This circuit was found in Ferranti's 1974 transistor manual. The transistors are from the period and the frequencies generated are between 50 Hz and 2 kHz.
This very low frequency oscillator was found in a Popular Electronics from the 90s. The circuit...
In the figure we have an active high pass filter of 100 Hz, suggested by National Semiconductor in its 1994...
Constant currents from 10 mA to 1 A can supply the load, depending on the selection made by S1. Q1...