Summary of USB Power supply Active Load Tester
This article describes a low-cost, open-source USB Power Supply Active Load Tester (PAL Tester) designed for simultaneous voltage and current measurement. The modular device supports up to 55V and 5A loads with under 5% accuracy, featuring an integrated USB-to-Serial converter and PC API for data recording. All source files are available on GitHub.
Parts used in the USB Power supply Active Load Tester:
- PIC16F1829 microcontroller
- MCP6002 Rail-to-Rail OpAmp
- MCP4726 12bit DAC
- IRF L3705 Logic Level N-MOSFET
- CH340T USB-to-Serial converter
- 10x 1 ohm 1% 1/2W resistors
- Miscellaneous resistors and capacitors
USB Power supply Active Load Tester or short PAL Tester is unit designed for testing the quality of the power supplies.
Idea was to create low-cost, precise device for simultaneous measurement of Voltage and Current drawn from the device under test. This is one of my weekend projects that I have decided to release to the public. All source files can be found on projects GitHub page.
Device Features:
- Open Source and Open Hardware
- Modular design, easy to understand and change/adapt to your needs
- Uses widely available and off-the shelf components
- Components Bill of Material is below $10
- Integrated USB-to-Serial converter for easier interface with the device
- API for communicating with PC
- Recording Voltage vs Amps data and graphing the results
- Easy to use
Basic capabilities:
- PSU under test max voltage 55V
- Current Load of 5A (or more by changing Rs value)
- Current and Voltage measurement accuracy is below 5%
Component list and estimated price:
- 1x – PIC16F1829 [$1.6]
- 1x – MCP6002 Rail-to-Rail OpAmp [$0.69]
- 1x – MCP4726 12bit DAC [$0.96]
- 1x – IRF L3705 Logic Level N-MOSFET [$0.5]
- 1x – CH340T USB-to-Serial converter [$0.99]
- 10x – 1 ohm 1% 1/2W resistor
- miscellaneous (resistors and capacitors)
How to build your own USB Power supply Active Load Tester:
If you are going to use photo etching or toner transfer method to make DIY board, there are bottom layer printouts in the Hardware folder that are ready for you to print and create a board via your favorite PCB manufacturing technique.
For More Details: USB Power supply Active Load Tester
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What is the primary purpose of this device?
The unit is designed for testing the quality of power supplies by simultaneously measuring voltage and current drawn from the device under test. -
How much does the component bill cost?
The components Bill of Material is below $10. -
What is the maximum voltage the PSU under test can handle?
The PSU under test has a maximum voltage limit of 55V. -
Can the current load be increased beyond 5A?
Yes, the current load can be set to 5A or more by changing the Rs value. -
Does the device include an interface for a PC?
Yes, it features an integrated USB-to-Serial converter and an API for communicating with a PC. -
Where can I find the source files for this project?
All source files can be found on the projects GitHub page. -
How accurate are the current and voltage measurements?
The current and voltage measurement accuracy is below 5%.
