The use of field effect transistors in this circuit improves its performance. This configuration is from a 1975 circuit manual. The transistor can be any general-purpose FET such as MPF102 or BF245.
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...