Found in a 90s Popular Electronics, this circuit uses a 741 to generate frequencies from 0.1 to 30 Hz. Observe the phototransistor feedback.
This circuit was found in Motorola documentation from 1968, using high power transistors and...
This circuit appeared in the November 1995 issue of Electronics Now magazine. The circuit uses...
This is one of many versions of this circuit that the reader can find in this section. The circuit...