VW Electrics Smooth 12v/5v supply

These days, we run laptops and other items that need a smoother or even reduced supply compared to the nominal 12.5V supply, particularly if the engine is running when the voltage can reach 14v. The dash clocks use a fixed 10v supply for part of the circuit and this is maintained by a voltage regulator fixed to the back of the clocks.

Relatively cheap, voltage regulators have three legs and come in various sizes as follows:

LM7805 (5v) LM7809 (9v) LM7812 (12v)

With the addition of a few capacitors to further smooth out the supply, you can build a simple and effective power source at one or more voltage levels.

Heres a summary of the circuit: