Plz Critique My Layout

[Stickman393]

A'ite homies. I'm giving PCB layout a shot. This is my first, complete board layout.

@Chuck D. Bones posted these in the Boneyard: it's his PNP Servo Fuzz Face with his Simple Relay Bypass. Because good artists borrow, great artists steal.

ANYWHO...fuckin, brutalize me. Let me know what I did wrong. I NEED TO LEARN.

I haven't done the ground pours yet, or stupid doodles...this is just a basic layout.

 

[CR0SSBL4DE]

The relay coil is connected directly to V+. If you want it to switch, you need to use the output signal from the 555.
And check the 555 connections, some stuff is connected incorrectly. Compare it against the standard bistable 555 circuit.

 

[Stickman393]

Huh. Correct. Whoops. Had adjusted the schematic a bit to account for different footprints. Didn't get everything back to normal.

Lemme fix that...

 

[Stickman393]

A'ite. got it fixed. It reflects chuck's simple relay bypass schematic now.

 

[rwl]

I'm by no means an expert, but here's some changes I'd make:

1. Orient all the electrolytic caps the same direction. Makes verification easier and looks tidier. In this case it's natural to put negative down since two are already oriented that way and the other two won't be worse.
2. The lower left transistor + R2/C10/R4 can be rotated as a unit and I think it would end up being tidier. Then you'd have the two transistors facing the same way, also useful for verification and looks tidier. You could then also pull in R17/R16 closer to the IC.
3. I'd move the upper electrolytic cap to be on the blue trace you've already laid out.
4. I believe you can line up R11/R13/C7/R8/R10 in a row, esp if you move the lower right capacitor down. A few would have to be flipped around.
5. What width are the traces? They don't look right to me at a glance, there seem to be too many thick traces (more than I'd expect from the typical number of power traces) and the skinny traces are really skinny.
6. Maybe it's just my eyes but the resistors look small. I'd expect the resistors to have pads with the same spacing as the DIP8 IC. This looks closer to a 1/8W than 1/4W? And the Diodes look huge by comparison. In my layouts the diodes are the same pad spacing as the resistors.
7. It might be too late for you at this stage, but I'd also consider always orienting the ICs with pin 1 in the upper left. I always seem to mis-socket ICs and a consistent orientation makes it easier to catch.
8. I'd consider rotating the 8-pin component (relay?) at the top. That would give some more space and I think you could line up R1/C4/R5/C5 with a vertical orientation. Pin 1 and 8 would also then have a more natural orientation, though it's hard for me to visualize the other pins. Pin3 would be an obnoxious route with that rotation but I think the rest would look better.

Here's a crude visualization of some of the above with magenta as new routes or rotations, and white as moved pieces:

 

[Stickman393]

^ love it!

Thanks! Gonna pore through that list and implement some changes.

1. What width are the traces? They don't look right to me at a glance, there seem to be too many thick traces (more than I'd expect from the typical number of power traces) and the skinny traces are really skinny.

10mils and 24 mils. I wasn't entirely sure where I needed to "end" the power rails. What's good practice here? Keep the rails wider until you get to the first load, then reduce trace width?

1. Maybe it's just my eyes but the resistors look small. I'd expect the resistors to have pads with the same spacing as the DIP8 IC. This looks closer to a 1/8W than 1/4W? And the Diodes look huge by comparison. In my layouts the diodes are the same pad spacing as the resistors.

I believe you're correct! Thanks, I had missed that bit.

*Monday edit* yup... those lil footprints totally fucked up my layout. Had to start from scratch.

Got a better layout now. Reduced everything on the power trace to 0.5mm, increased signal traces to 0.3mm.

Exporting from kicad is a PITA. Right now I'm printing to PDF, then importing to inkscape and exporting as a PNG.

woof.