This circuit is from the 70s. The integrated circuit used is not common today and the supply is made with a voltage found in televisions of the time, where it was used.
This high-performance circuit was found in the 1982 SGS Linear Integrated Circuits Manual. The...
Found in a 90s Electronics Engineering, this circuit makes use of components of the time. The...
Found in a magazine 73 for radio amateurs, this circuit has two settings, one for the interval and the...