![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/bca41c85bbc16a007b23558d6a1a28bf.png)
Background
On a hot summer day, nothing better than drinking an ice-cold glass of lemonade when you’ve been playing in the heat for several hours. We know that a fresh lemon itself doesn’t taste quite the same as it does when you mix it with sugar and water, but, how sour is a lemon exactly? Well, the face below may tell the truth. Just kidding! Never try that on your kids. As a maker, I choose to figure it out scientifically---detect its pH.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/c3cf2d4024b57b9857323a731133b4f1.png)
(Image from Mashed.com)
Design Idea
This pH sensor I just got from DFRobot has a lab-grade probe with measurement accuracy of ±0.1 at 25℃, which is perfect for my project. Also, I want the sensor readings to be showed on a screen. Since lately I’ve been trying a new Transparent Display from DFRobot, I decided to use it for data display here. Besides, a RGB LED strip is used to indicate pH values with different colors according to the pH vs Color table. Put all hardware into a cool shell, and start detecting!
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/d52228694e1eea6a494893f25a076ed5.png)
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/6d86e61a16a4a45e80a15fd6fcba7877.png)
The transparent screen will display the pH of the object detected and a pH-vs-Time Chart.
Hardware Connection
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/d8e1059165bc7d1844666544a5d4ea51.png)
pH Adapter (to) ESP32-C3
pH Probe (to) pH Adapter
Transparent Display (to) Display Adapter
Display Adapter (to) ESP32-C3
RGB LED Strip (to) ESP32-C3
3.7V Battery (to) ESP32-C3
Assembly
1. Drill a hole on the front side of the shell to install power switch
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/eb17cb927e6cdffbb1f36fd9ce5adf99.jpg)
2. Drill a hole at the bottom of the shell for connecting the pH sensor cable.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/fa3df7477c81735790479b250c21a693.jpg)
3. Pass the pH adapter connector through the hole and fix it.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/fb1ece2b896549d675fdcfd2ad69569c.jpg)
4. Place the transparent display into the shell window, put a thin plastic film onto it and apply some hot melt adhesive to the edges.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/445d551683f0f723af84111cc6c2f716.jpg)
5. Connect the transparent display to the display adapter, and connect the adapter to the C3 converter board.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/284f76856faf5db93712bfcb131f1dd6.jpg)
6. Fix the C3 converter on the case. Solder wires for connecting the pH adapter, battery and RGB strip on it.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/2e6929805f7d0c155f89ad168d16fce0.jpg)
7. Plug ESP32-C3 onto the converter board.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/0ac655335fd8295f8d43c938910d78e1.jpg)
8. Connect a 3.7V lithium battery.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/bae2fe604c820c610fc12abd063105b8.jpg)
9. Drill three holes at the top of the shell for RGB LED strip.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/2893e7260f7bc0203cc779bcc662712a.jpg)
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/0627f0291105d897bc822abfbce3b41b.jpg)
Oops! Two LEDs broken. Replace them with new ones.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/c89b2f72ce01570873ba761a3655ce96.jpg)
Eh, the lighting effect disappointed me and the transparent display is not transparent.
Redesign a structure to let the content on the transparent display can be viewed on both sides.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/9efcb1fe359116051b477131b653b244.png)
Cut the acrylic plates with laser.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/7b1da1d009330b1979151761d739914f.jpg)
Cut a square on the back cover and fix the acrylic plates onto them as shown below.
Be careful when using laser cutting machine.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/d41000cdc550d13731000d7f207a944d.jpg)
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/0f52ca8342f543de704746cf8632db2d.jpg)
Organize the wire and hardware inside the shell, and put the back cover lid on the shell.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/d7b2a4a616fde45e01d4f99c5512da23.jpg)
Stick some black sticky paper on the shell to beautify it.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/aca066983d02a0e01428693af77d96b8.jpg)
Connect the pH probe to it.
![projectImage](https://dfimg.dfrobot.com/5d3c06d50ad96a3f659ed74c/makelog/74d8816254f0ccc2eafa5ac8e3303388.jpg)
Then all done.
The pH of the lemon detected is 2.3, which is quite sour. And I also detected several other stuff.
The article was first published in dfrobot.com.cn, 2022/06/30
URL: https://mc.dfrobot.com.cn/thread-313523-1-1.html
Author:派大星ym
![licensBg](/images/license_bg.png)