This circuit, found in a 1958 magazine, is for reference only, since the components are not easy to find today. The transistors are germanium types and power supply is made by common cells.
Although it is a configuration still known today, this is from a Japanese publication from 1960....
This circuit was found in an English documentation from the 90's. Equivalent components such as...
This speed control for small DC motors can operate from 6 to 12 V sources. The motors can drain...