Building a Smart Electronic Load | 2026 Update (#3)

Hi E14 Community!  Wanted to give a quick update on my Smart Electronic Load project.

Since the last time from one year ago, Building a Smart Electronic Load | DAC and Initial Firmware (#2), the project was progressing relatively slowly, but now in the winter holidays I had a bit of time and I managed to get the load into a stable working state. Back in November I also ordered new PCB-s for a hardware revision 0.2, fixing the biggest deficiencies of the first iteration. Bellow I list some of the changes made.

Hardware changes (rev 0.2):

• Added Load Enable/Disable MOSFET-s (for protection when no input is connected
• Redesigned the Current and Voltage sense circuits (added opamps buffering to improve stability)
• Duplicated the Current Sense resistor footprints to offer better thermal dissipation
• Removed/simplified some unneeded parts (offset adjustments, etc.)
• Fixed some bugs (RX/TX lines used for DAC), introduced some new ones (:D) and fixed them in rev 0.2b

Rev 0.2 PCB (with consolidated current path:

Software improvements:

• Created a simple Web UI with basic controls
• Rewrote the control loop with RTOS tasks and added continuous ADC readings running at 16kHz
• Added Constance Power (CP) and Constant Resistance (CR) modes, alongside the existing Constant Current (CC) mode
• Implemented basic set of Protections for Over Voltage, Over Current, Over Power and Over Temperature
• Implemented initial support Current Pulses (transient) and shaping
• Added basic Calibration support (for voltage and current sensing)
  
  

Web UI:

Testing:

• Tested load stability for the entire voltage and current range, and load is now stable at 100kHz. At 470kHz the load is partially stable (oscillations appear at some voltage ranges)
• Tested temperature stability:
  • Big load thermally stable at 125W continuous, support up to 300W.
  • Small load thermally stable at 50W continuous, supports up to 200W

Temperature curve of the Big load, 125W, 10V @ 12.5A, 100% fan speed:

Some plans for this year are:

• Try some faster op-amps with stabilize the load ~500kHz
• Implement more advanced Pulse / Current Shaping functionality (the software should be capable to drive the DAC at up to ~4MHz)

Git repo: bluetiger9/SmartElectronicLoad

Hope you enjoyed this update! 

PS: I've a couple of semi-assembled PCB-s (rev 0.2) left over. Feel free to drop me a message if you want one!