Smoke release!

[paulca]

Thought I'd share this.  You buy cheap chinese stuff and 9 times out of 10 it works fine.  Then there is the one.

https://www.ebay.co.uk/itm/USB-Power-Breakout-DC-to-DC-Power-Module-Micro-USB-5V-to-1-8V-3-3V-5V-9V-12V/311932552254?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2648

Powered it up, fine. 
1.8V was 1.801V
3.3V was 3.26V
5V was 4.99V
9V was 8.89V

Switched it to 12V

Glow, sparks, smoke.  The little 6 leg chip just up and right of the 9V/12V switch lit up orange, then yellow, then white and smoked.  I pulled the plug after glancing to see it drawing 1.5A current on the USB analyser.  So a 1.5A short circuit current through that poor little chip.

Plugged it back in and now:
1.8V was 1.801V
3.3V was 3.26V
5V was 4.69V
9V was 4.5V
12V was 0V

So I figure the chip is (was) part of some form of boost circuit and is now no more.  It looks like it was boosting whatever regulates the 5V, 9V and 12V outputs as 5V also dropped.

Still, I only bought it as a gimmick to play with.  Thought it was a nice way to get low current range of different voltages from USB. 

So my score for yesterday is 1:1 evens.  I killed a power supply gimmick module, but I also fixed an old Innokin CoolFire IV eCigarette mod which my ex dropped and while it powered on it flashed fault lights when you attempted to use it.  Took it apart and found the sense register had a cracked solder joint as it looks like the 18650 cell slammed into it when dropped.  Quick resolder and it now works again.  Win!

[WaveyDipole]

I recently had one of these meters go up in smoke:

ttps://www.ebay.co.uk/itm/10A-0-100V-voltage-meter-and-LED-DC-dual-display-digital-current-home-garden/391849081750?hash=item5b3c067b96:m:mIzVQQemqxMhdUnk8vVwc6Q

It worked just fine but one day when I powered it on (using a supply voltage that was well within the specified range) an IC just let out the magic smoke and the thing died. No fizz bang and no obvious reason. Once faild, an excessive current draw was evident.

Most of these far east modules do seem to work OK but given how cheap they are I have learned not to expect too much from them. These meters, for example, are rather inaccurate and can serve only as an indicator at best. It seems that every now and then one of these cheap modules will just fail unexpectedly for no apparent reason. I guess that's what you get when something is made to a price point, there is a lack of any kind of quality control, and the sources of components are questionable at best. Its a bit pot luck.