This Breadboard Buddy is an accessory for quick access to some commonly needed workbench peripherals while breadboarding projects.

KiCAD and other design files, including the ATTiny85 OLED sketch are available on GitHub:

https://github.com/GadgetReboot/Breadboard_Buddy

The board contains a SEPIC regulator (XL6009) to take in an AC or DC source (via bridge rectifier) and universally generate a steady voltage rail somewhere over 10 volts DC (adjustable higher with a pot).   I wanted to be able to use any wall adapter I had laying around that can put out maybe 7V to 20V, AC or DC, and as long as it can deliver enough current, I can use it to make life easy.

That voltage rail is then used as an input to a couple of LM317 linear adjustable regulators.  One can be adjusted more broadly while the other is locked to a max output of less than 10V because it feeds into an ICL7660 (with a max in of 10V).   This generates a negative rail from the positive input, so we get a +/- 10v or so output for things like op amps.

Then that +10V rail feeds into an LM1117 set to give +5v, which feeds to another LM1117 set for +3.3v.    So this should allow powering most breadboard projects, intending not to draw too much current overall so probably not designed to run heavy motors, just the control circuits.

I'm also using an OLED display to monitor/display the adjustable voltage rails so a multimeter doesn't have to be located and fumbled with when the voltage control pots are adjusted.

There are 20 on-board LEDs in the form of two 10-segment bar graph displays, which will have 0.1" headers for dupont wires to a breadboard.   Each group of 10 can be set for common anode or cathode.

There is an on-board LM386 audio amp, and an op amp mixer with 4 inputs, each with a level control plus an overall volume control.

There is a header for a speaker to be connected off-board.   This makes it easier to experiment with audio circuits.  

There are 8 bi-directional level shifters with headers to interface 3.3v and 5v logic.

There's space to populate two potentiometers, providing 0.1" headers to jumper the terminals to a breadboard for quick access.   No more fumbling around for a 10k pot that USED to be sitting RIGHT THERE on the workbench, until it was needed and was nowhere to be found.