This circuit uses a feedback integrator. We found it in Ferranti's transistor manual from 1974. Transistors are general-purpose types at the time.
This circuit was found in an old Popular Electronics. With it we can check the operation of a...
This circuit can be used in measurement bridges. We found it in the September 1995 Electronics Now magazine....
This circuit is from a 1965 General Electric publication. It uses a thermistor to fire a reed...