Similiar to a 7805, but more efficient. Output 3.3 volts.
My attempt was to make a three pin module which could be soldered into the place of a 78xx type of voltage regulator, making use of the switchmode control chips in order to implement a more efficient solution.
This one makes use of the TC105333 integrated circuit
manufactured by Microchip. This contains all the components of the power supply except the switching transistor, freewheeling diode and inductor. The TC105503 can be used for 5 volts output, thus creating an efficient 7805 replacement which needs no heatsink.
The switching device is a TPS1101 PMOS Transistor
manufactured by Texas Instruments.
The freewheeling (schottky) diode was extracted from an old hard drive board. The inductor has a resistance of about 1.8 ohms and was extracted from an ancient VCR board.
With no load, and an input supply of 6 volts, this circuit draws about 17 microamperes. With a resistor of 33 ohms connected (load 100 mA) the current is about 63 milliamperes. This computes to an efficiency of around 87%.