This circuit rejects frequencies around 1 kHz and can be adjusted using C1. Equivalent operational amplifiers can be used, and the power supply must be symmetrical.
Found in American documentation from the 1980s, this circuit can be designed with equivalent...
The 4028 CMOS IC not only contains the complete decade counter, but also the 7-segment decoder...
We found this circuit in an American 1980s documentation. The circuit can be assembled with modern...