Using Phyphox, Bluetooth, and ESP32, many circuit experiments have been conducted, but they have been limited to the realm of direct current because the development board cannot directly collect alternating current signals.
Previously, experiments on Lenz’s law were conducted using Phyphox, Bluetooth, and ESP32 by first preloading a constant direct current in the coil, and then performing the Lenz’s law experiment based on the constant direct current. After receiving the DC signal, Phyphox would subtract the original constant DC, and the difference would be displayed on the mobile phone screen. This design was not only complicated but also inconvenient for students to understand and accept.
Recently, the ADS1115 differential voltage module purchased by the micro-master arrived. Upon receiving the goods, it turned out to be disassembled parts. So, during lunch, I went to the clockwise Rubik’s Cube robot studio of expert Li Lu at the Maker Education Master Studio in Jiaozuo City, where technical staff helped with the soldering.
Under the remote guidance of Teacher Mei Xiaoxuan from Beijing’s Heping Street No. 1 Middle School, the micro-master carefully followed the diagram to connect the circuit step by step. Although the circuit connections were correct, I indeed did not understand the underlying computational principles, feeling that the matter was quite deep. For me, it was not feasible to just feel my way through; I could only hitch a ride on a boat.
After making slight modifications to the source code shared by Teacher Mei from Beijing, I uploaded it to the ESP32. In Phyphox, I added the experiment via Bluetooth, and the experiment’s source code was automatically loaded into the smart phone’s Phyphox.
Establishing a Bluetooth connection between the smartphone and ESP32, I ran the mobile experiment program to measure the voltage across the battery box using the ADS1115; then I swapped the two poles and continued measuring.
After the experiment, I paused the program, expanded the data table to full screen, selected the measurement data, and found that the terminal voltage of the two batteries was actually 3.29 volts. The micro-master was quite puzzled; weren’t the two batteries supposed to have a terminal voltage of 3.0 volts?
The micro-master tried measuring with a newly bought digital multimeter and found it was not 3.0 volts, but rather 3.22 volts.
Suddenly, the micro-master remembered that the terminal voltage of a new battery under no load is greater than 1.5 volts, so the terminal voltage of two batteries should be greater than 3.0 volts.
With this thought, I felt relieved.
Since the combination of Phyphox, ESP32, and ADS1115 can collect alternating current signals, more exploration experiments related to alternating current signals can be designed in the future.
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