There’s no shortage of cheap & cheerful power supplies which you can obtain from a range of online retailers, but with no listed certification worth anything on them calling them ‘dodgy’ is more of a compliment. On the [DiodeGoneWild] YouTube channel an adjustable power supply by the model name BSK-602 is tested and torn down to see exactly what less than $5 off sites like Alibaba will get you.
Perhaps unsurprisingly, voltage regulation is very unstable with massive drifting when left to heat up for a few hours, even though it does hit the 3 V to 24 V DC and 3 A output that it’s optimistically rated for. After popping open the adapter, a very basic switching mode power supply is revealed with an abysmal component selection and zero regard for safety or primary and secondary side isolation. With the case open, the thermal camera reveals that the secondary side heats up to well over 150 °C, explaining why the case was deforming and the sticker peeling off after a few hours of testing.
The circuit itself is based around a (possibly legit) UC3843RN 500 kHz current mode PWM controller, with the full schematic explained in the video. Highlights include the lack of inrush protection, no EMI filtering, a terrible & temperature-dependent voltage reference, not to mention poor component selection and implementation. Basically it’s an excellent SMPS if you want to blast EMI, fry connected electronics and conceivably burn down your home.
Good grief, 150 Celsius? Sounds like it has a max rated output of 72 watts of electrical power; I wonder how many watts of heat it puts out? Certainly more than 72.
One of the diodes goes to about 190C.
That’s getting pretty close to desoldering its self and well above the glass transition temperature for the PCB.
I did one of these for a couple years now and I use it regularly and even had it hooked up running a 12 volt fan for a couple months without an issue, but I didn’t really pay very close attention to it but I think I’m going to go through it and see what’s what.
Just curious ( “hypothetically” of course), what would happen if:
(a). Someone formed an LLC
(b). Built a few units (like the one pictured), in a garage for a couple of cents on the dollar.
(c). Sell them online thru the LLC with a huge markup.
(d). Ignore customer complaints.
(e). Make bank (if “authorities” complain, do what crooked home improvement contractors
do (start a new company, rinse & repeat).
Forgetting all “moral” considerations, would this model work ?
That is exactly what all those Chinese sellers do on Amazon. Even right down to the name change.
Where in this day and age does.one obtain continuous form paper (edge perforated)?
Does not look too difficult.
https://www.bueroshop24.de/sigel-endlospapier-706630
The Sigel 12370 seems to be widely available at least in the EU.
We call it “kettingpapier” (chain paper) over here. It’s pretty much still available yeah.
Just search for “edge perforated continuous form paper” on Amazon.
Yikes, I was expecting it to be pretty bad, but that’s truly terrifying. What baffles me most is that the person who made this was not only educated enough to design and make a switch mode power supply that works (albeit badly), but yet also dumb enough to build this monstrosity.
For you or me it’s a monstrosity and accident waiting to happen. For some guy in China it’s a dinner on his table.
Chabuduo mentality fuhrer enabled by being unable to prosecute designers and manufacturers of this crap when it goes up in flames and burns down your house.