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Simple LED Circuit — Parallax Forums

Simple LED Circuit

NWCCTVNWCCTV Posts: 3,629
edited 2010-10-17 20:38 in General Discussion
I need to accomplish the following using the absolute minimum of parts. Will be using low watt (1.2-3.3V) LED. I want to be able to light an LED when a magnet makes contact with a piece of metal.

Comments

  • bill190bill190 Posts: 769
    edited 2010-10-17 00:18
    Perhaps a Capacitive Sensor would work? Here is info on that...
    http://en.wikipedia.org/wiki/Capacitive_sensing

    Also there are pressure sensors sold at the Parallax store. And a reed switch which activates when a magnet is nearby. See the sensors area here...
    http://www.parallax.com/Store/tabid/60/Default.aspx
  • LeonLeon Posts: 7,620
    edited 2010-10-17 02:44
    If the magnet makes contact, it could simply complete a circuit. No additional components required!
  • RagtopRagtop Posts: 406
    edited 2010-10-17 06:50
    I think they want the light on when attached to any metal object and off when unattached with the battery attached to led/magnet.

    Maybe if the led/magnet consisted of two magnets insulated from each other. Ground wire from battery to one and led ground wire to the other. The metal object might complete the circuit.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-10-17 11:02
    The metal object might be painted, though. Anyway NWCCTV needs to clarify where the magnet and piece of metal are relative to the circuit containing the light.

    -Phil
  • NWCCTVNWCCTV Posts: 3,629
    edited 2010-10-17 11:55
    The magnet would be on a flat surface. A ball will contain the LED and when the ball contacts the magnetic surface the LED will light. Thanks for the posts. I think I have a starting point now. Oh, and Ragtops theory is correct.
  • ercoerco Posts: 20,260
    edited 2010-10-17 14:06
    So no HiFi, WiFi, 4G, Hotspot, iPhone, Bluetooth, Quadcore, Propeller, Blackfin, AVR, PIC, Arduino, dongle, or GPS cross-referenced to a database of every metal object known to man?


    Not even a Stamp, USB adapter, solar cell, shift register, or relay?


    You mean like a magnet and a switch???





    Sheesh. That's hardcore.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2010-10-17 19:51
    Yep, Like a magnet and a switch. Small, cheap and simple!!!!!
  • FranklinFranklin Posts: 4,747
    edited 2010-10-17 20:13
    Sounds like a reed switch is what you are looking for.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-10-17 20:38
    I'm still confused about where the magnet is. So let me see if I understand: you have a ball (steel?) with a battery, an LED, and some sort of switching device. This gets stuck on a magnetic surface. Or is the magnet in the ball, and the ball sticks to any steel or iron surface, e.g. refrigerator door? A drawing would certainly help.

    -Phil
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