How to debug your circuits

Clarus Goldsmith, June 2024

Create it on a breadboard first

As the title says, create your PCB circuit on a breadboard first. That way it's easy to swap components in and out and check connections. If you need to include surface-mount (SMD) components in your circuits, use a breakout board (detailed in the next section).

Breakout boards are your friends

When you need to check how a particular SMD component works, or want to include it in a breadboard setup, you can use a breakout board. Breakout boards are just super simple PCBs that wire the pins of an SMD component to terminals for header pins. They come in all sorts of form factors for all common package sizes (MSOP, SOIC, etc.)

Example of a breakout board for a MSOP-8 package. Credit BC Robotics

If you're super pressed for time, you can create your own breakout board using a perf board and some wire. It's messy and takes a decent chunk of time, but it works. For the board below, I super-glued the component onto a piece of plastic to elevate it, then soldered bits of wire to each of the pins.

A breakout board I MacGyvered together for a multiplexer using a perf board.

Use the multimeter to check the connectivity of your circuits and components

If everything is wired correctly but it still isn't working, check the connections of your soldered components using a multimeter in continuity mode. Some of your terminals may have been soldered together, or the connection may be poor enough to not transmit signal.

For PCBs, I recommend checking the continuity of each component as you solder them on, or at the very least before you leave the soldering station.