Overview
The Simple Bipolar Supply is a USB-C powered dual-channel module that gives a positive and negative rail with respect to ground. It’s designed as a drop-in for any project that needs a bipolar supply, and as a set of building blocks for a supply tailored to the application.
The current version steps the USB 5 V through an LM2776 charge pump for the negative rail and pi-filters both outputs, on a board with breadboard-friendly pin spacing. The roadmap adds regulation, variable output and protection stages for a regulated, adjustable version.
- KiCad
- Charge pumps
- Filtering
Gallery
Updates
-
Rev C: fixing low-load ripple
At no load, the charge pump showed about 70 mV peak-to-peak of periodic (20 Hz) sawtooth noise on the negative rail. Drawing about 20 mA through a parallel LED cleared it, so Rev C adds indicator LEDs as a permanent load, increases the charge pump’s input capacitance and adds part numbers throughout.
-
Rev B
Removed the castellated edges, made a new module symbol and footprints, and tweaked the layout.
-
Rev A layout
Placed components with pin spacing optimised for breadboard use, then routed the board and finished the silkscreen and branding.
-
Rev A schematic
Started the project and completed the first schematic.