This circuit, found in a 1958 magazine, is for reference only, since the components are not easy to find today. The transistors are germanium types and power supply is made by common cells.
This circuit is suitable for modulating AM transmitters. The circuit is from a 1977 radio amateur...
This double tone generator uses a specific integrated circuit, having been found in a 1977 CMOS...
This is a simple 1-digit voltmeter circuit using voltage comparators. It was found in a 2004...