Can this sensor be run at 3.3 volts for compatibility with Arduino 3.3 volt boards (Due, etc.)? Also, is the Gravity digital interface board needed for connection of the sensor to the Arduino or can this sensor be directly connected to the Arduino?
Thanks,
John
Hi,
The Gravity Non-contact Liquid Level Sensor has an operating voltage of 5 ~ 24V. Therefore, it won’t work with a 3.3V Arduino board.
It can be directly connected to a 5V Arduino board. It comes with a 3 pins cable.
Regards,
Thanks for the reply.
In doing a bit of searching, it looks like this sensor is the ‘High Low Level Output Principle’ sensor shown in the schematic below. Doing some testing, it appears that the resistor between Vcc and Out is 20KOhm, so a voltage divider could be created treating this resistor as R1. When I added a 33KOhm resistor (treating this resistor as R2) on the Out wire from the DFRobot digital interface board to GND, the voltage on the Out wire decreased to 3.089 Volts from the sensor supply voltage of 4.963 volts (supplied by the 5.0 Volt pin on the Arduino Due). Thus, it would be compatible with the 3.3 Volt maximum input of the Arduino Due.
Hi,
Thank you for posting this information for other users to use the Gravity Non-contact Liquid Level Sensor with 3.3V microcontrollers.
As a follow-up to the use of this sensor, I found that the sensitivity can be increased beyond that which can be selected on the interface board.
My application required monitoring a 100 gallon HDPE water storage tank for domestic water. The wall thickness of this storage tank was estimated at ~1/2", which was too thick for the sensor to detect a change in water level even at maximum sensitivity.
I had a spare sensor, so I cut off the plastic casing to see how the sensor was constructed and if it could be modified for my application (see photos below). When I saw the copper sensing plate, I thought that perhaps a larger plate area might increase the sensitivity of the device. A 34 mm diameter (2 mm thick) aluminum plate glued to the casing with silicone adhesive worked perfectly, and did not require removal of the plastic casing (see photos below). I use the default sensitivity on the interface board.
My application uses 3 of these sensors applied to the wall of the water storage tank. One at ~80 gallons to indicate a full condition, one at ~60 gallons to indicate the level when a refill will take place, and one at ~40 gallons to indicate an emergency condition such as dry well state. An Arduino Yun Shield + Arduino Due is used monitor the sensors, connect to my home network and send status updates via text message to my iPhone. At present, the system has been up for 19 days and 31 fill cycles.
https://dl.dropboxusercontent.com/u/788548/Sensor1.jpg
https://dl.dropboxusercontent.com/u/788548/Sensor2.jpg
Nice project ! Thank you for sharing the update 
Hi, i am aware you probably already have a solution for your application however i was interested to know if your application requires a continuous level sensor or a point level switch?
These sensors from SST Sensing are solid state optical liquid level switches and have various mounting threads, housing styles available. The best way to mount these sensors is through the wall of a tank/vessel and the sensor tip only has to protrude ever so slightly into the tank.
Have a look here for more info sstsensing.com/product-category/sensors/liquid-level-switches/
I am wanting to know how to incorporate one of these sensors into a system that uses a standard 3 wire infrared sensor would one of these 4 wire sensors with the bored and 3 wire connector be suitable for my application. its an Neptune apex aquarium controller?
This Optomax Digital Liquid Level Switch has 3 wires (Vs, Output, GND) and works with a supply voltage of 4.5VDC to 15.4VDC.
I know you posted this a long time ago, but I want to thank you for sharing this info about increasing the capacitance – and add to it that I merely had to add aluminum tape to the sensor, because it’s more the distance than the thickness of the extra plate that increases sensitivity.
At first, I added tape to the sensor, then tape to the vessel, but this was far too sensitive, so I removed the tape from the vessel, and the one layer did the job for me. I imagine you can adjust this by the size of the patch of tape, if needed.
The aluminum tape is simply some left over aluminum tape used to assemble heating duct. This is not duct tape, but tape that is like aluminum foil that’s sticky - it can be a little sharp to work with, but cuts easily with scissors.
Anyway, I wanted to share my findings so it might also help someone like me coming years later.
