Hi Joseph
Following is a link to a site that has a simple B+ power supply schematic, just scroll down and you will see it.
https://www.antiqueradio.org/bsupply.htm
I use an ARBEIII Universal Battery Eliminator for my battery radios which works really great. It is really easy to use and simple to hook up. There is also a 81 page set of connection diagrams for the early battery radios. Following is the site for the eliminator.
https://www.arbeiii.com/
Following is the link for the 81 page connections diagrams.
http://arbeiii.com/ARBE-III%20Compiled%20Wiring%20Diagrams.pdf
Hope this helps you.
Bruce