NE555 electronic windmill

This is a device that uses electronic circuits to replace the windmill that rotates with the wind. The windmill blades are simulated by four LED light strips. When there is wind, the four light strips light up in turn, forming a rotating state.

The wind sensor needs to be made by yourself. After testing, a small electric bead of 6V/30mA was finally selected. Carefully break the glass shell and keep the filament. Use the filament as a wind sensor. Its sensitivity and response are excellent.

The circuit is attached. Wind sensor S1 is connected to the positive pole of the power supply through the current limiting resistor R1, so that it works at 1.35V, 30mA; LED1 is used to monitor whether the filament of S1 is disconnected. When there is no wind, the voltage at the output terminal TP1 of the op amp IC1b is 4.0v, and when there is wind (about 1m/s), it is 6.0v.

To avoid the influence of room temperature changes, AC coupling is used at the input end; the coupling capacitor C1 has a large value. The time constant formed with R4 is about 1s, ensuring that the voltage change caused by breathing towards the sensor can pass. Transistor Tr1 and its surrounding components form a forced charging circuit for C1 to minimize the time for C1 to enter a stable state; the excess current is shunted by D1.

The voltage change detected by the wind sensor is amplified by about 20 times by the op amp IC1a; adjusting the potentiometer at the in-phase input of IC1a can control the static DC bias of the 555 circuit. D2, C3, and R6 form a circuit to simulate the inertia of a windmill, and C3 is not connected in the figure.

In the stable state, use VR1 to adjust the voltage of pin 7 of IC1a to 4.0V. Then change this voltage between 3.8V and 4.2V until the LED is just visible. Connect LED2 as a coupling element between IC1b and the subsequent circuit to generate a potential shift of about 2V. The output voltage is directly used for the charging control of 555.

The 555 time base circuit is connected as a deformed self-excited multivibrator. It generates a PWM waveform corresponding to the rotation of the LED. When the potential of the 6th pin of the 555 exceeds 2/3 of the power supply voltage, the 7th pin is in a discharge state and the internal trigger is reset; otherwise, the trigger is not reset, the 555 does not output pulses, and the output terminal is in the "H" state.

IC3 is a four-state pulse counter 4022. Connect its Q4 and R terminals to reset; Q1, Q2, Q3 and Q5 drive four LED light strips respectively, making them light up in sequence. The 12 LEDs are divided into four columns, distributed like the four blades of the windmill. The windmill power supply uses a three-terminal regulator. 7808 provides +8v power supply.