This filter, which rejects frequencies around 1 kHz, was found in the August 1993 Electronics Now magazine. The fine tuning is done at R3, and the source must be symmetrical.
Suitable for battery powered microcontrolled applications this Texas Instruments circuit from its...
This amplifier with the LM1098 and LM101 by Motorola from a 1990 manual can be designed with more...
Found in a 1967 Ferranti documentation, this circuit uses a LDR from that time as a sensor....