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.
This circuit is from Popular Electronics from October 0, 1981. The diodes can also be 1N4004 and...
This switch or band selector for receivers was found in a Popular Electronics from the 1990s. The...
This circuit, published in 1978, can use any general purpose NPN transistor such as the BC548 and...