This circuit was obtained from an American 1980s documentation. The frequency depends on the crystal and the circuit may be a PNP that reaches the generated frequency.
We found this circuit in Motorola's Linear Databook in 1990. Integrated circuits are somewhat...
This 0.5 Hz filter was found in the December 1990 issue of Radio Electronics magazine. The power...
Atmel's ATmega 324PB microcontrollers available from Mouser Electronics are RISC-based...