDF box for it with just some female to female jacks for the 3.5mm audio, as well as a breakout for the USB port at the bottom of my AIO computer. Acer being the certified enganeers they are put the USB port in there all the way in there, with a very deep indent. This makes that none of my conventional USB devices can fit snug in there because their male USB jack is too fat. So I'll have to use one of my USB jacks without the plastic casing, jam that in there and wire that up to a socket in that MDF box. Then I can work from there without that stupid indent.

Below is a picture of the audio wire so far :)

Ohhh OK then.. I'm teaching the master I see... I know now who to pester with my projects :p

@GyroGearloose Currently a student/hobbyist at best when it comes to electronics, but yeah feel free to :) I'm very interested in DIY projects of any kind, be that electronics, mechanics or anything really. As for electronics, @7400 knows way more about this subject than I do :)

Well, this was my today's DIY project...
Crossbow in vacations... Straws, sticks, hot glue and tape

Fucking pic bug

@GyroGearloose Not bad! How does it perform?

Not well yet...
First the frame was week, I reinforced.
Then made a trigger , didnt work made a better one.
Finally it shots (like 10 meters straight) but I burned the guide (straw with hot glue), so I made another.
Tomorrow, a boat... Meanwhile I get to explain lotsssss of shit to the kid, and he listen to me because it refers to the new toy...

Btw he knows more then me (a lot more) about the DC and marvel universe and didn't even know that Thor, Zeus and such were gods from the history...
Guess who got a lesson about geek mithology (the little I know) while talking about movies... Hehehe

@Condor @7400 @PonySlaystation
I’m now officially subbed to all of you. May you all continue to have interesting electronics projects that teach me many things.

@Diactoros hahaha, thanks bro :D
@AlexDeLarge recently tagged me in one of @smit-happens as well.. the content from there was really interesting too! Apparently they're working with PCB's as well. Personally I'm eagerly awaiting more electronics content from there :D

@Condor Glad to hear! I have a ton of content from my circuits and capstone projects I'll be posting more of! :)

@Diactoros Thanks! I hope I'll have more time to post soon. In the meantime you're welcome to tag me if you have open questions on analog or embedded stuff ;)