LM2596 regulator example
This is quite a common power supply, a lot of the simple breadboard power supplies available on Ebay are based on this kind of design.
Many of the parts are common and this can be quite easily designed into a board or you can make a stripboard version. The spec is underneath in the link section, this example should be able to supply about 1a over a voltage range of 3 to 12v.
Qty Value Device Package Parts Description 1 100nf CAPPTH CAP-PTH-SMALL C3 Capacitor 1 10k POTENTIOMETER 0603-ARV R1 2 220uf CAP_POLPTH1 CPOL-RADIAL-100UF-25V C1, C2 Capacitor Polarized 1 330r RESISTORPTH-1/4W AXIAL-0.4 R2 Resistor 1 330uh INDUCTORAXIAL-0.6 AXIAL-0.6 L1 Inductors 1 LM2596T LM2596T T05D IC1 SIMPLE SWITCHER® Power Converter 150 kHz 3A Step-Down Voltage Regulator 1 SS54 DIODE-ZENERPTH DIODE-ZENER U$1 Zener Diode