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.
Found in a 1970 EEE, this circuit uses general-purpose transistors of the time. Transistors support...
This simple source using fixed voltage regulators can supply currents up to 1 A at the voltages...
Originally suggested by Harris in the 1990s, this circuit uses an optical tachometer. The circuit is...