Dual Polarity Power Supply
Two versions of a dual polarity power supply with printed circuit board artwork. The supplies are built around the popular LM317 & 337 complementary voltage regulators which offer very high ripple rejection as well as short-circuit and thermal protection.
A battery-powered microphone preamplifier and microphone wand for acoustic tests and recording. The preamplifier features 20dB of switchable gain and a clipping indicator,
Jason Neals DIY Audio and Electronics
An interesting website with many photos of electronic projects. There are not many projects but the description and photos and documentation are very useful for learning the art of circuit design.