[sdiy] Real slow LFO ICs?

[ASSI]

On Tuesday 28 October 2003 00:06, Paul Perry wrote:
> Depending what you want to do with the LFO.... a very slowly stepped
> LFO is very noticeable indeed. This is just about the only thing I
> wouldn't want to do with a micro, but I'd like to hear more opinions.

If you can constrain the upper frequency for the LFO suitably, you can 
achieve almost arbitrary resolution on the amplitude (the tradeoff is 
indeed on SNR, not resolution). The advantage is that you get very 
precise and consistent timing/frequency over a wide range, which is 
otherwise hard to achieve in the sub-Hz range.

If that is not a goal, a simple triangle core, perhaps followed by a 
sine former, does the job well. I've built one out of a 555 timer by 
replacing the charging resistors with current sources some years ago. I 
don't think it was very repeatable or particularly precise, but it did 
a reasonable triangle down to the mHz range.


Achim.

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