This 5.1 MHz circuit was found in a 1980s documentation. The frequency is given by the crystal and general purpose transistors can be used.
The circuit bellow shows how four inverters [NAND, NOR or Inverters] Kim - This could be NAND,...
This circuit, from a 1978 publication, emits a modulated signal when the fine sensor is...
This commercial radio was manufactured in Japan in the 1960s. The circuit uses 4 transistors and...