In the figure we have a basic oscillator with inverters obtained from TTL, CMOS or other gates. The graph on the side allows to find the frequency depending on the resistor and the capacitor.
This circuit is from a 1980s Motorola documentation. The circuit can be made with modern...
This well-known circuit triggers a relay when light striking the phototransistor is cut off. The...
This circuit generates a pulsed tone whose frequency depends on C2 and whose flashing depends on...