I built an AC power supply (we called it a TENG) based on the tribo-electric principle. It can light up about a hundred 3 mm LEDs.

Now I want to try supplying the power from my TENG to an LCD thermometer or a small calculator.

As far as I know, I need to install an additional capacitor to the circuit to make it work, but I do not know how to choose the correct type of capacitor.

I will purchase the 400 V type, but I have no idea about the capacitance difference. Would you please teach me how to connect it to the circuit?

I attached an image of my circuit:

enter image description here


1 Answer 1


400 V is probably excessive. The voltage on this capacitor is not determined by the open-loop output voltage of your TENG, but by the amount of current generated, current consumed and the capacitance value.

With a load attached, the voltage on the capacitor will not rise much, and you can place a Zener/TVS diode in parallel to your capacitor, to limit it, too.

E.g. your load needs 3.3 V:

  • Use a high value capacitor, e.g. rated for 10 V
  • Place a ~5 V TVS diode in parallel to capacitor and load.
  • \$\begingroup\$ Oh, I think actually, my device's current is extremely low, maybe around 100 nA-15 uA, Open-circuit voltage is about 250 V. And the load means the power required to operate the electronic devices that I mentioned above, doesn't it? And can you please give me some 5V diode names? I have several 1N4007. \$\endgroup\$ Sep 20 at 7:12
  • \$\begingroup\$ If the device outputs only a few µAs, then how are you lighting 100 LEDs ? Are they actually in series ? Or I am misunderstanding something. If the generator provides only miniscule current at high voltage, then what you need to power any low voltage electronics from it, is not a capacitor, but a power converter (e.g. Buck converter) \$\endgroup\$
    – tobalt
    Sep 20 at 12:51
  • \$\begingroup\$ Yup the LEDs are connected together into a serie, maybe I measured the wrong value of current but I think it could not be higher than 50 uA. I read about the Buck converter, and its uses is to make the current runs smooth, isn't it? \$\endgroup\$ Sep 26 at 1:08

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