LED message system on a Strida folding bicycle wheel using PIC12F675

I've designed a simple solar lighting circuit. It has got a small microcontroller a very simple charge controller and a voltage multiplier. The part at the lower left of the schematic is the voltage multiplier. It transforms the voltage generated by the 1.2V nimh cell to almost 4V which is enough for the ultrabright LEDs to run properly. The PIC12F675 microcontroller can work with voltages 2-6V so it is not problematic.

some of the solar garden lights have an internal voltage doubler too. Mine has got one too. But I've sticked to the circuit schematic. If you find one in your solar light, then you can use it instead of the one in the schematic. All you have to do is open circuit the LDR (light sensor, if there is any). I've did that to the doubler I've took from the disassembled light and put it a side for further use.

Next thing is to assemble the circuitry on multi holed prototype board. This will require some soldering and electronics assembly skills. I'm sure there are many instructables around this subject. You may take a look at them so I'm not mentioning about the assembly here. The photos are of the first light I've tried. It had 10 ordinary LEDs. I've designed a resistor network method for driving 10 leds with a controller having only 5 output pins. The method increased power consumption so I've gave up that. Later I'll make a second version with a bigger controller and 10 or more LEDs. This version of the circuit has got 5 LEDs.

The circuit is secured to the air valve of the tire. I've used a metal valve cap and used hot silicone to glue circuit to the cap.

The proteus simulation file (demo is available on labcenter.co.uk ) is also included for the ones who want to see the circuit working.