USB Power Delivery for Hobby Projects

I'm adding USB to projects just as a power cable but I'm (still) trying to avoid surface-mount.

The only USB connector I've found that is still through-hole is USB Mini-B so I am unfortunately stuck with that.

(I should mention I am building kits for hobbyists who are averse to tackling an SMD component — they make me nervous as well.)

I was hoping to use something like this for my Son's Christmas tree but it needs 33v. For some reason I cannot find ANYTHING to drive the lights on this tree. The old, broken power supply is labeled as 33v @ 800mA (26w) but all the power supplies I can find don't even come close. I tried ordering a custom one from AliExpress and it worked, for about 10 minutes, then it overheated and the lights started flashing.

I would much rather just use a standard USB-C power brick and run it through something like the boards you listed, but they don't seem to support 33v. Any help would be greatly appreciated.

I'm confused by the article; I use USB power delivery with USB-C all the time, and haven't hit the considerations it mentions. Set up a fuse and diode on the power out, set up the CC resistors, choose a footprint in SMT or THT as appropriate.

This has some of what you are after ? https://www.tikstation.com/product/mini-power-station/

Wanna make one, we could open source it? I have thought about making something similar before for driving VFD/Nixie tubes. There are a bunch of things out there that don't quite scratch the itch.

https://www.sparkfun.com/products/15801

https://www.adafruit.com/product/5807

https://electroniccats.com/store/catsink-usb-c-pd/

No, it's "5V is easy. Anything above that is not."

For obvious reasons. Almost everything can tolerate 5V. Very few things can tolerate 9V and above.

Consequently, you need a complicated dance in order to ensure that everybody agrees before jamming 9V, 15V or 20V down the pipe. That dance has enough complexity that effectively everybody uses a full-blown Cortex M0 with a couple of purpose built analog blocks to carry it out.

See: https://www.infineon.com/cms/en/product/universal-serial-bus...

I use a $2 PD trigger module on basically everything.

The only time I use 2.1mm is when I'm going to daisy chain or do something besides point to point, when I'm doing solar, or when I'm using the connector for something other than power(A voltage divider can protect your input from accidental power connection, so it's one of my favorite simple connectors).

Kind of like this? https://pedalcell.com

Device? No. Board design? Maybe, it depends on how good a relationship with suppliers you have and how much stock you pre-purchased to manufacture it.

Which is exactly why this particular problem is a lot more annoying for hobbyists rather than actual industry players.

Barrel jacks tend to have higher contact resistance than USB-C.

At least the Wii U can just be powered using a 15V PD trigger. The maximum current requirement of 5A isn't met, but works just fine. Since the Wii needs 12V I would add a DC-DC converter but I don't see any reason why it shouldn't work.

I mean, with all due respect, so? An OG ATmega-based Arduino is significantly more powerful than the AGC. A garage opener from a decade ago can easily be more powerful (MIPS-wise) than the AGC. I wouldn’t be surprised if that holiday candy box that plays music when you open it were more powerful than the AGC.

The reality of today’s MCUs is that you can get single-digit MIPS at the price of shipping, handling, and the plastic of the chip’s package. So you see those used where a handful of discrete logic would suffice, like before that you’d see discrete logic where a couple of relays and a handful funny-shaped mechanical actuators would suffice. It’s overkill in the sense that you don’t need nearly as much compute as you get, but it’s completely rational in that it’s genuinely the most cost-efficient approach.

You can also (and thank you STMicroelectronics and before that Atmel for getting Microchip off their collective asses on that) get ridiculous amounts of I/O to drive with that compute. Gobs of GPIOs with individually configurable driving modes? No problem. Multiple DACs and ADCs? Sure. I2C and SPI? You bet. Two or three UARTs? Gotcha, would you like some CAN with that? In a 24-pin package so you can actually use more than a couple of these? Ahh now that’ll be four times the price, please and thank you.

You know what’s also expensive? RAM and (to a lesser extent) ROM. The TRS-80 came with 4K bytes of RAM at minimum. The AGC had about the same computing power, 2K words of RAM and 36K words of ROM, and still the designers traded speed for program memory by writing a bytecode VM. The cheapest STM8S0, by contrast, comes with 256 bytes of RAM and no external memory interface; and I don’t even want to think about the obscure Chinese 6502 and 8051 clones you’ll find under the epoxy in toys and TV remotes. All that power and all you can fit in there is a glorified flowchart. But if you think about it as programmable logic, in the widest possible sense of the phrase, it makes perfect sense!

Also (and here I could be wrong), my understanding is that the software on the AGC couldn’t actually plan the mission—it could do some specific things that you can’t reasonably to by remote, like landing, but most of the math was done by much chonkier programs on much beefier machines. It was a controller in the purest sense: it could control the hardware to achieve what you wanted, but you had to tell it precisely what, it didn’t figure it out for you. So if anything goes wrong and your comms are busted, you die.

Don’t get me wrong, the AGC is bloody impressive. (Transparent native code / bytecode interworking anyone?.. None of those words were even in the dictionary back then.) But through equally impressive efforts of other people, its computing power was table stakes within a decade. Nowadays it’s a rounding error in your bill of materials.

ETA: Ah, I see, the argument is that the Cortex-M0+ in question is superior in MIPS, RAM, and ROM. Yeah, that’s more reasonable. Low-end Cortex-Ms can also be very cheap these days[1], provided you can source them.

[1] https://hackaday.com/2023/02/16/puya-py32-the-cheapest-flash...

There's probably a commentary there about the compute being less important than it being attached to the most powerful rocket ever built.

Not an electrical engineer but I dabble; I believe it would be because center positive could have electric current going to the battery before the ground connection is made. Center-negative would guarantee the ground connects first. {edited} Based off a quick Kagi search and reddit results guitarists use center negative connections and most wall plugs provide center positive, but I don't really know why.

I wondered about that as well. My best guess is that it's something to do with which pin makes contact first in the barrel, and having the battery parallel to the barrel's contacts, it might matter which one contacts first (though I can't think why).

I mean, that's the whole point why I decided to go down the rabbit hole of spending time to learn and understand it instead of just grabbing the cheapest AliExpress trigger board and hope for the best.

Giving up on understanding and documenting it is not going to improve the situation, we'll just end up relying on a handful of manufacturers that are the only ones able to supply what everyone else built upon… and the chip shortage of 2020/2021 pretty much has shown how bad that can get.