Software function generator & SMD problem

[eeka chu]

Hi,

These are kind of simple questions, but your definitly the guys who'll know!

This will sound kind of strange but...

Is there any freeware or software that I could use to waveforms from my soundcard? In the end, I would like to be able to produce these waveforms and then export them as MP3's.

I could really do with being able to pan between two stereo channels, control amplitude, frequency, distortion, distortion type and such.

I've tried NCH tone generator, but it's waaay too basic - as I can only really pick a basic waveform and frequency.

A software function generator I guess I mean.

Secondly, I was reading through one of NSC's PDF's for good switchmode supply layout and noticed something odd.

Around the pads for the SMD components, there was a lighter grey line, probably for the tolerances, but then a white seperator line to show a break in the tracks around the pad.

The solid white line breaks at four points around the pad to allow it to connect to it's surrounding plane - it almost looks like a crosshair with the pad in the middle and four conducting lines going out, one from each side.

It is used throughout the schematic, on every pad. What is confusing about it, is that it is used to connect some very high power components, like the inductor, to their planes. If these components require the maximum amount of conductance to their planes, why would you form such a crosshair like connection?

If you're not sure about what I'm describing, NSC's application note AN-1149 has an example of it in.

[andrei]

The solid white line breaks at four points around the pad to allow it to connect to it's surrounding plane - it almost looks like a crosshair with the pad in the middle and four conducting lines going out, one from each side.

These things are called thermals. They are used both with SMT and trough-hole components to facilitate soldering. As the solid copper plane has high heat conductance, without them the heat is transferred away faster than the soldering iron could supply it.