This circuit activates a relay after a time given by C1 and R1. The circuit is from a Radio Electronics from December 1974. The relay voltage is the same as that used in the power supply.
We found this circuit in an old 1980s documentation. The circuit can be implemented with modern...
This circuit is from a Linear datasheet. The circuit provides a 5 m voltage with 40 mA from an AA...
The components of this filter are calculated using conventional formulas (see mathematics section of...