This simple metronome, from 1985 documentation uses only transistors and has two settings. For voltages above 6 V, up to 12 V, replace the BC557 with a BD136.
This circuit is from American documentation from 1973. It can be used to indicate when the logic...
This circuit is from an old documentation. However, it can be mounted with modern equivalent...
This interesting circuit, found in an old American publication, measures alternating signals in a...