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: 
You'd probably want a [astable multivibrator](https://en.wikipedia.org/wiki/Multivibrator). Here's one easily constructed with discrete components:

[![Transistor Multivibrator.svg](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6a/Transistor_Multivibrator.svg/1200px-Transistor_Multivibrator.svg.png)](https://commons.wikimedia.org/wiki/File:Transistor_Multivibrator.svg#/media/File:Transistor_Multivibrator.svg)  
By jjbeard - Own drawings, made in Inkscape 0.43, Public Domain, <https://commons.wikimedia.org/w/index.php?curid=873818>
It is possible to create a light flasher using just a heating element and a bimetallic strip. It's likely to be horribly inefficient, but it can be made to work.

And there's not even a transistor needed.

There's an example here [Evil Mad Scientist](http://www.evilmadscientist.com/2008/easy-high-power-led-blinking-circuit/) using a blinking incandescent lamp, of the sort sometimes used in Christmas decorations.

![schematic](https://i.stack.imgur.com/B5lLL.png)

[simulate this circuit](/plugins/schematics?image=http%3a%2f%2fi.stack.imgur.com%2fB5lLL.png) – Schematic created using [CircuitLab](https://www.circuitlab.com/)