Wireless remote control plus/minus resistance network circuit

In electronic circuits, potentiometers are very commonly used, and many power adjustments are made by adjusting resistors. The wireless remote control resistor network introduced in this article uses two control keys to increase or decrease the resistance of the resistor network, with a total of 16 resistance changes. Like a potentiometer, it can be used in automatic control systems, electronic instruments, medical instruments, AC voltage regulation, volume adjustment of electronic toys and audio equipment, etc. The transmitting circuit is shown in Figure 1. CD40193 is a dual-clock 4-bit binary synchronous up/down counter. Its functions are as shown in the attached table. CPU is the addition clock pulse input terminal, and CPD is the subtraction clock pulse input terminal. When 0 to 15 count pulses are input in sequence, its output terminals Q3 to Q0 change in sequence from 0000 to 1111 (addition) or 1111 to 0000 (subtraction). This binary data is added to the D~A terminals of the wireless transmitting component TWH9236 (including built-in antenna), and is emitted outward by the built-in antenna. The two NAND gates of the CD4011 chip form an ultra-low-frequency oscillator, which provides counting pulses to the CPU or CPD end of the CD40193; the other two NAND gates form the addition and subtraction counting gates. When S1 is pressed, the subtraction counting gate is opened, and the CD40193 proceeds. Counting down, when pressing S2, the adding counting door is opened, and CD40193 counts up. The working voltage of CD4011 and CD40193 is 5V, which is stabilized internally by the transmitter component TWH9236 and then sent out through the E terminal. The frequency of the ultra-low frequency oscillator is preferably 0.5~2Hz. The receiving circuit is shown in Figure 2. TWH9238 is a wireless receiving component (including built-in antenna), and its receiving frequency has been paired and adjusted with the transmitting component TWH9236 at the factory. The output levels of Q3~Q0 correspond to the D~A input terminals of the transmitting component TWH9236 one-to-one. The resistance of the resistor network composed of R01~R04 is controlled by turning on and off the four switches in the four bidirectional analog electronic switches CD4066. RAB. R01 ~ R04 take values ​​according to binary digits, and there are 16 resistance changes. When counting up, RAB changes from 15kΩ to 0; when counting down, RAB changes from 0 to 15kΩ, and the step value is 1kΩ. In specific applications, the values ​​of R01~R04 can be changed according to the ratio of 1248 to obtain appropriate RAB values ​​and step values. Figure 3 is a specific application circuit, in which terminals A and B are connected to terminals A and B in Figure 2 respectively. Pressing S1 or S2 in Figure 1 can adjust the luminous intensity of the light bulb EL. V (BT33), C1, RAB (resistance network), etc. constitute the trigger circuit of the triac VS. When RAB selects different resistance values, C1 will have different charging currents, causing the conduction angle of VS to change, so it can be adjusted EL brightness.