There are many cases where adding a digital isolator module does not benefit the measurements accuracy. For instance when samples are measured in a beaker, or measurements are made directly in a pool, or in volumes with no working electrical appliances, or when the HomeLab-pH module is battery operated. In these cases measuring with HomeLab-pH alone will suffice and give unaltered pH-values. To purchase HomeLab-pH module alone please visit:
https://www.ebay.com/itm/142423993924
If instead only the isolater module is needed visit:
https://www.ebay.com/itm/142982309889
The HomeLab-pH module is just a measuring block. It has to be assisted by an external CPU-board and corresponding software to perform the calculations. Software packages for Raspberry Pi computer, Arduino controller and ESP8266 modules are freely available to download from the HomeLab-pH companion site at homelab.link. They give the user interface to log and visualize the measured values, as well as to calibrate the board.
When connected to Arduino the module can be controlled by the user visually at the console. Alternatively it can act as a data server for HomeLab-pH accessed by a remote machine through a special communication protocol. The user may program additional functionality using the available HomeLab_pH library for Arduino IDE.
When connected to Raspberry Pi or ESP8266 viewing the readings or calibrating is as simple as pointing a smart-phone browser to the Pi's / ESP8266 's LAN address. The module can also be accessed through requests over http.
Features
Board
- Accurate and stable voltage reading ensures a resolution of 0.01 pH over the 0 – 14 pH range.
- Wide input voltage range suitable also for ORP measurements.
- A digital temperature sensor to compensate pH for temperature impact (ATC).
- Socket with Raspberry Pi compliant pinout.
- A LED and a button for user interaction.
- Supported by free software for Raspberry Pi, Arduino or ESP8266.
- Each board is tuned and tested.
Software for ESP8266
- Browser interfaces to view the measured data, calibrate the system and set WiFi and connection settings.
- Connect as station or access point.
- Data may be shown on an eventually wired small display.
- Temporary unavailable - MQTT support with options also settable via the web user interface. Ready for ThingSpeak MQTT Device.
- Data may also be accessed by separate HTTP calls.
- Calibration
with many options - temperature compensated data for 13 buffer
solutions and an option to use the sensor’s isopotential data.
The ESP8266 software page: http://homelab.link/ph/meter/software/esp8266/
Software options for Arduino
- A library for Arduino IDE.
- Simple visual interface to read and calibrate the module.
- Remote access by means of a special protocol (read and calibrate).
The Arduino software page: http://homelab.link/ph/meter/software/arduino/
Software for Raspberry Pi
- Rich visual interface for module calibration and data viewing, logging and management.
- Periodic unassisted measurements.
- Access to the measured data remotely via an http call or locally at the OS console.
Visual interface for Raspberry Pi
- Simultaneous visualization of pH, temperature and voltage values.
- Accessible from every device with an installed browser.
- Manage, list and plot data from periodic unassisted measurements or points at user choice.
- Calibration with many options - temperature compensated data for 13 buffer solutions and an option to use the sensor’s isopotential data.
The Raspberry Pi software page: http://homelab.link/ph/meter/software/rpi/
Board specification
input voltage range: -900 mV ÷ 2048 mV
supply voltage: 3.3 to 5 V
measured voltage inaccuracy: max 0.1% (but not less than 0.13 mV)
pH inaccuracy*: (temperature adjusted)
pH 4 to 10: not more than 0.03 pH
pH 2 to 12: not more than 0.05 pH
overall dimensions, W:H:D: 59 : 37 : 36 mm (2.3 : 1.5 : 1.4 in)
board dimensions, W:D: 56 : 20 mm (2.20 : 0.79 in)
* The inaccuracy of the measurement depends on the precision of the performed calibration. The specified value is valid for 2-point calibration where the buffers' inaccuracy is not greater than 0.02 pH units and their temperature difference with the sample is less than 5°C. If calibration buffers of ± 0.01 pH are used, the inaccuracy of the measured pH value may be even lower.
Temperature sensor
response time at 90%: typical less than 10 s, max 20 s (stirred water)
inaccuracy: not more than 0.5°C ( 0.9°F )
working range: 0 ÷ 80°C (32÷ 176°F)
tip diameter: ø 6 mm
cable length: about 1 m ( 3'3" ); easily extendable by PS/2 M/F extension cable
What is in the box?
(shown at one of the pictures above)
- A HomeLab-pH circuit board
- A HomeLab isolator circuit board
- A digital temperature sensor
- A mounting set of:
4 screws (M2.5) and a nut
3 spacers – 2x12 mm and 1x25 mm. - A leaflet containing mounting and usage instructions
Attention: a combination pH-probe is not included.