#yumcha — Public Fediverse posts

Well, this is annoying.

I have some little power #modules (bought on #AliExpress, natch) that were advertised as automatic boost/buck converters. Input from <4V to >30V, output from 1.25V to 35V.

They're based on the XL6009 switching converter, which supports auto-buck-boost as one mode.

But they appear to use it in boost-only mode. The output voltage can not go below the input as far as I can tell. From the datasheet, it looks like that's because the auto-buck-boost config requires a few more components, plus a transformer instead of a simple inductor, which is probably the main reason (BOM).

The listing just seems to be ... wrong.

Annoying.

#seller #SellerDescription #YumCha #Chinesium #BuckConverter #BoostConverter #AutoBuckBoost #BuckBoost #electronics #hobby

Continuing on the "Hangell" switching bench power supply I received a few weeks ago...

I mentioned there was some switching noise visible on the output - not a lot, but more than I'd ideally want. Today I built a filter for its outputs, with a large-ish common-mode inductor/choke rated 10 mH (accurate enough, though my meter says it drops to about half that at 100 kHz) sandwiched between a couple of 1 μF class X2 safety capacitors.

It seems to have done the trick. Under a moderate load, all the random hash has disappeared, leaving only some spikes at the switching frequency, and those are much smaller than they were before. The RMS noise value is now (barely) under 1 mV, if you believe my cheapish oscilloscope.

Like a lot of switching supplies, there's a lot of open space in the chassis, so I had room to squeeze the filter inside. I'm pretty happy with it!

Now to see if this no-brand thing works for any length of time.

#YumCha #SMPS #PowerSupply #SwitchModeSupply #Hangell #bench #workbench #noise #filter #electronics #hobby

@ZenHeathen

Princess Auto is basically container-loads of cheap Chinese stuff dumped into a retail environment, with a smattering of other stuff mixed in. Some of it is junk, a lot of it is serviceable if not great, and there are a few gems mixed in here and there. A lot of it will be the same junk sold for three times the price at Cambodian Tire (marked up 5x, but permanently "40% off!", of course).

Weird tool you'll need once or twice? It's a good place to get it. Inexpensive hydraulic stuff, or a cheap small engine, or blasting beads, or brake cleaner? Sure. Hand tools you'll use all the time? Buy very carefully, and probably from their "ProPoint" "premium" line, not the regular "PowerFist" [1] stuff.

[1] Honest, this is their house brand, I swear.

#PrincessAuto #PowerFist #ProPoint #Chinesium #cheap #YumCha

Line manager: Uh, Boss?

Boss: Yes?

L: We finished that new run of the component. We sent it to QA.

B: Okay? Is there a problem?

L: I just got the report back. This batch, uh, didn't meet the tolerance goal.

B: [rubs temple] Okay, shit happens. I guess it goes out as 10%. That's not too bad a hit.

L: Uh, it didn't meet 10% tolerance, either.

B: What? How bad is it? 20%?

L: Uh...

B: It's *worse* than 20%?

L: Most of the parts are barely within 50% tolerance.

B: ...

L: So, uh, we should probably ...

B: Who was running the line?

L: ...

B: It was Chuck, wasn't it?

L: ... yes.

B: Was he drunk again?

L: I don't know. I sent him home.

B: Nobody's made these components in 50% tolerance for thirty years. Where am I going to sell them?

L: ...

B: Okay, AliExpress it is. Go to the noodle shop across the street and offer him some new boxes if we can have the ones his supplies come in. No way I'm putting these parts and the company name in the same room together.

(inspired by some parts I received today...)

#electronics #hobby #AliExpress #tolerance #components #ShortFiction #qwality #ShipIt #scene #business #Chinesium #YumCha