We can bring the inverter CMOS digital IC is CD4049 Hex Inverting Buffer IC, to design the Square wave oscillator generator circuit diagram or Simple Pulse Generator circuits, to a lot circuit been simplified.
The circuit we use a little equipment, just add a resistor and capacitor are the only one,It uses less energy. The output frequency is relatively constant, the rate of change in frequency of the power supply voltage is less.
The pulse generators can also produce a 50% duty cycle square wave. The ICs in the circuit number CD4069,TC4069,LM4069.
The frequency determined by R1 and C1 is F = 1 / (1.39xRxC). The power supply used DC 3V-12Volt.