This timer, like the previous circuits, uses a currently uncommon integrated circuit. The time is given by capacitor C1 and R2 which has the range of values indicated in the diagram.
In the figure a circuit that is the basic application of NE567 for the detection of a tone applied to...
This circuit is from an old Italian publication, using components that are no longer manufactured, but that...
We found this switching circuit in a technical documentation from National Semiconductor. The...