LPB w/ LED...

[scott_v]

Ok this is sorta a newbie question i had taken a long break from making pedals and it appears that i may have forgotten some stuff! so here are a two questions...

1) On generalguitargadgets.com for the schematic on the Electro-Harmonix LPB it shows a diode (1N914) to be used between the + 9V and R1 (this is also where the resisitor connect to the LED is connected).  Is the purpose of this diode to prevent the circuit from being fried from accidental polarity mismatch of the power?
I had already built this pedal previously, and i'm pretty sure i didn't use a diode here (i will have to relook at the circuit i built) and the pedal functions normally, and i only wired it for use of a battery...

2) There is an electrolytic capoff (100uF) of R3 to ground, its not used in the original schematics for this circuit... i'm assuming this is to help rid of any RF noise that may occur? or

the schematic is here:
http://www.generalguitargadgets.com/pdf/ggg_cb1_sc.pdf

[maarten]

Hello Scott,
you are right, the diode is there for polarity protection; so if you are sure you are not going to make any mistakes with this, you could do without it.
The cap is the typical supply cap; in some circuits you will find you can do without it, but usually it is better to have it there. Some schematics will not show these types of parts, they are taken for granted sometimes. So it could be that if you open the original pedal, this cap is present - I don't know if this is the case here.

Maarten