[sdiy] WP LM3900 VCF

[Paul Perry]

It's a swindle, really!
I once spent ages tryng to see how a Norton amp 
could be made into a filter <blush>
The LM3900 is just used as a current-voltage converter, it's 
matched pairs of 390s's that is doing the actual VCF
so far as I can see, looking at this schematic
(thanks again to Don Tillman)
http://www.till.com/arptech/pdf/4072.pdf

paul perry (up past his bedtime in Melbourne Australia)