Integrator with bias compensation (CB20991E)

This circuit was found in a Popular Electronics from the 90's. It can be implemented with equivalent operational amplifiers.

Small Current Meter (CB14857E)
This circuit is designed to measure very weak currents, in the nanoampères range, using the 1 V...
10 Channel Remote Control Decoder (CB9984E)
This circuit consists of a decoder for remote control that allows the activation of 10 channels based...
10 to 150 kHz Crystal Oscillator (CB6183E)
This circuit is from a 60's documentation. The capacitance C1 can be between 20 pF and 0.01 uF...