"SuperCap" Solar Candle
The attiny13 based solar candle has been a success - based on a "joule thief" modified circuit that runs a micro-controller to ramp a couple of LEDs up and down to simulate a night time candle.
The attiny13 runs at 128kHz, the code is written in assembly to minimise overhead and the hardware is optimised to reduce power requirements.
Then along comes a couple of weird ideas out of left field!
1. Use the Padauk PFS154 or the PMS150C microcontrollers, both of which have an extra PWM channel to give three ramping channels of candley goodness vs two (for more authentic fakery).
2. Run the Padauks at 53kHz to further reduce power.
3. Craziest - replace reliable affordable NiMH rechargeable batteries with unknown super capacitors! Huh?
Stage One and Three are done, but even with 30F supercaps I'm not currently get more than a few hours of candle imitation. I've yet to deploy the 5050 LEDs which I normally use to reduce power - so there's a possible saving.
I have also yet to spend any quality time cranking the Padauk's clock to ILRC AND successfully maintaining good PWM.
I believe that I am chasing a foolish dream at this stage - but I want to eliminate all possible barriers to the concept of a candle that in 2500 years time (based on 1 million charge/discharge cycles) is still providing a reassuring lovely glow in the wee hours.
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