Found in a 1967 American electronics magazine, this circuit has an input impedance of 2000 ohms. The circuit can be built with modern equivalent transistors.
Found in a magazine 73 for radio amateurs, in a 90's edition, this circuit uses a general-purpose FET...
The selected circuit causes a 12 V lamp with a current of up to 500 mA for the BD135 transistor to flash at...
This is one of the many applications of the 555. We found it in the November 1992 Radio...