I am not sure if you can still get them, but back when SCR/Triacs were first released, G.E. published some small books on using Thyristors.
One was entitled Experimenters Circuit Manual Projects for Hobyists,Engineers.
It gave theory and practical circuits using Low Voltage AC for Triacs and SCR's, some example titles were Model R.R. controller, Electronic Dice, Touch switch etc, etc.
Provides a safe environment for experimenting.
You may be able to get the book from such as AbeBooks clearing house etc.
I see there is one with almost the same title and content but 1990's for $1.00 https://www.abebooks.com/servlet/BookDetailsPL?bi=14871593008&searchurl=kn=circuit+manual&sortby=17&cm_sp=snippet-_-srp2-_-title5
Max.