Link dump: Auto-ranging current measuring instrument for IoT devices

With more research, I am beginning to understand more about burden voltage, the difficulty of measuring the dynamic power draw of a circuit with a wide range of current consumption (a few uA all the way to hundreds of mA), as well as the limitations of the LTC4150 coulomb counter in dealing with this.

Here are a list of devices that are designed to do just that, and that are not too expensive (<$200). I hope to acquire one of them to tinker with in the future:

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Update: Line adapter for Ozito Blade Trimmer

Update (Dec 2021): If you access to a 3D printer, I would now recommend this solution , which makes it super easy to replace the trimmer line. I have been using it for a few months now with zero issue.

Cooling mod for the X96 Air

I realized after my Ugoos box died that overheating is a big problem with cheap Android TV boxes. A teardown of the Ugoos box shows that it does not have any heatsink or fan at all! The X96 Air does have a heatsink, but the heatsink is located at the bottom of the casing with no ventilation. In this default configuration, with the ambient room temperature at 25c and playing a 1080p video, I was seeing the CPU temperature at 67c. I drilled a couple of holes at the bottom of the casing. The CPU temperature fell to 59c with the box raised about 2cm with plastic blocks. I retrieved an old 5V laptop fan: Then cut and strip away a spare USB cable: Solder the red and black wires on the fan and the cable: Secure the fan to the bottom of the casing with double-sided tape, then plug the fan into the box's USB connector. Here's a view of the box with some 3D-printed risers installed at the bottom to give the mounted fan sufficient clearance: The CPU now runs at 43c, a huge drop from the ...

Cooling mod for the X96 Air #2

Previously, I added a USB cooling fan to the X96 Air TV box . The problem with this mod is that the fan is always running, and it runs at full speed. Ideally, the fan should kick in only when the CPU temperature is above a certain threshold. It would be even better if there is a way to control the fan speed. Dan McDonald left me a comment pointing to his project on Github . He basically connected the fan to a USB relay that can be controlled by Python script. His project inspired me to make a similar mod that would make use of the spare D1 Mini boards I have lying around. The plan is to hook up the fan to a MOSFET (2N7000) and control it via PWM. Here's the very simple circuit: The code simply reads a single character from the serial port (0 - 9). 0 will turn the fan off, while 1 - 9 will generate a proportional PWM to drive the fan, with 1 being the lowest and 9 being the highest. Here's the Arduino code: #include <Arduino.h> void setup () { Serial . begin ( 9600 ...

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