I have a mission to build a dummy load to make a PSU test and found some schematics with a positive load. It worked like a charm.

Electronic load, Problem turning MOSFET on

But there is no information about how to drain from PSU negative side I've searched all internet and no answers.

Please, anyone could help?

EDIT: Hi @bobflux . Sorry for the delay. I´ve build this one an it worked. Thank you!