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Author Topic: The effects of Electrolysis in water and how to minimize this effect?  (Read 2152 times)
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Hi all,

I need to build a sensor to see the water level in a tank that have plants(hidroponics). I don't want to use an Arduino for this sensor project. I just need to flash a led when the wires are not any more in contact with the water. This is possible to do without an Arduino?

I have this cheap sensor in mind:


1 - I will incur in problems with Electrolysis and plants(I know that this is not an electronics question. If you don't know, please ignore this question)

2 - How can I minimize the Electrolysis effect in the wires to not dissolve the wires?


Best Regards,
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You need to reverse the polarity on the detection wires periodically (several times per second ?)  In effect you apply AC to the detection wires.   This can be achieved in a DC circuit by setting one probe to 1/2 the supply voltage then switching the other probe between supply voltage and ground.
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Sounds like a job for a pressure switch or float switch to me.  If you simply want to replace the water that is evaporated you don't need electronics.  Think 'toilet'.
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You need to reverse the polarity on the detection wires periodically (several times per second ?)  In effect you apply AC to the detection wires.   This can be achieved in a DC circuit by setting one probe to 1/2 the supply voltage then switching the other probe between supply voltage and ground.

Hi. Thanks for the reply. Do you have some schematic of this or can help me to find one similar?

Best Regards,
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Sounds like a job for a pressure switch or float switch to me.  If you simply want to replace the water that is evaporated you don't need electronics.  Think 'toilet'.

Hi, thanks for the reply.

 I know there is much better options. But I need a very very cheap one.
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Sounds like a job for a pressure switch or float switch to me.  If you simply want to replace the water that is evaporated you don't need electronics.  Think 'toilet'.

Hi, thanks for the reply.

 I know there is much better options. But I need a very very cheap one.
A float valve at about £7.50, or less, in the UK (approximately $12) is surely cheaper than using an Arduino?
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Sounds like a job for a pressure switch or float switch to me.  If you simply want to replace the water that is evaporated you don't need electronics.  Think 'toilet'.

Hi, thanks for the reply.

 I know there is much better options. But I need a very very cheap one.
A float valve at about £7.50, or less, in the UK (approximately $12) is surely cheaper than using an Arduino?

Hi tack. My idea is to do that kind of circuit without using an Arduino.
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I remember from a long time ago, at school there was an experiment to create oxygen and hydrogen.
A piece of carbon was used, but i forgot why.
So maybe you can have a try at this:
Use pencil refill, connect your wires to that and put the pencil refill in the water.
Test it before you use it in the actual situation, to see what the pencil does.
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Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

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A piece of carbon was used, but i forgot why.


Because when you use a metal anode you will slowly dissolve the anode.  Think of electroplating.  But graphite won't oxidize to anything soluble and your graphite rod is not going to corrode away as you apply current.
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Stainless steel might be good for electrodes. Dollar stores often have stainless cooking utensils that might be used for a stainless source.
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Use a really low voltage?
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@Delta_G:
That's what i guessed and why i told about it.
So using the graphite could be an answer to question 2.
But you need to consider the resistance of that pencil refill.
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Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

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If you use a low voltage you won't trigger most electrochemical reactions - it takes several volts to split water
efficiently, so something like 0.1V AC would really cut down unwanted electrolysis.

Unfortunately the resistivity of fresh water varies a lot depending on the amount of disolved ions (so hard
and soft water differ substatially) - you might want a different electrode geometry for soft / de-ionised water
to get enough current flow to be easily measurable.

Another approach would be a capacitive sensor, all water has a high dielectric constant (about 80) and this would be
a non-contact method not dependent on the water's resistivity nearly so much.  There are simple capacitive circuits
where one of the electrodes is connected to an analog input, and grounded via a very high value resistor (100M say).

You set the pin as output, set it HIGH, then switch back to an input and time how long it takes for the charge to
leak away (you can try analogRead() or digitalRead() - for a simple on-off sensor the latter would be adequate).
The more capacitance on the pin the slower the charge will leak away (because there was more charge to start with).
A second grounded insulated electrode forms the other capacitor plate.
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We have an other thread talk about water level measurement;-

The method is discussed at thread:

Ultrasound
Pressure sensor
X band Proximity Sensor
Ku band Proximity Sensor
K band Proximity Sensor
Sound
315MHz/433MHz rf-link Arduino (radio waves blocked by water)
Bluetooth Proximity Sensor
VLF radio waves (3–30 kHz) (radio waves through by water)
Laser-based water level sensor
Capacitance  proximity sensor
Resistance proximity sensor
Measurement the pump discharge pressure (if there is pump)
Float switch

http://arduino.cc/forum/index.php/topic,160378.0.html
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I need to build a sensor to see the water level in a tank that have plants(hidroponics). I don't want to use an Arduino for this sensor project.

This one might do the trick.

SIMPLE WATER LEVEL ALARM CIRCUIT USING IC 555 TIMER



WATER LEVEL ALARM CIRCUIT
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