I need someone to explain this to me.

Automatic capacitor charger lets you have fun with sparks

[GranTotem] is delighted by the sparks put out when a capacitor is rapidly discharged. But he’s not impressed at the relatively slow process of connecting them to a power supply for a recharge. So he built this auto-charging station for his capacitors that provides a shockingly good time almost continuously. Check out the video to see what we mean.

We always like to see the guts of the project, and that’s why we chose this image for the feature. But when everything is properly seated in the project box [GranTotem] has managed to achieve a really clean look. There are two barrel jack connectors on the end, one for 16V and the other for 20V inputs. The lid of the enclosure hosts an on/off switch, adjustment knob, and two banana connector terminals. Once switched on, a relay connects and disconnects the capacitor from the power supply at regular intervals which are adjusted by the knob. Just connect a couple of probes to those banana terminals and let the sparks reign down.

Comments

  1. Nuno.S.Almeida says:

    That relay will last for a week. Next time use a properly protected mosfet.

    • harviecz says:

      And inductance to produce higher voltage :-)

      I guess even single relay with high-voltage diode can be used to produce all. Oscilations, switching and inductance to produce high voltage. But it’s better to use mosfet and separate inductor :-)

  2. Electroalek says:


    Nice, but why two power supplies?

  3. Electroalek says:


    Just use ATX PSU

  4. Tim says:

    Agreed, the relay is probably arcing inside, and it it quite possible this will NOT work at higher voltages, especially at higher speeds when the relay just draws a continuous arc and then proceeds to catch fire. Smaller mosfets would probably also explode with larger capacitors/higher voltages. The best thing to use is an IGBT from a motor controller or something. But those can be hard to find.

    For larger sparks, you could use a mosfet as the switch on the low voltage side of a spark generator based around a car ignition coil. Then you could still control the speed of spark repetition, but you would get much longer sparks, without the need for an expensive capacitor bank or high voltage switch

  5. Natalie says:

    humm,
    for HV switching look up a spark gap switch. I was using 2 brass doorknobs and an auto ignition coil to initiate the spark to switch a bank of a few uF at about 6kV. it would vaporize metalized mylar strips with a deafening bang. it was all in a polycarbonate box with a remote trigger and various voltage on indicators.

  6. GranTotem says:

    Thank you guys for the advice I sure will take it in consideration.
    Now to Nuno.S.Amelda, is it just me or your comment seems a little bit aggresive?
    I Chose to use 2 power supplies because I didn’t want the regulator getting too hot inside, so a higher voltage for the caps and a lower voltage for the 555 circuit.

  7. Ever heard of an SCR? Plenty good enough to dump that energy in the name of science

  8. I did something similar a few years ago with some disposable camera guts and an old ipod touch box. http://www.thebestcasescenario.com/forum/showthread.php?t=18211

  9. Stanley Wu says:

    This post is weird and interesting at the same time. I mean, why would you want to see sparks when charging? But I think that indicates speed so it’s good too.

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