Found in Exar documentation from the 1980s, this circuit has a 60 dB cutoff at 1800 Hz. The circuit can be adapted to operate at other frequencies.
This sophisticated circuit is from old Motorola documentation, using common integrated devices...
This ultra-simple 9 V power source was obtained in an Argentine publication of the 1970s, but it...
Microsemi Le87536 Dual Differential Amplifier Microsemi / Microchip is making available through Mouser...