I have been moving away from THT to Surface Mount over the past year, once you learn how to solder them they are not that difficult to use and offer many advantages over THT including the range of components, price, availability and reduced PCB size. I still need to breadboard experimental circuits (or 'Version 0' of a prototype) and SMT parts are not overly friendly in that regard. I wound up making a set of DIP style breakouts for various SMT formats (SOIC, TSSOP, QFN, etc) but that still left the issue of discretes.

3.3V Regulator

Inspired by this project on Hackaday I designed a small multi-purpose breakout that supports a single SOT-23 or SOT-223 component as well as up to 5 discretes (LEDs, resistors, caps and diodes). This board (that I'm calling MultiBOB) not only lets you use individual discrete components but is flexible enough to build up small circuit blocks such as regulators, high and low side switches and other simple circuits.

The image above shows the layout and soldered version of a simple 3.3V voltage regulator based on the MCP1702 LDO component. Here are a few more examples:

Discretes

To the left is a simple voltage divider circuit to bring an input voltage down to a suitable range for an ADC or to use as a simple voltage level shifter. The circuit on the right is a simple 2 LED driver.

MOSFET Switches

A high and low side switch for controlling higher voltages. The high side switch is active low so you would need to use a low side switch to pull the input down to activate it.

LM317

Circuits for constant voltage and constant current regulators using a LM317 in SOT-223 format.

This is a first cut at the design so it is not without issues (althought it is still usable in it's current state). I added a ground plane to the bottom copper layer but inadvertently connected it to pin 1 of the 3 pin connector which is not always the ground pin. In a redesign I'll leave it disconnected and allow for any pin to be connected to it via a solder blob jumper.

Solder Blob Jumpers

The solder blob jumpers themselves don't really function as expected either. The pads are a little bit too far apart and the solder resist on the PCB make it difficult to solder them together. A workaround is to simply solder a small piece of wire across the 0805 pads instead.

The schematics and board layouts for all the breakouts are available on GitHub. I use DesignSpark PCB for schematic capture, the software is free but for those that prefer not to install it I have included a ZIP file containing the gerbers in each directory.

As a bonus there is a small Python script in the samples directory that will generate board layout images like the ones in this post for you. Look at the README.md for instructions on how to use it. Please feel free to share your designs on The Garage Lab space or submit a pull request with your design description fle.