This filter has the components calculated for the frequency of 1 kHz but can be changed. The input resistor can be 100k and the source symmetrical. Any operational amplifier can be used.
The circuit shown in the figure is suggested by Allegro Micro (www.allegromicro.com) and consists of...
This circuit is a variation of the common grid dip meter, having been found in a 1975 publication on FETs....
The time obtained in this circuit, from a 1978 publication, depends on R3 and C. R3 can have...