To say Craig Anderton’s body of work is vast is probably an understatement. But within that body are several DIY classics, and this tremolo is no exception. This is a modified/updated version, specifically in the power section with a +/- 9v charge pump. The vactrol in the original is VTL5C1, but some combination of home rolled LDR/LED combo will probably work (you’ll just have to experiment a bit). Schematic here. It’ll be snug, but it should fit in a 1590B.
