This is another of those random weird products you occasionally stumble across on eBay. It's a shop-door "OPEN" sign that is based around an emergency light frame that isn't quite compliant with UK safety standards.
It also uses some quirky electronic design features including the use of discrete components (no chips) to keep the price down, and that just makes it a PERFECT teardown item.
Note that the very analogue control circuitry also cuts the battery off at about 0.85V.
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12 thoughts on “Weird emergency open sign???? with schematic.”
  1. Avataaar/Circle Created with python_avatars Brian Sutherland says:

    The latching part looks sophisticated. Looks like a logic algorithm. Would a solenoid be an alternative? Brilient interesting video. Thanks.

  2. Avataaar/Circle Created with python_avatars AA7YA says:

    The sign is an invitation to reverse engineer.

  3. Avataaar/Circle Created with python_avatars Isuru Athukorala says:

    This comment is after 5 years from publishing video. I got 16 'EXIT' signs to repair. Same PCB , and battery too. I repair only 1 yet. Battery get bad. And cap get reduce Value too. All thing could replaced but not battery. Only NiMH are available . So cant replace for the reason mentioned in video. I wonder i should modify it and put LiION battery.

  4. Avataaar/Circle Created with python_avatars tundramanq says:

    OPEN could be to designate the/an unlocked door. The NiCd battery should be easier to replace every 3-5 years with out destructive access. Planned obsolescence?

  5. Avataaar/Circle Created with python_avatars Frank Jackson says:

    I feel like there are eBay sellers that make specific stuff just for people like Big Clive to disassemble and reverse engineer.

  6. Avataaar/Circle Created with python_avatars Paul Watkins says:

    Immediately thought of Alice in Wonderland with the Eat Me and Drink Me as if it daring Clive to Open Me LOL

  7. Avataaar/Circle Created with python_avatars nigozeroichi2501 says:

    Eh, only three years late but, can see in the reflection off the glass, your bench looked like mine, covered in crap, and a tiny clean area to work😆

  8. Avataaar/Circle Created with python_avatars T3K says:

    funny enough the establishment my mother was a manager at could have benefited from an open sign like this because the power strip would get unplugged or turned of accidentally

  9. Avataaar/Circle Created with python_avatars Charles Murphy says:

    In third world countries where power outages are frequent, shops don’t close.

  10. Avataaar/Circle Created with python_avatars btd5 says:

    this sign is probably ment for 24/7 shops haha

  11. Avataaar/Circle Created with python_avatars Evan Fehr says:

    Does that white thing say AA? Like a AA battery? That's what it looks like

  12. Avataaar/Circle Created with python_avatars Chris Snyder says:

    Maybe it was a repurposed emergency exit sign

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