... any electronics geeks in the house? I need a simple circuit, to generate a biased sine wave, or dampened square wave, at low frequencies, sub 1Hz, pref in the range of 0.1Hz to 1Hz, to drive an LED and make it slowly rise and fall in brightness.. Most circuits deal with higher frequencies, and it's been an age since I did any electronics, and although I recall using a capacitor and resistor to set the frequencies, can't remember what the formula was.