Pressure Sensor Wiring

I’m trying to measure the water level in a container that’s 30" tall. I think I have finally found a sensor that will work: BLCR-L30D-U2 but I’m not sure how to connect it to my argon.

right now I’ve got it connected to my argon like this:
Sensor - Argon
Pin1&3 - 3.3V
Pin2 - NC //is this my problem?
Pin4&6 - A1
Pin5 - GND
and I’m getting 2030-2070 on A1
If someone out there can point me in the right direction, I’d sure appreciate it. What I’d really like to learn is what all the pin definitions mean, (VsA, -Vout…)
Or maybe someone has better sensor for the job here.

Hi, I know nothing about these sensors but at first look I noticed this on the datasheet:


So maybe this is not the right sensor?
From a search, seems tallest container could be 30 inches with these sensors.


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I inserted the wrong link. Try this one.
but regardless of the type, it looks like all these sensors pretty much have the same wiring diagram. Wished I could figure out how to hook it up. 0-42mV output

Since the output of that sensor is 0 - 42 mV you’ll probably want an op-amp amplifier.

The Argon ADC measures 0 - 3.3V with a scale of 0 - 4095. In other words, 1.2412 units per mV.

42 mV thus would be a scale from 0 - 52 from analogRead(), which isn’t using much of the available range and is prone to errors. Using an op-amp multiplier will use more of the available ADC range,

When I’ve had to measure the level in a tank I’ve used a magneto-resistive float sensor. Most of them (at least in the United States) are 240 - 33 ohm variable resistance. The design in this app note is for the Tracker One but it would work similarly on the Argon.

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Hi @lsfarm -

I suppose depending on your design you can also use distance sensor? I briefly worked on a POC to measure water level in 5 000l tank (1.8m high) and opted for the use of distance sensor. I am working to finish the sensor design that will function as an add-on for another project I did. I will post this on the forum when done.

I am also not familiar with the BLCR sensor range, so can’t be of much help there sorry. Maybe this article can provide some helpful information?


Thanks for the reply’s @rickkas7 and @friedl_1977! I’m going to have to study that float sensor setup some more, got another project that would work nice on.
I should have added more details for this project. I’m building a tea making vat and it will have ice in it, so once the tank level gets down to about 50% full the tea level is going to drop down below the ice in the tank making any kind of float or radar sensor useless. So the only thing I’ve been able to find that might work is a pressure sensor mounted to the bottom of the tank, but maybe I’ve missed a sensor type that might work for this application?

Ok… I need some help here with op-amps as this is my first go. I’m trying to use the BLCR-L30D-U2 pressure sensor, it outputs 0-42mV I’m going to try connecting it to the argon through a TLC272CP op amp. (DataSheet) The only reason for this op-amp is, is that it’s what I’ve got here in an old electronics kit. Than according to this calculator if I use a 1Ω for Rin and 77Ω for Rf I should get a gain of 73. I’m I headed down the right road at least? or am I way off here? Also would appreciate it if you point out the errors in my wiring: DropBox PDF drawing

Hi @lsfarm -

Wow, this sounds like something nice indeed.

I do not mean to steer you away from your current direction of thinking, so I am only offering my opinion and ideas :slight_smile:

I usually opt for the most simplistic solutions. In your case I would probably work with a small load cell as apposed to a pressure sensor. Mostly because I have work with them a lot (between 0.1kg and 200kg) and they rend to be quite reliable and easy to get working :nerd_face: The challenge you might facing with either pressure sensor and Load cell is the weight of the ice. I am nor sure what accuracy you are hoping to achieve, but it is something you might need to consider in your vat design.

Another way (probably more accurate) would be to have a electrodes inside the vat at i.e 25%, 50%, 75% and 100% . If course these will need to be shielded from the ice in order to only detect the tea. This can be easily achieve by utilising some sort of perforated housing inside the vat, small holes to let tea through but too small for ice to affect the electrodes.

If you do not require extreme accuracy, I would consider load cells.

Sorry, I have not used these before.

Hope this helps in some way :slight_smile:

Kind Regards,

Side note: there are custom configured float level sensors. Standard is 1/4” resolution with 100ohm resistance for every 1/4” step. So for a 30” tank your looking at a range of 0 to 750 ohm (0 ohm at the top of the fitting connection full tank, and 750 ohm at the bottom of the stem when float indicates empty tank). This assumes you connect your magnetic reed switch float level sensor at the top of the tank. Costs around 150-200 USD for full 316SS stainless. Optianally available with 4-20mA output (4mA at top of fitting connection).