This analog frequency meter for low frequencies was found in Radio Electronics magazine from July 1958. The circuit has several scales with the frequencies indicated in the diagram.
This simple 80's CMOS game was found in an English magazine of the time. It appears elsewhere on this...
This circuit uses as an indicator a common micrometer type VU with 200 uA of full-scale current. The...
This circuit was found in ancient American documentation. Diodes are general-purpose types. |...