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Published on: August 15, 2013 / Comments: 2

Run your LEDs on AC power

... And not by using a wall-wart either!


Dealing with mains voltage is no joke, please be careful

Running your LEDs from AC voltage is pretty efficient, you can light up a whole lot of LEDs with little effort.  Most Christmas lights you buy nowadays already do this, but as Matt points out in the video they flicker a lot.  Matt decided to set up a bridge rectifier, and a capacitor to smooth out the flickering.  As shown on the oscilloscope those simple modifications make a huge improvement!

Of course you can’t just plug the LEDs into the wall and expect it to work (and not catch fire).  A little planning is needed.  By calculating the collective voltage drop of the LEDs in series you can run a lot of LEDs with very little current limiting.  Cool hack Matt.

  1. Fung says:

    So basically it acts like an AC to DC step down transformer.

    • Matt Heilman says:

      Well once the AC is rectified and the ripple has been removed, The DC voltage is actually higher then the original RMS voltage. 170vdc 120vac. but with the resistor it does drop the voltage across the LEDs,
      but that voltage will change depending on the impedance of the load.

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