has got to be the simplest project of anything I've made so far.
It uses a PIC to simulate the flickering of a candle entirely in software.
The brightness of the lamp is controlled by doing PWM (pulse width modulation)
of the power to the lamp. A random number generator controls the
seen in the schematic, only 3 pins are used on the PIC12F675. PWM
is generated on GP5 to drive a small transistor. This gives enough
current to run a 6.3 volt lamp.
Since the lamp
is basically powered by an average of 2 or 3 volts, it tends to be more
'yellow' in color. This helps in the candle flame effect.
This device is installed in a plastic water jar decorated with transparent
colord graphics. Most guests here simply assume its a real candle
in the bottle. A few get curious and look down to see the circuit
For those who wish to duplicate this project, the Source
and Object code is available.