Water sensor for Pics.

Started by "Ing. Yosu Izaguirre" December 2, 2008
Hi to all,
My name is Yosu Izaguirre, Im electronic engineer and have one master in automation of controls, but I have a little problem for you to help me...

Im trying to design one water sensor for be read from a one PIC12F675 or PIC16F683, is the same but one have more io pins and another features...

So the fact is that the sensor must be hard worker because must be inside the water for ever and never fail, so I have two circuits thats generate one 2Khz to 4Khz square wave on the output, this square wave is good to me because I can read the period and know if the water is present. My problem is thinking to future because this kind of circuit can generate electrolisys and damage the electrodes probe, so I know that the capacitives probes are good thats why

I NEED HELP TO FIND THE BEST WATER SENSOR CIRCUIT TO DO THIS JOB.

My problem is not with the pic is with the development of the water sensor...

I know about the Microcontrollers PIC since 1998, I can help to the people forum too, for your help I know about the 10f, 12F, 16F, 18F, 24F & 33F PIC microcontroller series, RENESAS mC and Motorolas, but Im the best in Microchip, so anything that can I do for you its ok, so I can comunicate in english 75% and spanish 100%.

Att. Mgs. Ing. Yosu Izaguirre
R&D Engineer

Ingeniero Electrico (Investigaci y Desarrollo).

Caracas, Venezuela.

Tlf.: +58-212-7539435

Cel.: +58-412-9599092

y...@cantv.net
y...@hotmail.com
y...@yahoo.com
Dear Gavin,
 
you have to change polarity with each cycle to resolve the problem of electrolysis by using for example CD4069 so instead of having +5V/0V you will get +5V/-5V.
 
Yours,
 
Amar

--- En date de : Mar 2.12.08, Gavin Dingley a écrit :

De: Gavin Dingley
Objet: Re: [piclist] Water sensor for Pics.
À: p...
Date: Mardi 2 Décembre 2008, 10h09

Hi Yosu,
you could use a an RC oscillator (see: http://www.fairchil dsemi.com/ an/AN/AN- 118.pdf), and replace the capacitor with your sensor. The when the water reaches the sensor the frequency will change, which can be measured by the PIC you are using.
 
The sensor could be two cylinders, each covered with thin insulation, with one inside the other. When the water goes in between them the capacity will change, and so then will the frequency of oscillation.
 
Build the circuit and the sensor and watch what happens on an oscilloscope, then you can see how much the frequency changes.
 
Gavin

--- On Tue, 11/18/08, Ing. Yosu Izaguirre wrote:

From: Ing. Yosu Izaguirre
Subject: [piclist] Water sensor for Pics.
To: piclist@yahoogroups .com
Date: Tuesday, November 18, 2008, 1:48 PM

 
Hi to all,
 
 
My name is Yosu Izaguirre, I´m electronic engineer and have one master in automation of controls, but I have a little problem for you to help me....¡¡
 
I´m trying to design one water sensor for be read from a one PIC12F675 or PIC16F683, is the same but one have more io pins and another features....
 
So the fact is that the sensor must be hard worker because must be inside the water for ever and never fail, so I have two circuits thats generate one  2Khz to 4Khz square wave on the output, this square wave is good to me because I can read the period and know if the water is present. My problem is thinking to future because this kind of circuit can generate electrolisys and damage the electrodes probe, so I know that the capacitives probes are good thats why 
 
I NEED HELP TO FIND THE BEST WATER SENSOR CIRCUIT TO DO THIS JOB. 
 
 
 
My problem is not with the pic is with the development of the water sensor...¡¡
 
I know about the Microcontrollers PIC since 1998, I can help to the people forum too, for your help I know about the 10f, 12F, 16F, 18F, 24F & 33F PIC microcontroller series, RENESAS mC and Motorolas, but I´m the best in Microchip, so anything that can I do for you its ok, so I can comunicate in english 75% and spanish 100%.
 
 

 Att. Mgs. Ing. Yosu Izaguirre
R&D Engineer
 
Ingeniero Electrónico  (Investigació n y Desarrollo). 
 
Caracas, Venezuela.
 
Tlf.: +58-212-7539435
 
Cel.: +58-412-9599092
 

yosuizaguirre@ cantv.netyosupicprog@ hotmail.com

yosupicprog@ yahoo.com
 
I was thinking of the electrodes being coated in a thin layer of insulating material, the electric field would penetrate this, and so will be effected by the presence of another dielectric, such as water, but it would hinder the passage of ions.

Cheers,

Gavin

--- On Sat, 12/6/08, metloug amar wrote:
From: metloug amar
Subject: Re: [piclist] Water sensor for Pics.
To: p...
Date: Saturday, December 6, 2008, 7:08 AM

Dear Gavin,

you have to change polarity with each cycle to resolve the problem of electrolysis by using for example CD4069 so instead of having +5V/0V you will get +5V/-5V.

Yours,

Amar

--- En date de: Mar 2.12.08, Gavin Dingley a rit:

De: Gavin Dingley
Objet: Re: [piclist] Water sensor for Pics.
piclist@yahoogroups .com
Date: Mardi 2 Dembre 2008, 10h09

Hi Yosu,
you could use a an RC oscillator (see: http://www.fairchil dsemi.com/ an/AN/AN- 118.pdf), and replace the capacitor with your sensor. The when the water reaches the sensor the frequency will change, which can be measured by the PIC you are using.

The sensor could be two cylinders, eachcoveredwith thin insulation, with one inside the other. When the water goes in between them the capacity will change, and so then will the frequency of oscillation.

Build the circuit and the sensor and watch what happens on an oscilloscope, then you can see how much the frequency changes.

Gavin

--- On Tue, 11/18/08, Ing. Yosu Izaguirre wrote:

From: Ing. Yosu Izaguirre
Subject: [piclist] Water sensor for Pics.
To: piclist@yahoogroups .com
Date: Tuesday, November 18, 2008, 1:48 PM


Hi to all,


My name is Yosu Izaguirre, Im electronic engineer and have one master in automation of controls, but I have a little problem for you to help me...

Im trying to design one water sensor for be read from a one PIC12F675 or PIC16F683, is the same but one have more io pins and another features...

So the fact is that the sensor must be hard worker because must be inside the water for ever and never fail, so I have two circuits thats generate one 2Khz to 4Khz square wave on the output, this square wave is good to me because I can read the period and know if the water is present. My problem is thinking to future because this kind of circuit can generate electrolisys and damage the electrodes probe, so I know that the capacitives probes are good thats why

I NEED HELP TO FIND THE BEST WATER SENSOR CIRCUIT TO DO THIS JOB.



My problem is not with the pic is with the development of the watersensor...

I knowaboutthe Microcontrollers PIC since 1998, I can help to the people forum too, for your help I know about the 10f, 12F, 16F, 18F, 24F & 33F PIC microcontroller series, RENESAS mC and Motorolas, but Im the best in Microchip, so anything that can I do for you its ok, so Ican comunicatein english 75% and spanish 100%.



Att. Mgs. Ing. Yosu Izaguirre
R&D Engineer

Ingeniero Electrico (Investigacin y Desarrollo).

Caracas, Venezuela.

Tlf.: +58-212-7539435

Cel.: +58-412-9599092


yosuizaguirre@ cantv.netyosupicprog@ hotmail.com

yosupicprog@ yahoo.com
Hi there.

First - can you set your email client to send
messages to mailing lists in plain text, fixed space font?

Most of the water level sensors that I have
designed over the years are AC powered. That is:
they operate from the AC mains.

That makes it VERY easy to make a water level
sensor that has long term reliability.

I generally use a power transformer with either
12Vac or 24Vac secondary. Ground one side of the
secondary. Feed the other side of the secondary
through a resistor to a probe that the water will
touch. The water is usually contained in a metal
(stainless steel) tray or pipe which is grounded.

That AC excitation on the probe pretty much eliminates corrosion.

All that remains is to detect the signal level
change that occurs when the water touches the probe.

For what its worth, one of my early designs
monitors 3 probes using a 12c508. The 3 probes
are set at different levels> the lowest probe is
the emergency shut-off (water level too low), the
other 2 probes are the start fill and stop fill
sensors. Start the water fill when the middle
probe isn't touching water any more, stop the
fill when the water touches the top probe.

Hope this helps.

dwayne
At 06:48 AM 11/18/2008, Ing. Yosu Izaguirre wrote:
>
>Im trying to design one water sensor for be
>read from a one PIC12F675 or PIC16F683, is the
>same but one have more io pins and another features...
--
Dwayne Reid
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
www.trinity-electronics.com
Custom Electronics Design and Manufacturing


to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
> Im trying to design one water sensor

I once did a design based on the cooling effect of water (id could
detect any other liquid too). Sensor was an 1N4148. Pulse a high current
through it for a short time. Then measure the heatup (delta in the
forward voltage for a low current). The heatup *after a short time* is
much less when immersed in liquid.

--

Wouter van Ooijen

-- -------
Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu
More than one way to skin a cat...

I once made a 'finger detector', which would also detect water.
It is essentially an 'open' capacitor made of 2 pads on a PCB without GP.
Pads are about 6x6mm and 1mm apart.

Run a 5VPP squarewave with short Tr/Tf (from PIC port pin) to one pad,
The other pad goes to the input pin which must be ESD protected with diodes
and pulled low trough a 1M resistor.

Now simply drive the output High, and in the next instruction test the
input and see
if it is also High, if it is the detector is activated.
Obviously the capacitor is very small and the input must be checked
within uSs.

It worked great, it was able to detect a hand up to 15cm away, and a
finger about 3cm away.

It is the same principal as Bang & Olufsen use in their Beocenter 9000
where all the touchbuttons
are hidden under 5mm glass.


Wouter van Ooijen skrev:
>
> > Im trying to design one water sensor
>
> I once did a design based on the cooling effect of water (id could
> detect any other liquid too). Sensor was an 1N4148. Pulse a high current
> through it for a short time. Then measure the heatup (delta in the
> forward voltage for a low current). The heatup *after a short time* is
> much less when immersed in liquid.
>
> --
>
> Wouter van Ooijen
>
> -- -------
> Van Ooijen Technische Informatica: www.voti.nl
> consultancy, development, PICmicro products
> docent Hogeschool van Utrecht: www.voti.nl/hvu
>
>

--
*******************************************
VISIT MY HOME PAGE:

LAST UPDATED: 23/08/2003
*******************************************
Regards
Eirik Karlsen
To avoid electrolysis you could leave the sensor off most of the
time, just sample peridically. You could turn it on with a solid
state relay, I have used this one from Clare:

http://www.clare.com/home/pdfs.nsf/www/CPC1017N_R05.pdf/
$file/CPC1017N_R05.pdf

BP
--- In p..., "Ing. Yosu Izaguirre"
wrote:
>
>
> Hi to all,
>
>
> My name is Yosu Izaguirre, Im electronic engineer and have one
master in automation of controls, but I have a little problem for you
to help me...
>
> Im trying to design one water sensor for be read from a one
PIC12F675 or PIC16F683, is the same but one have more io pins and
another features...
>
> So the fact is that the sensor must be hard worker because must be
inside the water for ever and never fail, so I have two circuits
thats generate one 2Khz to 4Khz square wave on the output, this
square wave is good to me because I can read the period and know if
the water is present. My problem is thinking to future because this
kind of circuit can generate electrolisys and damage the electrodes
probe, so I know that the capacitives probes are good thats why
>
> I NEED HELP TO FIND THE BEST WATER SENSOR CIRCUIT TO DO THIS JOB.
>
>
>
> My problem is not with the pic is with the development of the water
sensor...
>
> I know about the Microcontrollers PIC since 1998, I can help to the
people forum too, for your help I know about the 10f, 12F, 16F, 18F,
24F & 33F PIC microcontroller series, RENESAS mC and Motorolas, but
Im the best in Microchip, so anything that can I do for you its ok,
so I can comunicate in english 75% and spanish 100%.
>
>
>
> Att. Mgs. Ing. Yosu Izaguirre
> R&D Engineer
>
> Ingeniero Electrico (Investigaci y Desarrollo).
>
> Caracas, Venezuela.
>
> Tlf.: +58-212-7539435
>
> Cel.: +58-412-9599092
>
> yosuizaguirre@...
> yosupicprog@...
> yosupicprog@...
>



to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
Hi Eirik Karlsen,

Thnaks for all your help, you are so helpful for me.... but, do you have some pictures by this: Run a 5VPP squarewave with short Tr/Tf (from PIC port pin) to one pad,
The other pad goes to the input pin which must be ESD protected with diodes and pulled low trough a 1M resistor.

Thanks a lot, I waiting your response..

Att. Mgs. Ing. Yosu Izaguirre

Ingeniero Electrico (Investigaci y Desarrollo).

Caracas, Venezuela.

Tlf.: +58-212-7539435

Cel.: +58-412-9599092
----- Original Message -----
From: Eirik Karlsen
To: p...
Sent: Sunday, December 21, 2008 7:13 AM
Subject: Re: [piclist] Water sensor for Pics.
More than one way to skin a cat...

I once made a 'finger detector', which would also detect water.
It is essentially an 'open' capacitor made of 2 pads on a PCB without GP.
Pads are about 6x6mm and 1mm apart.

Run a 5VPP squarewave with short Tr/Tf (from PIC port pin) to one pad,
The other pad goes to the input pin which must be ESD protected with diodes
and pulled low trough a 1M resistor.

Now simply drive the output High, and in the next instruction test the input and see
if it is also High, if it is the detector is activated.
Obviously the capacitor is very small and the input must be checked within uSs.

It worked great, it was able to detect a hand up to 15cm away, and a finger about 3cm away.

It is the same principal as Bang & Olufsen use in their Beocenter 9000 where all the touchbuttons
are hidden under 5mm glass.


Wouter van Ooijen skrev:

> Im trying to design one water sensor

I once did a design based on the cooling effect of water (id could
detect any other liquid too). Sensor was an 1N4148. Pulse a high current
through it for a short time. Then measure the heatup (delta in the
forward voltage for a low current). The heatup *after a short time* is
much less when immersed in liquid.

--

Wouter van Ooijen

-- -------
Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu

--
*******************************************
VISIT MY HOME PAGE:

LAST UPDATED: 23/08/2003
*******************************************
Regards
Eirik Karlsen
Hi,
see schematics and descriptions here:


Ing. Yosu Izaguirre skrev:
>
>
> Hi Eirik Karlsen,
>
> Thnaks for all your help, you are so helpful for me.... but, do you
> have some pictures by this: Run a 5VPP squarewave with short Tr/Tf
> (from PIC port pin) to one pad,
> The other pad goes to the input pin which must be ESD protected with
> diodes and pulled low trough a 1M resistor.
>
> Thanks a lot, I waiting your response..
>
>
>
>
>
> Att. Mgs. Ing. Yosu Izaguirre
>
> Ingeniero Electrico (Investigaci y Desarrollo).
>
> Caracas, Venezuela.
>
> Tlf.: +58-212-7539435
>
> Cel.: +58-412-9599092

--
*******************************************
VISIT MY HOME PAGE:

LAST UPDATED: 23/08/2003
*******************************************
Regards
Eirik Karlsen