(for the curious, schematics and some circuit analysis in this thread.)
(btw, the original design is from the ASM-1 “single PCB modular” by Gene Stopp (archived ASM-1 home page). Rönnberg redraw the schematics and made a stripboard layout, but the original is by Stopp, based on earlier work by Bernie Hutchins of Electronotes fame and opamp legend Walt Jung (who I’m pretty sure is behind the supply voltage trick that puzzled us in the other thread.))