This filter was found in Texas Instruments documentation from the 1980s. The circuit uses a common operational amplifier and has its response curve in the figure.
This low voltage lamp flasher can be powered from 12 V supplies. Frequency is adjusted by P1 and...
The transistors in this circuit, found in an American publication in 1975, can be replaced by...
This circuit, from an old publication, can also use modern transistors. Note that the unit is...