Continue to Site

Welcome to

Welcome to our site! is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Water Level Sensor (DN-BLC)

Not open for further replies.


Advanced Member level 2
Mar 21, 2015
Reaction score
Trophy points
Activity points
Hi all,
I am trying to crack water level sensor (DN-BLC) which are being used in Washing Machines. I have even gone through the videos of how the sensors works.
The video link shows how the sensor works and gives an output frequency as per the low or high air pressure which makes the change in inductor value inside the sensor.
I have even traced the circuit diagram from one of the PCB. (Circuit Attached). In the circuit diagram the PIN1, PIN2 and PIN3 are the output pins on the Sensor. L1, C1 and C2 are the internal Inductor and capacitors.
The problem is when i created the PCB as per the circuit diagram and tested with the actual sensor, i am not able to get any output frequency on the scope at MCU_PIN.
Can anybody please suggest what can be the issue.
--- Updated ---

I am attaching the sensor image also for your reference.


  • Water Sensor.png
    Water Sensor.png
    38.8 KB · Views: 375
  • Water Sensor1.png
    Water Sensor1.png
    176.3 KB · Views: 193

Don't give up so soon. 'It does not work' is not the end of testing, it is the beginning.

Is power present (not shown in your circuit diagram)?
How did you generate 2.5V? (also not shown in your circuit diagram)
Is the pinning of each component correct (sensor pins 1 and 2 don't match the video)
Did you mount the right inverter chip (there are buffered and unbuffered versions, you should use the right one)

Et cetera

With oscillators sometimes you need to use the unbuffered version of that inverter chip the 4069ub

Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to