For the National Science Foundation project "SBIR Phase II: A spectroscopic THz Sensor for Mixed Gas Analysis and Air Pollution Monitoring"
Schematic for the arduino shield
Adobe Portable Document Format - 34.47 kB - 06/19/2020 at 18:27
We've figured out how to operate both the solenoid and vacuum pump brushless motor from different pins on the same Arduino shield! The motor can simply turned on or off by supplying 5V from a MOSFET on the Arduino shield.
As for the pressure sensor, we've connected the positive lead to Analog pin 0 and ground to ground. We're using a code which either opens or closes a solenoid depending on whether this voltage on pin A0 is greater or less than 5 volts. When running the system at atmospheric pressure, the solenoid began sputtering wildly. We're not sure what the voltage scale on the pressure sensor is, so we don't know whether we should expect the solenoid to be open or closed at this pressure. We're considering using the serial monitor in Arduino to see what voltage is being supplied from the pressure sensor to the pin at this pressure.
The 12V solenoids have arrived and are operable from my current setup! I've written an arduino code in which the solenoid opens only when a voltage input passes a certain threshold. This means that, when the pressure sensor arrives, the system can be set up such that the voltage output from the sensor can operate the solenoid.
We are also trying to determine whether we can operate multiple arduino shields running different codes from the same arduino UNO board. Both shields use pins in common, so it may not be possible to run code to both at once. Does anyone know whether it might be possible to run two different codes to the shields, if it is done not simultaneously? For example, a code could be run to one shield to open the solenoid, then immediately after, another code could be run to the other shield (which operates a vacuum pump) to pump gas into the chamber? Any thoughts would be appreciated!
I've created an arduino code to switch on and off the solenoid (a modified blink.io code). Right now the board outputs a maximum of 12V, and my Solenoid is 24V so isn't operable by the board. I tested the board on a smaller solenoid, though, and it started opening and closing! I tried wiring two of the arduino shield's output ports in series, but the voltage remained at 12V.
Next steps are to order a 12V solenoid and a pressure sensor, so that the solenoid can be autonomously opened or closed by the arduino depending on the pressure in the chamber. I plan to use a DigiVac Model 276 (BASE) vacuum gauge which includes a thermocouple vacuum gauge combined with a piezo sensor. Any insights on creating an arduino code for operating this system would be appreciated!