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A low-current DC power meter
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"microammeter": a low-current power meter This is a box that uses the TI INA219 high-side current and power monitor to measure low current and voltage usage. This is particularly helpful for doing experiments to minimize power utilitization in battery-powered devices. The custom-built hardware contains the following: - Teensy 3.2 microcontroller from www.pjrc.com - TI INA219B current/power monitor - 4-line by 20-character LCD display - 2-pole 4-position switch to change the shunt resistors and inform the CPU - four pushbutton switches: "start/stop", "clear", "change rate", "export" The display shows: - instaneous voltage, current, and power - average voltage and current since last reset - cumulative current in mAH since last reset - elapsed time since last reset Other features: - The maximum current range can be 1500, 300, 30, or 3ma. - At the 3ma range, the resolution (not the accuracy!) is 0.1 uA. - Samples can be taken 1000, 500, 250, 100, 10, or 1 times per second. - The last 5000 samples can be exported to a PC over a serial port in spreadsheet CSV (comma separated values) format, for graphing or other analysis. This is what the startup screen looks like: L o w - c u r r e n t D C m e t e r V e r s i o n 1 . 0 m a x c u r r e n t : 3 0 0 m A r a t e : 1 0 0 / s e c Here's an example of a running screen: N o w 3 . 4 4 0 V 1 4 . 3 3 2 m A 0 . 0 4 6 W 2 5 . 4 S A v g 3 . 1 9 7 V 1 2 . 5 0 1 m A C u m 0 . 0 8 8 m A H There is a photo of the box in operation and example graphs in this directory.