DC Electronic load

More info about this project can be found on my channel:

https://youtu.be/NScaRQj53l0

Used tools:

                   

Project status: ✔️ ready for construction!

The project is poised for construction and operational use. However, ongoing development persists, addressing minor bug fixes and introducing new features. Stay tuned for updates!

Project overwiev

Commercially available electronic loads often come with a hefty price tag, so I decided to build my own.

Project Goals:

• 300 W power dissipation

• up to 8A and 50V (obeying the 300W limit)

• Remote voltage sensing option

• Easy to input values: you can use an encoder as well as a keypad

• 5 modes of operation

  • Constant current mode

  • Constant power mode

  • Constant resistance mode

  • Transient response mode

  • Battery testing mode

• Nice to look at: doesn't look like a poor DIY build

Electronics:

There are two PCBs:

• Main board: responsible for main funcionalities of the load

• Front board: responsible for user input with the rotary encoder and switching the voltage measurement circuitry between the main and sense terminals

Mechanical construction:

The case for this project is made with 1mm thick bent sheet metal, with a 3D printed front panel.

Uploading the code using USBASP

add following code to the platformio.ini file

upload_protocol = custom
upload_port = usb
upload_flags = 
    -C
    ${platformio.packages_dir}/tool-avrdude/avrdude.conf
    -p
    $BOARD_MCU
    -P
    $UPLOAD_PORT
    -c
    usbasp
upload_command = avrdude $UPLOAD_FLAGS -U flash:w:$SOURCE:i

Uploading the code this way will reduce the boot up time.

Note: since this method removes the bootloader, in order to program the uC via UART next time, you have to burn the bootloader.

What could be improved in the next version:

• Add reverse polarity protection
• Higher resolution DAC

Special thanks

Special thanks to Eryk Możdzeń, who helped solving a software problem with a memory leak.