About: PLC, Arduino - Do it yourself project

Today I would like to share how to light up the LEDs by wireless power transmissions from a toothbrush charger and solenoid valve coils which were picked up from the scrapyard.

Before getting started, please watch the video below:


The main components are as follows:

  • 01pcs x toothbrush charger. My kid's toothbrush was damaged and only its charger is remained. Its specification: 220 - 240V~, 50 - 60Hz/ 1.3W.
  • 01pcs x 24VDC solenoid valve coil. I had 2 set of valve coils which I picked up them in scrapyard.
  • 02pcs x Resistor 1K.
  • 20pcs x LED.


Firstly, before applying this testing, we should learn about wireless power transmission and how it works on google site or on this instructable page.

Soldering 2 resistors 1K at the valve coil terminals. My valve coils size are about (WxDxH) 22mm x 30mm x 30mm, capacity 1.7W and 3.0W. It is lucky that the valve coil's hole (diameter ~9mm) fits into the charging tower. See picture below:

Soldering the LED to these resistors. Because I had 2 valve coils, I soldered LEDs with 2 different shapes

  • Shape 1 with 4 LEDs, soldered to 1.7W valve coil.

  • Shape 2 with 12 LEDs, arranged in cylindrical form and soldered to 3.0W valve coil.

Finally, I glued all valve coil terminals. DONE!

  • Shape 1

  • Shape 2


The voltage measured at terminals of valve coil by multimeter is about 24VAC. In industrial field, some indicator light module are used at 24VAC / VDC and these module normally include: LEDs plus some resistors, for example:

This lamp indication module includes: LEDs and 3pcs x Resistor 700 ohm and they are connected together in series.

With 1.5W valve coil (connecting to 4 LEDs), the LEDs will illuminate if the valve coil is placed nearby toothbrush charger.

Step 4: FINISH

Thank for your watching and I hope you like it!!!

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