This circuit was found in an old Electronic Design. It makes use of sidacs and operational not very common today. The power supply must be symmetrical.
Two operational are used on this triangular-rectangular oscillator suggested by Motorola in its...
This circuit from a Popular Electronics from the 90's can generate signals from 0.03 Hz to 3 kHz...
With 8 to 30 V power supply, the output power depends on both the voltage and the load. The...