This filter was found in an 80's English publication. However, it can be implemented with modern operating systems. The circuit can tune frequencies in a range from 10,000 to 1.
This circuit can function as an output shield for microcontrollers, being compatible with TTL...
This circuit is from a 1979 publication, using displays of 7 segments of common cathode. The...
This circuit is from an English publication of 1982. The bipolar transistor can be a BC548 and the...