The circuit shown was found in Intersil documentation from the 90s. The formula allows to calculate the voltage obtained as a function of the values of the resistors.
Found in a 1966 documentation, this “coin finder” uses components from the era operating at 2.1...
This circuit has an interesting application. If a device with the selector switch in the 110 V...
This circuit uses an unusual Motorola voltage reference. Other manufacturers also provide this...