Need a quick diode explanation

[served]

Hi.

I was wondering if anyone could lighten me.
I wonder why is it necessary to drive the voltage through diode in +V (9V)

I have seen two different schemes.
One is Diode between the + and -
Other: +9V flows through the diode.

Diode between + and - is polarity protection, but what is the purpose of the other scheme?

[.Mike]

Geofex: Advanced Power Switching and Polarity Protection for Effects

The third through fifth paragraphs explain both of the diode polarity protection schemes that you mention.

Mike

[served]

Thank you very much!

I was thinking the same thing, now I know that it actually is so.
So series diode is no go for me.
Thanks!