Solar-powered flashing LED heart pendant

for Mouser and MacroFAB Blink An LED competition

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Whats it is make special MacroFab Design Contest: Blink an LED Sponsored by Mouser Electronics ???

- wearable
- innovative
- effective
- easy replicable
- with good coating survive doomsday
- flash indoor
- indoor voltage from solar cells is only 1V and 1uA, it is harvesting masterpiece

Led flasher work as charge pump, multiply input voltage twice to get 2V pulses

Advantages compared to other designs.

  • discrete components, no special QFN chip (two standard transistors, 5 resistors and 3 capacitors)
  • based on charge pump design
  • work indoor, no direct sunlight required !!!!
  • startup current is less than 1uA, it is much lower than on commercial harvesting IC or designs

Why again BPW34 aka solar cell?

  • PLASTIC, harder to break
  • easy to buy, it is smallest commercially available solar cells
  • there is no way to get small non Chinese solar panel
  • IXYS solar bit are discontinued
  • Panasonic amorton are made from glass and is not easy to buy

As you can see on video, led flashing in room light.

I created all on breadboard and about month experimentally adjust components values to get best performance.

Board image

Bill of materials with Mouser links to each component:


  • 1 × MMBT2222ALT1G Discrete Semiconductors / Transistors, MOSFETs, FETs, IGBTs
  • 1 × MMBT2907ALT1G Discrete Semiconductors / Transistors, MOSFETs, FETs, IGBTs
  • 1 × any 3528 RED LED
  • 2 × 0603 resistor 10M
  • 2 × 0603 resistor 22K

View all 9 components

  • 1
    Just assembly and enjoy

    It is crazy simple device, no programming, no micro-controllers, old fashion passive design,  just solder components and enjoy :D

View all instructions

Enjoy this project?



Kaspar Emanuel wrote 01/31/2019 at 15:09 point

These are really nice, is there a schematic so I can better understand the circuit?

  Are you sure? yes | no

phuzybuny wrote 11/28/2022 at 04:38 point

OP has a similar project with a schematic and image of a test schematic. However, the two schematics are slightly different (e.g., resistor values, placement, etc.).

  Are you sure? yes | no

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