This circuit, suggested by an Electronics World of 1969, keeps a blinking LED for a while when a power outage occurs. Time depends on capacitor C1.
This filter was found in an 80's English publication. However, it can be implemented with modern...
This circuit, which can be used as a shield, was found in old documentation. The circuit must be...
Found in Philips documentation from 1968 this circuit operates at frequencies up to 10 MHz with 76...