This circuit is from a National Semiconductor manual from the 1980s. The integrated circuit is rare today and next to the diagram we have the formula for calculating the components.
Common operational amplifiers like the TL series, CA3140 and others can be used in this circuit...
This high-gain amplifier was found in the March 1994 issue of Electronics Now magazine. The...
We found this timer for times of a few minutes in a 1974 Ferranti transistor manual. The relay is 37...