Remote control modification of old-fashioned electric fans

An old-fashioned table fan with push-button three-level wind speed adjustment has been modified by the author to have three-level remote control adjustable wind speed and remote control functions such as natural wind and sleep timing. The control circuit uses a full hardware circuit. The circuit is as follows As shown in the figure. Although the principle of this control circuit is very easy to understand, it is obviously much more complicated than a circuit with similar functions controlled by a microcontroller. It can be seen that for beginners who are not familiar with microcontrollers, it is easy to understand the control process by modifying an old-fashioned fan with reference to this circuit. On the other hand, comparison also shows that if you want to make a simpler hardware circuit have more control functions, the best choice is to use a single-chip microcomputer. Therefore, beginners who are still unfamiliar with microcontrollers must enter the world of microcontrollers as soon as possible. This control circuit is introduced as follows. 1. Remote control receiving circuit. It is composed of infrared receiver REC and IC1 (555). Normally, the REC output terminal is high level and is controlled by the home appliance remote control. Each time the remote control button is pressed, the REC output is low level. IC1 forms a monostable circuit. Every time the remote control button is pressed, IC1③ pin outputs a positive pulse, which is added to the IC2 (4017) pin. 2. Normal wind control. When powered on, the power-on clearing circuit of IC2 makes the Q0 terminal high, and the LED1 connected to it lights up. When the remote control is pressed for the 1st to 3rd time, Q1~Q3 of IC2 will be high level in sequence, controlling the fan to operate at high speed, medium speed and low speed respectively. 3. Natural wind control. Press the remote control for the fourth time, Q4 of IC2 is at high level, causing the multivibrator composed of IC3 (555) to start oscillating. The first to fifth pulses output by pin ③ of IC3 make Q1 to Q5 of IC4 (4017) in sequence. High level, the 6th pulse resets IC4, and Q0 is high level. In this cycle, the fan circulates from high speed to medium speed to low speed to inertial rotation to stop to send out natural wind. 4. Sleep wind control. Press the remote control for the fifth time, the Q5 terminal of IC2 outputs a high level, 3DG12 is turned on, J1 acts, J1-1 is closed, the IC3 oscillator oscillates under the control of the Q0 high level of IC5 (4017), and the fan still operates according to the natural wind mode operation. J1-2 is closed, the light-emitting diode of the optocoupler 4N25 is turned on in the positive half cycle of the mains power, and is turned off in the negative half cycle. There is a 50Hz pulse input at the CP end of IC6 (4040). IC6 is a 12-bit binary counter, counting 3000 pulses ( Time 60 seconds), point A is high level. On the one hand, this high level resets IC6 and restarts counting. On the other hand, it is added to the CPOA end of IC7. IC7 (4518) is a dual binary-decimal counter, which is cascaded here to form a two-digit decimal counter. After 45 minutes, the CPOA terminal of IC7 inputs 45 pulses. At this time, the status of Q3A, Q2 A, Q1A, and Q0A representing the ones digits is 0101 (decimal number 5), and the status of Q3B, Q2B, Q1 representing the tens digits B、Q0B The status is 0100 (decimal number 4), and a high level appears at point B. This high level resets IC7 on one hand and sends it to the CP0 end of IC5 on the other. Q1 of IC5 is high level. After the second and third 45 minutes, Q2 and Q3 of IC5 are high level in sequence. Since the resistance values ​​of the Q0~Q3 terminals of IC5 are different, the oscillation frequency of IC3 is different, so in the "sleep" state, the sleep wind generated in each period is also different. When the fourth 45 minutes arrives, Q4 of IC5 outputs a high level. This high level is added to the prohibition pin of IC5 to keep Q4 at a high level. At the same time, it is also added to the MR end of IC4 to reset IC4. The fan stalls. Press the remote control for the 6th time, the Q0 terminal of IC2 is high level. (Editor's note: When using, the AC220V input ground terminal in this circuit should be connected to the neutral terminal of the mains.) 