This circuit is from old documentation, but it can be implemented with modern transistors such as 2N2222 for bipolar and BF124 for FET. The crystal determines the operating frequency.
This circuit is from a Radio Electronics from April 1965. It uses an incandescent lamp, and the...
This circuit was found in a 1968’s publication and uses germanium transistors. The characteristic...
This is a single IC voltage regulator that can acts in the range from 1.2 to 20 V. Output currewnt is up to...