[sdiy] Really Low, LFO

[Kyle Stephens]

Can anyone point me to some reading material on infrasonic oscillator design? I want to build a really low, low LFO, with a period of around half an hour (yes, _that_ slow!).

As HF designs have their share of issues that get worse in that spectrum, infrasonic has its problems too I would imagine - I just don't know what exactly they might be.

For my app, accuracy isn't as important as precision/repeatability, though if both are possible then both are welcome.

Closest I've found so far is this:

http://tinyurl.com/yf9wzp3

I reckon I can tailor it if I make the integrator cap several decades larger, to shift that 0.1Hz to 100KHz range several decimal places downward.

I've a copy of AD's Nonlinear Circuits Handbook, which has some material on the topic, though nothing too specific on freqs beneath 1 Hz (half an hour is ~ 0.0001 Hz).

I spoke to Prof. Lanterman about this a while back, and he recommended a microcontroller based solution, and while that's something I want to break into, it's a whole 'nother can of worms too. If this can be done in analog, it'd be a cool achievement and an enrichment exercise if nothing else... :]



_Kyle (so slow it Herz?)