+V plane and GND plane on same board?

[pappasmurfsharem]

I believe I saw in the JMK eagle tutorials that he uses a 9V (voltage source) pour on the Top or Bottom layer and the reasonably de facto Ground pour on the opposite layer.

What are your guys' thoughts on this? It helps make routing easier, but are there downsides (I'm sure there are).

Any particular effects types where this can be problematic?


*edit*
modified title

[mth5044]

Check out this thread: http://www.diystompboxes.com/smfforum/index.php?topic=90573.0

May answer the ground pour portion of your question.

[pappasmurfsharem]

Check out this thread: http://www.diystompboxes.com/smfforum/index.php?topic=90573.0

May answer the ground pour portion of your question.

Thanks for that. I'm relatively happy with the idea of the ground pour for most things.

My question was more towards using them in conjunction with eachother one layer ground one layer voltage source.

[pappasmurfsharem]

Bump

[armdnrdy]

This may answer a few questions:

http://www.alternatezone.com/electronics/files/PCBDesignTutorialRevA.pdf

[R.G.]

For effects with only audio in them (that is, no digital logic that's continuously clocked, - the PT2399 being an example) ground planes may be somewhere between harmless if not very useful to detrimental if done poorly. For high frequency RF and fast-edged logic, ground and power planes may be the only way to get it to work.

At DC, ground planes are in the way. Better to do full star power and ground. The higher the frequency, the higher the inductance of isolated wires, and the more the need for planes. However, at quite high frequencies, even this is not enough, and planes are simply a way to lower the DC resistance by using all available space for copper. The actual low-inductance power resources are the low-ESR caps right at the chips or power parts.

Using a ground plane and thinking this is a panacea may deflect your attention from the three types of "ground" : shield ground, reference ground, and "sewer" ground, the return of used eletricity back to the power supply. At high frequencies, field effects forces return currents to flow in the plane under the signal wire. The return currents all stay right with the signal traces for what they return - unless you go splitting the plane up and making it odd shapes. If you do things this fast, you'd better use multilayer boards to make real planes, not pour copper around the unused area. If the frequencies are lower, forcing the return/sewer ground current to flow where you want it by star grounding is as good or better than simply putting all the unused space in copper and hoping.

To the original poster's question: You *can* make a +V and a ground "plane" on the same board by pouring different areas, but it offers a simplistic look that belies its performance. It may be pretty, but often is no better than critically routing returns and references depending on the currents flowing in the traces. To do a proper job of +V and ground planes, you need at least a three layer board.

... that's my opinion.