Rolling Your Own Neural Network

Seen several of these tutorials now interlaced with all concepts, math and code.  This one seems nicely done.   When we first played with these in the 80s we wrote our own from bottom up code, now you can roll your own with libraries quite easily.

Build an Artificial Neural Network(ANN) from scratch: Part-1
Towards Data Science by Nagesh Singh Chauhan 

This article focused on building an Artificial Neural Network using numpy python library. ...