Inspired by this instructable and having some spare room on a PCB order I decided to make a solar powered LED blinky in the shape of a face

Solar power is provided by the 6 BPW34 photodiodes which charges up the super capacitor C2, since this supercap has an input impedance of around 300 Ohms  this is decoupled by C3 to power the ADCMP371.

The ADCMP371 is configured as an Astable oscillator and AC couples into the LED’s D7 and D8.

It takes most of the day charge and lasts about 2 hours blinking the LED’s, Layout is on a 2 layer circular PCB below. The 4 pads in the centre are intended to be sown onto things.

The Bill of materials for this project is below

QTY              PART-REFS           VALUE              

---                  ---------                     -----              

Resistors

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4                    R1-R4                       1M                 

 

Capacitors

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1                    C2                              1F                  

1                    C3                              47uF               

1                    C4                              10uF               

1                    C5                              0.33uF             

 

Integrated Circuits

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1                    U1                              ADCMP371           

 

Diodes

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5                   D1-D6                         BPW34              

2                   D7,D8                         DIODE-LED