Low-Cost Cryocooler Pumps Out Cheap DIY Liquid Nitrogen

A word of caution if you’re planning to try this cryocooler method for making liquid nitrogen: not only does it involve toxic and flammable gasses and pressures high enough to turn the works …

Low-Cost Electret Microphone Preamplifiers

Before the invention of microelectromechanical system (MEMS) microphones, almost all microphones in cell phones and other electronics were a type of condenser microphone called the electret microph…