This circuit was found in a Popular Electronics from the 90s. The transistors are general purpose, and the gain depends on the ratio between R2 and R1.
This was the original title given by the publication of the 80s in which we found it. Similar...
This circuit is from the 1983 Intersil manual. The display is a 4.5-digit LCD, and the power...
This V/F converter was published in the June 1991 issue of Radio Electronics magazine. The...