Moisture sensor jumper wire length - MAX and max sensors per unit.

What is the maximum jumper wire length to the probe from the interface board and what is the maximum length from the interface board to the arduino?

I am trying to do a individual plant watering system checking moisture level and dispensing water only as needed per plant.

I was trying to figure out how long a sensor can run before wireline loss messes it up ie can we go 50' or 100'

Also wondering how many moisture sensors can run with how many water solenoids.

Practically 24 to 48 on a large system is this EASILY possible?

Thank you

George

digger73:
What is the maximum jumper wire length to the probe from the interface board and what is the maximum length from the interface board to the arduino?

I am trying to do a individual plant watering system checking moisture level and dispensing water only as needed per plant.

I was trying to figure out how long a sensor can run before wireline loss messes it up ie can we go 50' or 100'

Also wondering how many moisture sensors can run with how many water solenoids.

Practically 24 to 48 on a large system is this EASILY possible?

Thank you

George

You have not specified which sensors you are using.

So, no one can guess.

So my answer is No, it is not EASY.

Chuck.

Hello we are looking at using

moisture probe sensor

most seem to be a forked probe with 2 wires that go to a module then it has 4 wire connectors that 3 are used on the arduino

http://www.ebay.com/itm/Latest-For-arduino-Soil-Hygrometer-Humidity-Detection-Module-Moisture-Sensor/222164422186?_trksid=p2352135.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3D0f057e6b920d49eeb5d8fd1dc34d0bdb%26pid%3D100338%26rk%3D3%26rkt%3D16%26sd%3D231250853349

This brings up another question in addition, why are nearly all the demos online using the probe's analog pin, wouldnt you want to use a digital pin?

digger73:
Hello we are looking at using

http://www.ebay.com/itm/like/231250853349?lpid=82&chn=ps&ul_noapp=true

moisture probe sensor

Are you going to use the Digital output or the analog one?

Based on what I can guess from looking at their picture, the 'sensor' is just measuring resistance through the soil. Dissolved mineral content will directly affect the readings.

The digital output is controlled by the LM393 comparator. With that 'blue' variable resistor, you could 'tune' the sensor's trip point to compensate for almost any wire length. But, drift will be an issue as the sensor ages.

The analog output is more circumspect. It depends on the resistance returned by the sensor. Most cable you would use should have negligible affect on the readings.

But you do realize, that sensor will corrode over time and change is 'readings'.

Chuck.

I have read that sensors corrode due to galvanic action. I was thinking of turning off the sensor when not needed, trip a external breaker to turn em on a few seconds (or whatever is needed to settle down probe) then take reading and if appropriate power down until next cycle.

And what is the normally expected lifespan of the forked probe in full time use?

probes could be pulled occasionally and replaced, they are cheap enough if needed to.

Do you know if I can go 50+ feet from arduino to circut or if I can go 50' from circut from probe or both?

I was planning on getting Siamese 1/4 tubes, water in one and wire in the other for probe.

Thank you

George

digger73:
I have read that sensors corrode due to galvanic action. I was thinking of turning off the sensor when not needed, trip a external breaker to turn em on a few seconds (or whatever is needed to settle down probe) then take reading and if appropriate power down until next cycle.

And what is the normally expected lifespan of the forked probe in full time use?

probes could be pulled occasionally and replaced, they are cheap enough if needed to.

Do you know if I can go 50+ feet from arduino to circut or if I can go 50' from circut from probe or both?

I was planning on getting Siamese 1/4 tubes, water in one and wire in the other for probe.

Thank you

George

You should minimize the distance from the Arduino to the controller. the 50' wire should be from the probe to the controller.

The service life is highly dependent on your conditions, moisture, soil ph, and salt content. I have no guess.

Chuck.

Im designing a watering system argghh, yeah yet another but I cant find the answer on probe length and what affects communication at say 50’ or 100’ away from a central arduino unit. We live in the Mojave desert of CA and would like to do a xeriscaping of our front yard and water 6 plants with only the exact amount of water they need to stay alive. Would also like to have it log all data to a sd card for later analysis.

searching ebay for moisture probe nano arduino yields several probe kits. All around $1-2
Pic attached below.

I plan on powering my arduino nano (ordered today!) via 12v2a wall wart to pin30 and would like to use the moisture probe in the analog mode 6 of them connected to arduino, to a 12v 8 pack relay, 6 used for water pumps, 1 for power on to the probes (to limit galvanic action ) turn them on before a reading.

Questions

  1. How long can the 2 wire lead be to the probe from the circut
  2. How long can the wire lead be to the arduino from the circut.
  3. can ardunio uno power all 6 probes at once?

probe.jpg

Please supply a link to the device so we can see its specifications.

Weedpharma

I attached a picture earlier. look a that as well.

I thought most all on ebay were the same sorry, here is the link

Are you using analogue or digital output? Digital would be able to be longer cable to Arduino. It also depends on the cable used.

What distances do you want and what cable are you going to use?

They would use only a few mA so you should be able to power 6 sensors.

Weedpharma

Loltageooking at the picture it is most certainly an analog output, and it
is probably consisting of a voltage devider with the probe as one of the
resistors and the trimpot as the other, going to an OP Amp.
In this way the output (amplification) is adjustable so you can compensate for any
wire loss.
So you will be OK by using 100 feet or more even with thin wires.

so 50' is ok from the sensor to the probe, standard guage jumper wire?

digger73:
so 50' is ok from the sensor to the probe, standard guage jumper wire?

I cannot see any problem, unless your environment has a large RF field. Those long wires could act as an antenna.

Stretch out a chunk of wire and measure the voltage across it.

Around here, we have had problems with ground faults, our soil is so dry that we can generate hundreds of volts different between buildings if there is a circuit fault or miss wiring.

I have personally destroyed telecom equipment that ran between two outbuilding only 50 feet apart. In one of the building there was a 5hp motor grinding grain(neutral and Hot were reversed). It had it's neutral bonded to it's frame which was grounded to the building. The buildings earth ground was not bonded to to the electrical grid. My telecom circuit was bonded on both ends. As soon as the Grinder started up. My telecom wire melted down.

So, no guarantees.

Chuck.

100ft of wire will have a lot of stray pickup that will make the signal very noisy and require filtering.

Weedpharma

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