The circuit presented was found in the Linear Applications Handbook of the National Semiconductor of 1994. It is based on a DAC1020 and operational not common today.
This circuit was found in a 1960s book of projects by Gernsbak. The circuit uses germanium...
This circuit was originally designed for testing crystals used in color televisions, but it works...
The circuit of a 1968 publication can be implemented with more modern transistors such as BC548 for...