Found in a 1969 Burr-Brown publication, this circuit makes use of integrated components from that period. With modern equivalents, it can be adapted to be used as a shield.
Other series amplifiers such as the MC3301, MC3401 and LM2900 can be used on this circuit. We...
This configuration, widely used in our articles and on this website, uses a 555 to control a relay...
This circuit was found in an English documentation from the 90s. It uses a PLL CMOS 4046 and is...