Hi folks,
I'm having problem modifying some components to work together to operate properly.
I'll start with the 5V NPN contactless water level sensor.

It works great, however it outputs 5V when water is detected, so the mini relay that it's driving is on most of the time and I don't think that this is that great for the relay life expectancy. There is 2 of them, one for high and one for low level detection.
I'm looking for solution to invert the output to 0V when water level is detected, or even better to eliminate these relays and connect the sensor output directly to the controller below.

These relays switch inputs on 5V water level controller based on NE555 IC. This controller has 3 submerged probes ( just wires) and it controls the pump. The common probe terminal (A) is not connected directly to the positive or negative 5V of the controller.


I can't use the exposed wires to detect the level so I'm looking for reliable solution how to combine these two components together.

Any help would be appreciated.

 

More thoughts I did not managed to squeeze in within the 10min edit period
I did try to connect the sensor direct to the B/C terminals - did not work
Here is how the sensor board looks

 

Any help would be appreciated.

If you have a volt meter we can check the levels on the A,B and C terminals. The water sensor you listed appears to pull the black wire to ground so this might work with that relay module.
Post a link or part number of that relay module.

 

If you have a volt meter we can check the levels on the A,B and C terminals. The water sensor you listed appears to pull the black wire to ground so this might work with that relay module.

Thanks for reply!
Yes, will measure and post voltages. Controller powered on, no sensors connected. In this state the pump relay is ON.
Left measured positive to each terminal for probe, right negative to probe terminals.




It works fine with mini relays (40mA draw each relay directly connected the sensor)

 

I think all you need is a different relay module that will accept either a high or low signal trigger like this 5 volt unit.
HiLetgo 2pcs 5V One Channel Relay Module Relay Switch with OPTO Isolation High Low Level Trigger
7.39 at Amazon.

 

I think all you need is a different relay module that will accept either a high or low signal trigger like this 5 volt unit.
View attachment 287755

Yeah, that will increase the package size tremendously
I'm looking for something basic or ideally eliminating those 2 relays powered by sensors all together.

 

Yeah, that will increase the package size tremendously

These relay module I listed will replace the modules you have now. The sensors connect directly.

 

These relay modules will replace the modules you have now. The sensors connect directly.

Are you sure? I think these will just turn on or off with the option to set the jumper on 0V or 5V trigger.
The controller I'm using now will turn on the main relay when water drops below the Low sensor, and will stay on till the water level reaches the High sensor, then it will turn off the relay and wait till it drops all the way down again.

 

Then what is the problem if it's working as you say?
Show how you have that black relay wired.

 

Then what is the problem if it's working as you say?
Show how you have that black relay wired.

It's working fine, my "problem" is that the relays need to be there, or do they?
Problem no2 is that they have power on the coit 99.9% of the time since those sensors give 5V output when the detect water.
Not the greatest for power use ( not the main concern) but reliability.
I can't use the other relay contact since if that circuit would fail (no power) the pump would flood everything.

So ideal solution would be to drive the controller input direct without relay or revert the sensor output to 0V when water is detected.

 

So ideal solution would be to drive the controller input direct without relay or revert the sensor output to 0V when water is detected.

From what I'm seeing the output from the sensor is zero when water is detected from the schematic of the sensor.

 

From what I'm seeing the output from the sensor is zero when water is detected from the schematic of the sensor.

No, the relay is on when water level reaches the sensor.
Positive 5V is connected to the relay and the sensor will connect the ground when it detects water.
Tried the opposite way but the relay will not turn on.

 

Correct but the sensor output is actually 0 volts.

 

Correct but the sensor output is actually 0 volts.
View attachment 287765

Well, , yes, that's correct, it will ground the relay and complete the circuit.
I guess I did not explain it in proper terms.
So I need to reverse that and have no power on the relay when there is water detected.
I presume transistor can do that. I tried but failed miserably

I'm sure someone can figure out how to eliminate those 2 relays together but I understand without the controller diagram that is not easy.
There is plenty of examples I found but not sure if they match exactly the one I have. Most of those I found are using positive as common for those 2 probes in the tank.

 

Here is one more circuit but once again common positive probe in the tank.

 

There is a way with the 555 chip. I'm not home presently but it can be rewired as required

 

There is a way with the 555 chip. I'm not home presently but it can be rewired as required

That would be great!
I tried to map the board but with all those small smt components it's not easy.
I posted some voltages in the 2nd post but I can measure anything else needed.
Thank you very much for your time!

 

What is the part number of the 8 pin IC on the relay board that you show in post #. If iy is a comparator then it may be possible to modify the board to give reversed operation.

Les.

 

Try this arrangement.
When the tank is full both sensor outputs are low and so is the output from the 555. When the water level drops below the bottom sensor both sensor outputs will be high triggering the 555 output high.
D1 and R1 form a latch function to keep the output on the 555 high as the water level rises and the bottom sensor goes low again.
When the water level rises to the top sensor the low output will reset the 555.

 

What is the part number of the 8 pin IC on the relay board that you show in post #. If iy is a comparator then it may be possible to modify the board to give reversed operation.

Les.

It's NE555
That main board controller is working perfect, no water relay is on, watter detected relay is off.
I need to figure out the probe side of things.