Ask Hackaday: Troll physics edition

[Martin] sent in two videos he found while cruising the tubes. The first video is a simple circuit with a resistor, three switches, and three LEDs. All the components are soldered together right in front of the camera. When a battery is connected, turning the first switch on makes the first LED light up. Turning the second switch on makes the second LED light up, and the same thing goes for the third switch and LED. Obviously we’re dealing with powers that are incomprehensible with even several cups of coffee.

The second video features the same resistor/switches/LEDs, this time in a parallel circuit. Turning on the first switch makes the first LED light up, and the second switch makes the second LED light up. Truly we are dealing with an expert in troll physics.

This is probably something really benign and uninteresting, but it sure is enough to wake up enough brain cells on a Monday morning. We’re not going to hypothesize, so check out the comments where we expect the correct answer to be.


Comments

  1. Thomas Dekker says:

    If the battery is modified to supply an AC signal, the switches can convert this to three signals:
    One LED works on +DC.
    One LED works on -DC.
    One LED with a series capacitor works only on AC.

  2. Piemaster says:

    Has no-one noticed just how chunky that “resistor” looks? Assume the resistors are SMT onto each LED, then what could you fit inside that resistor? DC-AC converter of some form?

  3. War_Spigot says:

    I recently bought some leds that said they were RGB(thats eBay for ya. Each one actually had what seemed to be a very small µC and one red, one green, and one blue led. It flashes, blinks, and fades in a preset pattern. Maybe something like this is being used here.(I looked at the µC under a loupe and could see no identifiable markings, and the eBay listing had nothing either, so don’t ask for info on it). They have only 2 pins like normal LEDs, they look no bigger than a normal LED, and the µC is visible only if you look very closely at it. If he has one with an analog pin on it or something of the sort…

  4. War_Spigot says:

    I recently bought some leds that said they were RGB(thats eBay for ya. Each one actually had what seemed to be a very small µC and one red, one green, and one blue led. It flashes, blinks, and fades in a preset pattern. Maybe something like this is being used here.(I looked at the µC under a loupe and could see no identifiable markings, and the eBay listing had nothing either, so don’t ask for info on it). They have only 2 pins like normal LEDs, they look no bigger than a normal LED, and the µC is visible only if you look very closely at it. If he has one with an analog pin on it or something of the sort…
    Sorry if this double posts, it doesn’t seem to want to post my comments…

  5. davidcr125 says:

    This is what I imagine is happening here. Assume V+ is an AC source with a DC bias, LED1 and LED3 light from the + and – half wave of the AC and LED2 from the DC component. Remove a part of the source (via the switches) and that LED turns off.

  6. Patrick says:

    Troll face would say:

    Problem technician ?

    or

    Problem energy company ?

    I think I go with diodes and ac current. And that the switches are not what they seem.

  7. Terry says:

    If the LEDs are actually Tri-LEDs dipped in red ink, they will appear to be off when glowing blue or green. They will only light up when biased up for red. So the modified switches only have to have appropriate resistors to provide the right forward voltage ranges.

  8. Andy H says:

    Here is a possible solution.

    Three self powered oscillators in each switch (think small watch battery(s) + 2 transistor multivibrator), each on a different frequency inductively coupled to the loop formed by their secondaries, and the secondaries of the three “leds”.

    The three leds are tuned circuits, tuned to the three frequencies.(think simple crystal set with the diode in this case being a genuine LED, might not even need a load resistor if the signals are creatively set at the correct power levels) inductively coupled to the loop, to pick up the frequencies being propagated round it by the three oscillators.

    The battery is genuine enough, but it does nothing, since the battery snap is insulated, and has the red and black wires joined together, to complete the loop.

    It might require some carefully hand wound inductors, or possibly an off the shelf smd rf transformers.

    In short the whole thing is a series of transformers, in a loop, signals are injected into three of them, signals are received by the other three.

    Simple, entirely AC, and very clever.

  9. War_Spigot says:

    The LED’s could definitely be modified. I bought some “RGB” LED’s from eBay which were really LED’s with a a red LED, a green LED, a blue LED, AND a uC. Each one had a super tiny uC in it wired to the LED’s. It had 2 pins, and when powered, the LED faded and flashed between different colors, yet it looked no bigger than a normal LED, and the uC was so small you could only see it when looking very closely at it. eBay listing had no datasheet.

  10. Bearface says:

    If anyone was wondering, the guy posted the solution.

  11. Damian says:

    Here is the link to the solution… which was not camera trickery afterall.

  12. doku says:

    I’ll just leave this here.

  13. karlos says:

    This project got me thinking :)
    Nice set up makes you think outside the box. LED’s are very illustrative!

    Simmular project: http://www.pa-international.com.au/index.php?option=com_content&view=article&id=134&Itemid=173

  14. Casplantje says:

    Those are truly evil components… I love it!

  15. the jones says:

    unfortunate, he’s not breaking the laws physics (actually that’s probably a good thing), he’s just using properties of AC currents and some really, really small components. as seen in his solution video:
    http://www.youtube.com/watch?v=mzDTZuFJYX4&feature=mfu_in_order&list=UL

  16. melvin goldstein says:

    Numbers are the Supreme Court of science. However Godel proved that we may not prove everything. Physics needs numbers. There must be Physics Foibles!!

  17. for the love of god.. says:

    it’s a troll vid… Edited.. to confuse.

  18. fsaad1984 says:

    Old post but still interesting to see the solution:

  19. Just and FYI says:

    I just want to share that anyone who thinks the three LED video is adobe after effects is ignoring the glow on the persons hand! The point in this is to think, not to take the easy way out.

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