Question: I want to make a blinking light for my transformer when I charge anything with it. But as an educational exercise, I don't want to use any kind of IC. Can anyone help me?

Answer: 
Here you go. But a 555 would be easier, require a smaller capacitor and it might be easier to explain how it works. 

![schematic](https://i.stack.imgur.com/bi5TW.png)

[simulate this circuit](/plugins/schematics?image=http%3a%2f%2fi.stack.imgur.com%2fbi5TW.png) – Schematic created using [CircuitLab](https://www.circuitlab.com/)
How about an old-fashioned UJT?

[![enter image description here](https://i.stack.imgur.com/kqkLT.png)](https://i.stack.imgur.com/kqkLT.png)