[Kevin Darrah] wanted to make a simple 3.3V regulator without using an integrated circuit. He wound up using two common NPN transistors and 4 1K resistors. The circuit isn’t going to beat out a ...

(Although we think he really made it for the fun of making it.) The circuit is centered around a TL431 programmable shunt regulator, which is an awesome and underrated chip in its own right.

The circuit has a shunt regulator, internal voltage and bias current generators, built-in power-on-reset and oscillator. The core is easily retargeted to any other CMOS technology with R-poly devices.