Re: Boost converter magic smoke caveat
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I had quite a few crappy-cheap Chinese boost modules, probably the same heritage as these. The poor decoupling I was prepared to live with, it's easy enough to add more, and you'd probably need to anyway, even if it was reasonable to start with. But one of my modules did something similar, smoke and a capacitor turning brown and about to burst into flames. It turned out the output voltage adjustment presets on all of them were poorly soldered. And if feedback on a boost regulator fails in the wrong direction output voltage shoots up to a theoretical infinite volts. I guess this is what happened in your case.
Check the connections of the 10-turn preset, that they are properly soldered to the pads and the plated through holes really are properly plated through. They are 'simple-switcher' designs so you can get data sheets easy enough to see what components should be around the device and the connections. Those simple-switchers are nice chips, and as they're quite chep are probably not likely to be forgeries. Can't say the same for the rest of the components on a cheap Chinese module, just be prepared to replace them.
Oh, and something else I learned the hard way, DO NOT use tantalum caps as extra decoupling where significant ripple current will flow - like the input on a boost regulator. That poor cap went all brown and started smoking.
In fact, you're not supposed to connect them across low impedance sources anyway - so no tantalums on 12V inputs!
On Fri, 27 Nov 2020 at 17:03, Neil Smith G4DBN <neil@...> wrote:
A brave experimenter chum of mine reports that they used a neat-looking