Why make your own power supply?
This power supply is based off of a wave rectifier design and converts 12VAC from a wall wart into dual rail +12VDC and -12VDC. My reasoning for building my own supply vs. buying an off the shelf unit is primarily noise. Since this supply will be used to power my modular synth project, the power needs to be extremely clean. Any noise in the power supply will translate directly to the audio being heard on the speakers. While the wave rectifier is not the most efficient power supply design, large capacitors allow for a clean output. The power supply simply rectifies the AC sign wave into its positive and negative components, smooths the sign wave with the capacitors, and regulates the voltage using voltage regulators. I have also added a 5V voltage regulator for powering Arduinos.
CEM 3340 Oscillator Prototype
The purpose of the power supply is to power other modules of the modular synth. The first module that I am implementing is an oscillator, which is the core of any synth. Future modules will include filters and sequencers. The oscillator is based off of the CEM 3340 chip which was found in many synths in the 70s such as the Moog Memorymoog, Roland SH-101, and Sequential Prophet 5. The oscillator core exists inside the IC as this is a purpose built oscillator chip. It outputs a square, triangle, and saw-tooth waves. Currently I am implementing an OP-AMP buffer into the circuit to prevent output devices from interfering with the circuit. My current progress is pictured on the right