Saltwater
Contact Photoelectric Liquid Level Sensor Module for Arduino & Raspberry Pi
Reviews
4.6/ 5
Brand CQRobot
- 5 stars 11
- 4 stars 1
- 3 stars 0
- 2 stars 0
- 1 star 1
Product description
This is a contact-type photoelectric liquid level sensor module that detects liquid presence by an encapsulated LED emitter and a matching phototransistor. The package contains the probe assembly, the small PCB with an open-collector output stage, a DIP switch for output voltage selection, a silicone sealing gasket at the probe interface, and a short connector cable (commonly a JST to Dupont style) for hooking to controllers.
The sensor has no mechanical float or moving parts. It is designed for low power consumption and high sensitivity, and the materials used (plastic probe housing with a rubber gasket and sealed optical elements) offer corrosion resistance and reasonable chemical and temperature stability. Typical probe diameter is about 20 mm and the probe is molded in plastic with a rubber sealing ring around the sensor face.
A DIP switch on the module selects the logic high output level on the signal lead: set one position for a 5V high or set the alternate position to output a 3.3V high, allowing direct connection to 3.3V microcontrollers without extra level shifters. The module provides an open-collector style signal output for easy interfacing with Arduino, Raspberry Pi, ESP32 and similar boards. The probe can be mounted upright, upside down, sideways or at an angle to monitor horizontal levels, spills, or dry conditions, and it is commonly used for automatic irrigation, aquarium ATOs, plant watering systems, garden and small agricultural monitoring.
Pros
- Selectable 5V/3.3V output via DIP switch
- No moving parts — optical detection reduces mechanical wear
- Small probe fits multiple mounting orientations
Cons
- Not fully watertight at wiring entry — careful installation needed
- Attached cable is short on some units
- Gasket finish can show minor molding flash
VerdictThis contact photoelectric level probe is a straightforward, dependable option for simple liquid-level sensing in DIY automation. It combines a small, sealed probe and a compact PCB with an open-collector output and a DIP switch to select 5V or 3.3V signal levels, so it integrates cleanly with Arduino, Raspberry Pi, ESP32 and similar controllers without extra level shifting. The build quality is g
Reviews
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JulesVerne 5/5
Sturdy and reliable — flexible voltage option
I installed this in a rainwater system with an Arduino Nano and it has been reliable. I potted the electronics in epoxy so I lost the ability to flip the voltage switch later, but having the 5V/3.3V option is useful for matching 3.3V boards like the Pi or ESP32. No false triggers so far from stray drops. PCB quality is very good and the included silicone-jacketed connector cable is high quality. The gasket had some rough flash, but that wasn’t a problem for my epoxy-potted setup.
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Mustafa Aydin 5/5
Handy for small automated water projects
Used this on a cat fountain tied to Home Assistant — when water falls below the set point I get a WhatsApp notification. Works wonderfully in that setup.
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Teo 5/5
Great for Arduino-controlled tanks
These sensors work very well and let me fill and control a reservoir level with an Arduino.
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James Rober Bottino Warren 5/5
Fast to deploy with Raspberry Pi
Did exactly what I needed. With a little free Python code adapted to my needs I had it on a Pi1b above my sump pump sending email alerts within minutes of opening the box. Very quick to go from unboxing to monitoring — I’ll buy more.
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halin 5/5
Simple hookup for ESP32 projects
Worked as expected with my ESP32. No connection or readout issues — straightforward to wire and use. I recommend it.
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Trevor Ross 5/5
High quality and easy to interface
Very pleased — the module is high quality and simple to integrate with controllers.
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Jérémy 1/5
Prone to false triggers from splashes
I used it with an MCU to control draining a tank. When random drops splashed the sensor lens it remained falsely active while the droplet stayed there, causing unintended drains. I switched to a capacitive sensor to avoid that issue.
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Saal 5/5
Automated my large tank refill
I automated a 275-gallon tank fed by dehumidifiers with a Raspberry Pi and this sensor. We hardened the installation for reliability. Note that only the probe tip is waterproof; assembly literature also mentions this.
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finbo 5/5
Works as described — watch the switch setting
Initially I thought it only ran at 5V, but it will operate at 3.3V as long as the DIP switch remains in the correct position. Functions exactly as specified.
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Phillip Dieppa 5/5
Works well but cable needs extension
Using this as a minimum-level sensor paired with another for the maximum level; it triggers the pump on when low and stops when the upper sensor trips. Performance is good, but the cable is very short and I’ll need an extender.
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woejillis 5/5
Good for reef-pi ATO — install carefully
Bought to monitor aquarium top-off with reef-pi; the system detected it immediately and it worked flawlessly. Important: the module is not completely watertight — it has a wet side and a dry side, so plan the installation to keep the electronics dry. The seller was responsive and supportive.
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Jayjay Hunt 4/5
Looks well manufactured but untested
Item appears nicely made but I haven’t assembled it yet, so I can’t confirm operation at this time.
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Familia Pombalina 5/5
Precise, well packaged, with online documentation
High-quality accessory for Arduino or Raspberry projects, nicely protected in a small box and sealed anti-UV bag. There’s no printed manual in the package, but the manufacturer’s website has detailed assembly guides, mounting examples, test schematics and sample code for both Arduino and Raspberry Pi. The sensor uses an encapsulated emitter diode and phototransistor so they don’t contact the liquid directly. The probe is about 20 mm diameter with a plastic housing and a rubber sealing ring.
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