Designed the PCB we using EasyEDA’s online PCB design software. EasyEDA is a full suite schematic and PCB design software, PCB manufacturing service that’s free to use and offers custom PCB manufacturing service. To edit the layout, change PCB component footprints click on the image below:

The pcb component labels match on the PCB labels in the schematic--Custom PCB

PCB DESIGN TIPS

There are four basic principles I took into account when designing this PCB:

PCB design Current flowing through a conductor creates a magnetic field that can generate a current in a parallel conductor.

Current flowing in a conductive loop creates a magnetic field, and a magnetic field generates a current in a conductive loop. The magnitude of the current is proportional to the area inside the loop

Inductance inhibits the flow of current. Long, thin traces have more inductance than short, thick traces

A capacitor in series with an inductor creates a resonant circuit.

PCB design The traces leading to the non-inverting input and feedback loop have been routed far away from the power supply and audio output traces to prevent high currents generating currents in low current traces. If routing a low current trace near a high current trace is unavoidable, run them at 90° angles, but never parallel. If you put the terminals for the high and low current circuits on opposite sides of the PCB, it will be easier to route them far away from each other.

Any space between traces of the same circuit will create a conductive loop that’s susceptible to receiving or transmitting magnetic fields. To avoid this, I’ve routed the positive and negative power supply traces close to each other, and used ground planes on the bottom of the PCB. When traces are routed over a ground plane, the width of the loop is reduced to the thickness of the PCB.

Since the power ground and signal ground need to be kept separate, the bottom side of the PCB has two ground planes that are not connected electrically. One ground plane carries the power ground, and the other ground plane carries the signal ground. On the top side of the PCB, the power supply traces, output, and Zobel network are routed over the power ground plane. The input and feedback loop traces are routed over the signal ground plane.

PCB design A capacitor in series with an inductor creates a resonant circuit, which can cause oscillation. Inductance also inhibits the flow of current. To reduce the effects of inductance, it’s best to keep all traces as short as possible. This is especially important for the power supply decoupling capacitors, the feedback loop, and the Zobel network. They’ve all been placed as close as possible to the chip’s pins to shorten the trace length.