Torben
Well-Known Member
Hi all,
I've breadboarded a simple electret preamp based on the commonly-seen schematic presented at **broken link removed**, and after adding a resistor divider to drive the electret mic, it appears to work quite nicely in initial tests. (Not going for ultra quality off the bat here; just looking for design technique help).
I've been laying out the PCB in eagle for it, and I just have a couple of questions about ground and line lengths:
1) Would I likely benefit from running traces from each ground point to a single point at/near the power supply 0V input (i.e. star ground using traces)? This is as opposed to either using a ground pour on the bottom (solder-side) layer or using a ground plane on the top layer.
2) The electret element (ye olde radio shack cheapo) has a FET built in, right? Will this suffice as a line driver so I can mount the electret at the end of, say, a 30-60 cm line? Or would I need to further buffer it?
Pointers to reading are as welcome as flat-out responses. I don't mind terribly just testing all this, but I would like to avoid etching the boards just to find out...and the theory always helps understand the "why"s instead of just the "what"s.
Thanks all!
Torben
I've breadboarded a simple electret preamp based on the commonly-seen schematic presented at **broken link removed**, and after adding a resistor divider to drive the electret mic, it appears to work quite nicely in initial tests. (Not going for ultra quality off the bat here; just looking for design technique help).
I've been laying out the PCB in eagle for it, and I just have a couple of questions about ground and line lengths:
1) Would I likely benefit from running traces from each ground point to a single point at/near the power supply 0V input (i.e. star ground using traces)? This is as opposed to either using a ground pour on the bottom (solder-side) layer or using a ground plane on the top layer.
2) The electret element (ye olde radio shack cheapo) has a FET built in, right? Will this suffice as a line driver so I can mount the electret at the end of, say, a 30-60 cm line? Or would I need to further buffer it?
Pointers to reading are as welcome as flat-out responses. I don't mind terribly just testing all this, but I would like to avoid etching the boards just to find out...and the theory always helps understand the "why"s instead of just the "what"s.
Thanks all!
Torben