This dubious electronics burglar alarm kit, which cost 50p at my local charity shop, kept me amused for a full 24 minutes. That's pretty good value ๐Ÿ™‚

By Julian

Youtuber, shed dweller, solar charge controller aficionado

13 thoughts on “Dodgy kit build: electronic burglar alarm with bad science”
  1. Avataaar/Circle Created with python_avatars Peter M says:

    Very funny video, Julian! I love it! ๐Ÿ™‚๐Ÿ™‚๐Ÿ™‚

  2. Avataaar/Circle Created with python_avatars Peter Jennings says:

    In your patent document, the anode is the rectangular box on the right, the grisd is the squiggly line in the middle and the cathode IS the filament. Very old symbology, but often found in old documents such as this.

  3. Avataaar/Circle Created with python_avatars fuzzyguy210 Bright says:

    Shorting the piezo is better for the parents. The batteries will run d down sooner so they will not have to hear it.

  4. Avataaar/Circle Created with python_avatars pleasecho2 says:

    I get it, Ein-O = I know. or Eight Inch Nails?

  5. Avataaar/Circle Created with python_avatars someoneonlylol says:

    To be fair this kit is meant to get children interested in electronics/science. If they wrote the actual description of it children wont understand it at all.

  6. Avataaar/Circle Created with python_avatars nonchip says:

    about not mixing the batteries: early 1.2V NiCads had both a … creative voltage and kinda random internal resistance, so you could mess them up when mixing them e.g. in parallel with an 1.5V alkaline (because that'd essentially apply a reverse current through the NiCad) or in series essentially try to charge it, resulting in the capacity of the NiCad to degrade etc.
    Not mixing old and new batteries is easy: you don't want your nice new battery to blow the almost-leaking old one. also you want multiple batteries for a reason, and not one new one that even gets its voltage dropped and/or current limited by the now essentially just being crappy resistors old ones.

  7. Avataaar/Circle Created with python_avatars Krisztiรกn Szirtes says:

    If you mix old and new batteries, the product turns on and the two batteries waste a ton of energy balancing out

  8. Avataaar/Circle Created with python_avatars GordieGii says:

    The design is based on a joule thief. That's why they said the inductor increases the voltage.

  9. Avataaar/Circle Created with python_avatars Andrew Walsh says:

    Would make a great decoy burglar alarm!!! Not. Maybe if you taped some red cardboard tubes on the side and poked some of the wires in, it might look like an IED. Lol. Actually thats a bad idea.

  10. Avataaar/Circle Created with python_avatars Dave B says:

    Hundreds of Londoner's each year are killed or seriously injured from mixing up new and used batteries. It can be very dangerous. If you use a choke coil to change the voltage flowing through the battery it can be safe to mix but only under adult supervision. The government should pass a law protecting people by making mandatory minimum sentences for people caught mixing batteries. PLEASE THINK OF THE CHILDREN AND DON'T MIX NEW AND OLD BATTERIES!!!!!

  11. Avataaar/Circle Created with python_avatars Fran Gรณmez says:

    Electricity does not flow at the speed of light, it's not even near. That's a very common error

  12. Avataaar/Circle Created with python_avatars Robin Browne says:

    Sounds like you've invented some kind of electronic bag-pipe. Better send it to Big Clive for analysis. :=)

  13. Avataaar/Circle Created with python_avatars djbare9 says:

    Even for a child's toy, that is a piece of crap, whoever put this kit together, needs to back to basic electronics and at least learn component operation.

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