DIY Bluetooth Voltmeter/Ammeter

Build you own DIY Bluetooth combined voltmeter and ammeter. It communicates via Bluetooth with the phyphox app - a free Physics app from RWTH Aachen University. The device is based around a ESP32 microcontroller board and uses an INA219 chip to measure current and a seperate ADS1015 ADC with potential divider onboard for potential difference. This device is capable of simultaeously measuring those quantities and plotting them against time and/or each other. Resolution of 1mA and 10mV respectively with a range of 0-3.2A and 0-18V. Data rate of ~100Hz.

• I/V characteristics
• Capacitor charge/discharge
• Faraday's Law

Full build guide with code here: https://github.com/RGill-1/Bluetooth-Science-Sensors/wiki/5.-Volt-Ammeter

Case Features:

• Snap fit lid
• Push button to put ESP32 into deep sleep
• RGB LED for status
• Space for 500mAh battery
• Single box of M2.5 hardware required (Adafruit 3299)

I have had success printing with 0.20mm layer height.

Use of threaded inserts is optional. If you do not want to screw down the lid leave the insert holes empty and choose the lid with no holes in it - will still snap fit.

STEM Project

This is part of a series of devices all based on the same Adafruit ESP32 Feather V2. Making use of the QT STEMMA cable system to be as solder free as possible - allowing you to hot swap boards / sensors as needed. Follow these Printables links to the:

• Light sensor - https://www.printables.com/model/385964-diy-bluetooth-light-sensor
• Load Cell Force sensor 
• Distance sensor - https://www.printables.com/model/391840-diy-bluetooth-distance-sensor

The aim is to work with students to develop these sensors (and others like them) as part of an extra-curricular STEM club. The students will learn how to:

• Conceive different sensors / combinations of sensors to achieve scientific goals
• Use CAD software to design cases
• Slice and 3D print the cases
• Use Arduino to code the devices such that they communicate with the phyphox app to plot the data. The app allows for the creation of custom experiment views which the students can configure.

Any feedback much appreciated.