Analyze DC-DC Converter Efficiency with This DIY Electronic Load

A scratch-built electronic load with LCD display, custom PCB, and salvaged heat sink.

JeremyCook
over 5 years ago

If you want to know more info about your power supply or battery capacity, an electronic load is a useful piece of test equipment to have available. While simple in concept — a resistor that lets a set amount of current flow — varying this load, and allowing sufficient cooling so that it doesn’t overheat takes a bit of finesse.

For an idea of how to make such a device from scratch, check out this build by “reivax-boucoi," which was constructed for DC-DC converter characterization. It uses an ATmega328P microcontroller to interface with an MCP2221A I2C DAC for control, plus an LTC2992 power monitor chip. User input is provided by a rotary encoder, with a button for load on/off and another to jump to the previous menu. Feedback is via a 16x2 LCD.

Input voltages of 0-100VDC can be tested, with load currents of 5mA-5.25A selected in 8mA steps. The device requires a restart after changing settings in order to help avoid accidents.

A delightfully large heat sink was salvaged from an old graphics card for cooling, along with a PC-style fan. PCB design files and firmware are available on GitHub. However, since the heat sink was just pulled from spare parts, this may present an issue for anyone trying to directly duplicate the design. The project looks like a great template, though, and a little PCB and/or heat sink modification seems only par for the course!

JeremyCook

Engineer, maker of random contraptions, love learning about tech. Write for various publications, including Hackster!

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