Low cost voltage and ammeter with dual electronic potentiometers

The voltage and ammeter with electronic potentiometer can be retrofitted to TL494 MEAN WELL and other power supplies. It is a multi-functional voltage and ammeter with electronic potentiometer function. If it is used to modify an adjustable power supply, it is best to use an encoder to control it, so I took some time to redesign the circuit and write a program. It can be regarded as an improved version of the button version. It is really easy to control with an encoder, with voltage, current, power, Capacity, power-on time and energy value display. It can also be considered as a sense of accomplishment by DIYing your own products. The dimensions of the board are 72mm x 32mm. It is very small and can fit most power supplies. The display size is 1.44 inches. The screen display area is approximately 3.2×1.5CM. The screen model is FM1721625, and it should be possible to use a 12864 serial port screen compatible with ST7567. If you have a screen similar to 12864, you can use it by changing the pins in LCEDA.
20220824 The latest version, you can adjust the maximum PWM output voltage in the software.
Dual electronic potentiometer. The encoder can be used to control the DV and DA outputs to a controllable 0~6.6 volt voltage. It can be used to replace those that use two precision multi-turn potentiometers and a voltage and current meter modification kit to convert the power supply of the TL494 chip into an adjustable power supply. use. The output of the rear stage has been amplified by the operational amplifier LM358. If a larger voltage is needed, by modifying the operational amplifier amplification resistor and increasing the amplification, the output can be from 0 to 10 volts.
It is specially designed for transforming TL494 power supplies such as MEAN WELL Power into adjustable power supplies. Of course, some communication power modules can also be used. As long as the reference voltage is adjusted to control the voltage and current, it should be possible in theory, but the kind that adjusts the output voltage sampling cannot. It replaces the mechanical double potentiometer and voltage and ammeter, and removes some useless functions. Only one voltage and current display is retained. For specific modification methods, please refer to the tutorial for mechanical potentiometers. For those who do not understand MEAN WELL power supply modification, please be cautious as there is no guarantee of success. The software is not perfect yet, the firmware is updated in 20220823. Corrected the problem of inaccurate voltage and current display in the charging control module. This error is caused by changing the baseline. Because the internal reference was used instead, and there was no synchronized change inside the charging and discharging module, the voltage and current display in the charging and discharging module was inaccurate. This has been corrected.