7805 FROM HELL

AAARRRRGGGHHHH!

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This is the 2nd time one of these little pieces of shit (WingShing 78L05) has failed within normal range of working parameters. Absolute maximum input voltage is 30V, I was feeding it with a clean 24V and was rewarded with instant smoke and the inevitable olfactory pleasure that comes with it. It still stinks after opening all windows for 10 minutes.

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Yet again I’ve lost one ATtiny13A micro-controller because of these shitty devices. Fortuitously I had ONE spare micro and one spare 78L05 (genuine ST). I was also lucky that the dying voltage regulator didn’t kill more than just the micro. At the time of failure a couple of other more costly boards were connected. They survived.

The remaining 100 or so of these WS7805 went into the recycling bin. No more ebay experiments with this brand.

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6 Responses to 7805 FROM HELL

  1. ubi de feo says:

    sorry to hear.
    I almost never make mass purchases of components, as none of my projects went beyond the 150 units, but I prefer to stay on the safe side, so for my regulators I mostly use TI.
    and…
    I wouldn’t feed 24V to step down to 5, despite the ratings.
    I’d go in two steps to add more protection, but I’m not exactly an engineer, so I’d rather wear a helmet :)

    • robert says:

      There was close to no load on the regulator, certainly below 10mA. It should survive that. And if it gets too hot, then go into thermal shutdown instead of exploding. It’s simply a piece of crap.

      I bought this bag of regulators because it was seductively cheap and its always good to have a few of 7805s around. Turns out these were too cheap. For the price I payed due to destruction of other boards, I could’ve gotten many not so cheap ones.

      No more WingShing for this guy.

  2. ubi de feo says:

    and I’ll save your precious advice for the future.
    I really enjoy your blog, by the way.
    been following for a while now :)

    cheers
    ubi

  3. Ah! Sorry to hear that. Finding good suppliers from eaby is a tricky work!
    Sometimes the components I order from ebay are very reliable and sometimes they just make me sad! Usually going for very very cheap components will do no good to our projects than making it a hell!

  4. SeanB says:

    Looking at the datasheet they only actually work up to 20V, that they survive to 30v is only going to be a guess. They only spec operating conditions in the datasheet to 20V, so they probably only are actually 20V rated parts inside.

    • robert says:

      One could get the impression that might be the case. I’d have appreciated a nicer failure mode though. Failing open instead of shorted for example. But no…

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