PCB layout tips

[JacksonRR]

Anyone have any for a preamp section? I'm gonna have to do single layer. Is it ok to run short leads to my 12ax7 pins and control pots?

[Jazz P Bass]

I do not see where the "short leads" enter into it.
I would recommend that you keep signal away from power traces.
Dito for the heaters.
Power & heaters traces must be sized according to current requirements.
Good luck with the single sided.
There is not any through hole plating to mechanically stablize the pins.

[defaced]

I do not see where the "short leads" enter into it.

Seems to me you don't want to emit or receive any more noise than you have to - this of course balances with spreading things out to minimize crosstalk. I always think of a PCB as a glorified PTP/turret layout and the same "lead dress" rules apply to the copper as they do to the wires.

Patience. This goes for any PCB though. You will suck at it the first 10 times. I look back at my old designs and go "WTF?". Keep at it. You will get better at it.

The stomp box guys don't follow some of these rules, but:
Use the tools your software has to check the schematic and the layout for problems
avoid right angles in your copper (this is for etchability so I've read)
put things close to where they belong
keep traces short when you can, but spread parts out when you can to minimize cross talk and noise
minimize parallel traces for long distance
watch your grounding and power layouts - keep them logical and follow good grounding practicies. I have not tried a ground pour for grounding, and for a multi stage circuit, would think is could cause problems.
decouple the power supply near where you'll be using that power (power supply filter caps)
look at other PCBs that are quiet and stable and see what they did
know what signal is in what wire and place them accordingly to minimize noise
protoype, and expect to do it more than once

Read through the Eagle rules on SparkFun Electronics. Good stuff there. If you're using Eagle, download their DCR and their libraries. Same goes for gaussmarkov's Eagle libraries.

Those are some of the guidelines I used for my first preamp layout - this after having done a few turret layouts and seeing what works for me. I have not had the opportunity to prototype the PCB yet. It'll be interesting though. I'm wondering how stable it'll be because it's a very cramped layout and a high gain circuit. It's also double layer, and well, that complicates the prototyping process a bit.

[JacksonRR]

Thanks guys. I was using express pcb, but I will check out Eagle. I did open two amps yesterday for "advice." The power and heater tracings are almost a quarter inch. I did notice that off the bat. So you guys feel a 2 layer design is best?

Short leads... Well the turret board construction has tons of wires coming off. I've never been a guy that likes soldering pots directly to the board. I was wondering, if it helps the circuit, can I keep my methods or do I have to man up? I see a lot of parallel traces going to the pots in both my amps as I type.

[defaced]

The design will dictate what you have to do. If you can do a single layer board and its stable and quiet, then it's a fine design. Same goes with off board mounted pots (but I don't think you'll have a problem here provided you use shielded wire where needed).

If you use Express PCB, you pay Express PCB prices for your boards. And your design can only be made at Express PCB. If you use Eagle (or another program (Protel, KiCAD, etc) that can make Gerber files), you can shop. And there are some great deals out there.

[JacksonRR]

I was gonna etch my own. I have a good selection of pcbs, single and dual at a Fry's electronics down the street. Etching solution all that junk.

[R ski]

One word of wisdom about circuit card layout, use plenty of ground trace, preferably surrounding the contents as much a possible, this helps with combating those annoying hums and other squeals that may happen. Then wiring practices from the card to devices can add to that annoyance as well. Good luck