The circuit shown is from a 1994 National Semiconductor documentation and can be implemented with more modern operational amplifiers. The power supply must be symmetrical.
Found in Motorola documentation from the 90's, this circuit charges the capacitor with a constant...
This circuit has two high-impedance inputs. The gain is high and more inputs can be added. Use a...
We found this circuit in the Philips Databook of 1990. The circuit is indicated for low-cost...