This post was last edited by lanhua on 2022-8-30 13:22
Fully automatic electric fan
Participate in the "Hands-on Learning about Power Supply Season 1: DIY small fan, fan all summer!" of "Electronic Engineering World", which will exercise both your brain and hands.
Special thanks to Electronic Engineering World for “Hands-on Learning about Power Supplies Season 1”!
The fully automatic electric fan is composed of a circuit board with FM5001 as the main chip, a human infrared sensor HC-SR501 , a KA555 multivibrator, a wireless charging module and other parts provided by "Electronic Engineering World" . After the power switch is turned on, the electric fan will automatically turn on and generate simulated natural wind when a human body is detected, and the fan will automatically turn off when the human body leaves.
1. Introduction to FM5001
FM5001 is a power management IC that integrates lithium battery charging management, lithium battery protection, DC-DC boost current limiting, and 3-speed adjustable air volume fan drive functions; it is dedicated to portable fans powered by lithium batteries.
FM5001L integrates the whole process of trickle charging, constant current charging and constant voltage charging, with charging indicator and full power indicator; supports fan drive function, built-in 3-speed adjustable air volume control, and supports discharge LED indication; when the battery voltage is less than 2.9V, the FM500 system enters the undervoltage state, and the current of the whole system is 30uA; built-in constant current charging current is 600mA.
FM5001 has multiple protection designs, including load overcurrent protection, anti-backflow protection during charging, short circuit anti-lock, soft start protection, lithium battery over-discharge protection, over-temperature and under-voltage protection, etc.
Fan circuit schematic, see Figure 1
Fan PCB diagram, see Figure 2 and Figure 3
2. Human infrared sensor HC-SR501
Module Features
1. The human body has a constant body temperature and emits infrared rays with a specific wavelength of about 10UM.
2. The human infrared sensor HC-SR501 probe is designed to detect human radiation, so the pyroelectric element must be very sensitive to infrared radiation with a wavelength of about 10UM.
3. In order to be sensitive only to the infrared radiation of the human body, its radiation surface is usually covered with a special Fresnel filter, so that the interference from the environment is significantly controlled.
4. Passive infrared probe, the sensor contains two pyroelectric elements connected in series or in parallel. The two electrodes are made with opposite polarization directions. The background radiation has almost the same effect on the two pyroelectric elements, which cancels out the pyroelectric effects, so the detector has no signal output.
5. Once a person invades the detection area, the infrared radiation of the human body is focused by part of the mirror and received by the pyroelectric element. However, the heat received by the two pyroelectric elements is different, and the pyroelectricity is also different, which cannot be offset. After processing, a control signal is output .
Human infrared sensor HC-SR501, see Figure 4
The control circuit is composed of transistors, etc., as shown in Figure 5
KA555 multivibrator
The low-frequency astable multivibrator with a large duty cycle is composed of KA555 and a small number of electronic components. It sends out pulses at intervals of several seconds to control the electric fan to produce simulated natural wind.
Circuit schematic, see Figure 6
Circuit board diagram, see Figure 7
4. Wireless charging module
Transmitter module diagram, see Figure 8
Receiver module diagram, see Figure 9
5. Machine control points
Control chart, see Figure 10
6. Video effects also require a protective cover
See Video 1 and 2
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