OpAmp Oscillator 1
Simple square wave oscillator with a single opamp. Although the diagram shows a 10 supply, any supply the opamp can handle is acceptable. Adjust R and C to adjust the frequency. You can also adjust the left-side voltage divider resistors in order to effect the duty cycle. The other two resistors will also have some effect on oscillator frequecy. This is a fairly common circuit that has served me well for years. Very good for low power applications (much lower than comparable 555 circuits). This circuit also performs very well at extra lower frequency oscillations (on the order of seconds or longer) where other circuits don't. The upper limit of oscillation frequency seems to be limited to the device abilities. Check outversion 2of this circuit.