quick noob question

[slayer665]

I'm building a tubescreamer and in some schematics i see a 100uf cap and a diode from 9v to ground like this---> http://www.generalguitargadgets.com/diagrams/ts-808.jpg and sometimes it's not there... like this ---> http://www.muzique.com/schem/ts808.gif . Is that diode and cap needed?

[The Tone God]

The diode is polarity protection and the cap is extra power supply filtering. Can you live without it ? Probably but if you ever are in a situation where either would be useful it would be nice have them there already. I say put them just in case.

Andrew