555 square wave oscillation circuit

To get a square wave output, the circuit in Figure 9 can be used. It is composed of a diode VD connected in parallel to both ends of RB based on the circuit in Figure 8. When RA =RB, the charge and discharge time constants of C are equal, and the output will be a square wave. The frequency of the square wave is f=0.722 / RAC ( RA =RB )

The diode method can obtain a pulse oscillation circuit with an adjustable duty cycle.

On the basis of this circuit, add potentiometers in the RA and RB loops and use series or parallel connection.

The 555 pulse oscillation circuit is often used as an AC signal source, and its oscillation frequency ranges from a few tenths of a Hz to several MHz. Because the circuit is simple and reliable, it is widely used.