Ambient Light Powered LED Flasher

This LED flasher circuit is optimized to run from the ambient light present in your room and no other power source. A small photovoltaic cell converts the light to electricity and that weak current charges a 1000uF capacitor. After a time period of around 1.5 seconds, the stored energy is discharged through an LED.

FV cell: should deliver at least 2.5v (no load open circuit) and 0.5mA short circuit current (under room lighting)

Incandescent / halogen lighting is the most efficient for F.V.cells (after daylight) and fluorescent is the least.

Q1-Q2: BC549 npn transistors

Q3: 2N7000 N-channel mosfet. You may have to select it for lowest gate threshold voltage or use a low threshold BSH103

LED: use a high efficiency red LED . (red LEDs have the lowest forward voltage (Vf) )