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.

Keyboard Hexadecimal Encoder (CB13763E)
We found this CMOS circuit in a 1978 publication. It allows you to use a standard calculator...
Silicon Oscillator for Microcontrollers (CB15598E)
In the figure we have an oscillator for microcontrollers capable of operating in the frequencies of 10,...
Fast trigger (CB21482E)
This fast Schmitt trigger operates at frequencies from 10 Hz to 100 Hz, with very short rise time....