This module uses G6L-1P relays - and its design is inspired by Everlanders Automation projects (video) (Project Home page), where a Wemos D1 mini wireless remote control option is added to the MaxxFan in the Everlander rig.
In the Everlander project G6L-1P relays are used, so this PCB also uses G6L-1P relays.
Project Status: PCB design verify (rev.A1 - 2023 May 16)
Here are some screen shots:
Notes about un-knowns:
Use the PCB viewer if you would like to see/test the entire copper path as it switches sides and/or connects to several solder points.
Chips:
Miniature relay G6L-1P
Datasheet: omron_g6l-1-relay.pdf
ULN2803a Darlington Transistor Array
(Top View)
Datasheet: uln2803a.pdf