Power frequency detector circuit schematic

MOS power IC full range

Shunluo Inductance Power Inductor SWPA Series First Class Agent

Photocoupler

description:

Power frequency detector

For some electronic instruments and electrical equipment, there are certain requirements for the frequency of the six power supplies. If the power frequency is higher or lower than 50 Hz, it will affect the normal operation of the equipment and even cause damage to the equipment and equipment. Therefore, for such equipment, a power frequency detecting device is required. When the power frequency exceeds the required deviation range, the device can issue a warning or automatically cut off the power to ensure the safety of the device.

First, the working principle of the circuit

The power frequency detector circuit diagram is shown in the figure.

Power frequency detector circuit diagram

In the circuit, the first flip-flop IC-1 in the CD4013 forms a flip-flop to shape and divide the input power signal. The divided signal outputted by its Q1 terminal is used as the switching control signal of the light-emitting tube VT1. The second trigger IC-2 R3, R4, R5 and C3 form a frequency detecting circuit. When the power frequency exceeds the specified range, the frequency detecting circuit outputs a detection signal to turn on VT2 and cut off the power. When the falling edge of the output pulse of the flip-flop causes VT1 to be turned off, capacitor C3 is charged through R3, R4, and R5. If the power supply frequency is low, the charging time of the capacitor will be prolonged, and the voltage at the upper end of C3 will rise. The partial pressure with R7 turns VT2 on, the relay sinks, and its normally closed contact disconnects the power supply. When the power frequency is normal, because the switching transistor VT1 is turned off for less than the charging time constant of the capacitor C3, the charging voltage at the upper end of C3 does not reach the turn-on voltage of VT2, and the controlled device will work normally.

Second, the choice of components

There are no special requirements for components, which can be selected according to the figure.

Third, production and debugging methods

The component type and value of the circuit are marked in the figure and can be used without adjustment after assembly.

For related information on CD4013, please refer to: http://