simple LFO question

[Byron G. Jacquot]

>| > The Hypertriangular lfo design by Anderton was based
>| > on a Curtis CEM 3340 VCO chip -- I have the schematics;
>| > could scan them & send them to you, but you'd still have
>| > to get hold of one of those hard-to-find chips.
>| 
>| 3340s are currently available at www.synthtech.com.  Paul has plenty at the
>| moment.
>+------
>Oh piffle... I'll just yank a few out of my jp-6 if I need some. 

That's the spirit!  <G>

Actually, if you're looking for a reasonable approximation of a
"hyper-triangle," there are some little single ICs that serve as
multi-waveform generators.  There's the 566 (not to be confused with the
556, a dual 555 package), and the Exar deal with a number something like
8038, IIRC.

One of them makes a reasonable sine wave without much fuss.  You full-wave
rectify the sine and use the negative output for an approximate
hypertriangle...moving quickly at the tops, but more slowly at the bottoms.

You might want to follow it with something for scaling & level shifting.

If you aren't so picky about waveforms, and plain triangle and square might
do the trick, you could use one of the above chips, or use the usual LFO
design, such as is in the ASM1, or
here:http://www.xavax.com/efm/pdf/lfo1.pdf.  The Blacet mini LFO is a
variation on that theme, on a circuitboard about 1" square.

Byron Jacquot