Mauryc:
@HellasT, are the values of the capacitors coming from experience?
Yes but also yu can find diagrams that use the exact same values.
Mauryc:
@HellasT, this may be standard, but if that would be 7809, would the values be different? I suppose that other devices drawing power from that 12V will influence this.
For an 7809 it would be the same. Also i dont think that other devices powered by the 12V will affect the 7805.