To ground or not to ground...(Rebote 2.5)

[monkeyman]

Hey guys, I have a quick question.

I'm building the Rebote 2.5 from Tonepad on perfboard, http://www.tonepad.com/getFile.asp?id=98 , and at first I was just looking at the schematic. Pins 4 and 6 of the PT2399 both end in a funny little arrow, which is not quite a ground symbol. I assumed that the symbols were just a shorthand to show that the two pins ultimately connected together, but looking at the PCB layout I'm not so sure. On the PCB pins 4 and 6 both connect to ground (or so it looks). So which is it? Any ideas?

Thanks in advance!!
Bo

[.Mike]

I think that the empty triangle ground symbol is being used as  "digital ground."

http://digital.ni.com/public.nsf/allkb/11BE00780D41622686256BE5006F04CF

From what I gather, digital grounds should all be connected together, and then the digital ground should be tied to the circuit ground at one point. I'm sure someone will correct me if I'm wrong.

Mike

[Auke Haarsma]

You are correct .Mike.

Often you will see Analog ground and Digital ground connected at one point via a small resistor (10 Ohm). This is to keep the digital 'noise' out of the analog ground and thus the signal path.

[monkeyman]

Thanks guys!

That's just what I needed to know.

Bo