Precision 50Hz signal generator

This is a simple oscillator circuit that uses a crystal to generate a 50Hz frequency. It outputs a square pulse with a duty cycle of 50%. This square pulse is often used in inverters and precise clock displays. The oscillator consists of a 14-stage counter and oscillator chip CD4060, a dual J-K flip-flop CD4027, an operational amplifier LM324, and several discrete components.

The oscillator is made of a 3.2768MHz crystal and resistors and capacitors connected to the corresponding pins of IC1 (CD4046). Resistor R1 is used to limit the power and R2 is a bias resistor.

The 3.2768MHz oscillation frequency is divided 14 times and outputted at 200Hz on pin ③ of CD4060. This 200Hz frequency is then divided by 4 using the dual J-K flip-flop CD4027 to get an accurate 50Hz frequency. It is outputted from pin (15) of CD4027, while pin (14) outputs a 50Hz inverted signal. The duty cycle is 50%.

The 50Hz frequency output is buffered by the A1 and A2 operational amplifiers LM324, and two 50Hz square wave signals with opposite phases can be output from its pins ① and ⑦ respectively.