This 1/2 hertz high selectivity filter was found in the December 1990 issue of Radio Electronics magazine. The source must be symmetrical. The capacitors can be changed for other frequencies.
We found this CMOS circuit in a publication from the 1980s. What this circuit does is to flash two LEDs...
This 20 MHz bandwidth circuit was suggested by the National Semiconductor in 1970 documentation. Modern...
This conventional filter circuit is from American documentation from the 1990s. The operational amplifier...