salt tester detector

[Courageous]

I really want to know the exact components for building a salt tester detector.
Please urgent answer needed.
Thanks

 

[ronsimpson]

Where ever you found this schematic there should have been a list of parts.
It looks like a device for measuring the resistance of water.
I think you will get the same information from a ohm meter and two probes in water.
Do you have a volt/ohm meter?

 

[Courageous]

Below are the list of items as stated in the site where I got the schematic but not so specific
arts:
R1 470R 1/4W Resistor
R2,R5 10K 1/4W Resistors
R3,R6 220K 1/4W Resistors
R4 5K 1/2W Trimmer Cermet
R7 680R 1/4W Resistor
R8 2K2 1/4W Resistor
R9,R10,R11,R12,R13 1K 1/4W Resistors
C1 100µF 25V Electrolytic Capacitor
D1,D2,D3 3 or 5mm. Red LEDs
D4 3 or 5mm. Green LED
D5 3 or 5mm. Yellow LED
IC1 LM324 Low Power Quad Op-amp
P1 SPST Pushbutton
Probes
B1 9V PP3 Battery
Clip for PP3 Battery

Please should you have any idea pls share with me

 

[Reloadron]

The parts list is pretty specific, how specific do you want it to be. That parts list is about all you need, as is for that circuit.

The circuit is a very crude circuit for measuring the conductivity of a solution, like water. Pure water has a very high resistance thus low conductivity, salt water, depending on the salt concentration has a very low resistance and a high conductivity. Unless that unit is set up and calibrated against know saline concentrations it means nothing. What? Salt, Saltier and Saltiest? That is about all it does. It isn't a true conductivity meter in any sense of the word. The circuit concept is pretty straight forward and simple. What exactly are you trying to measure? The conductivity of water with salt in it? Exactly means just that, exactly.

Ron

 

[ramuna]

Hi,
I agree with Ron, the parts list is complete and sufficient to construct the circuit. Incidentally, I found the site that the OP presumably got the circuit from:
**broken link removed**

 

[Reloadron]

Thinking about this and thanks ramuna for the link I would think about building a 10 LED version around a LM3914. Should give much more resolution and a lower parts count other than having more LEDs of course. I see in the link they do make a saline solution to sort of calibrate the unit, not great but not bad. I would start with distilled water rather than tap water.

Ron

 

[audioguru]

My tap water comes from a fresh water lake with no salt in it. But it has a LOW RESISTANCE! Pure distilled water has a high resistance.

 

[Reloadron]

My tap water comes from a fresh water lake with no salt in it. But it has a LOW RESISTANCE! Pure distilled water has a high resistance.

Enter the real problems. While circuits like the circuit posted actually do something (we all enjoy watching LEDs light) they are far from accurate devices for actually measuring true saline or salt content of water. Audioguru gets his fresh drinking water from a lake in beautiful Canada. A nice clean fresh water lake. Yet, even though the water does not contain salt it does contain other dissolved solids resulting in the water having a low resistance or high conductivity. Resistance and conductivity are reciprocals. Setting aside the solution for a moment the linked article mentions:

Set R4 to obtain a zero reading on the voltmeter when the probe is immersed in fresh water.

This is where high quality or distilled water should be used or even pure deionized water. You need a good baseline to start from.

The SI unit of conductivity is S/m and, unless otherwise qualified, it refers to 25 °C. Often encountered in industry is the traditional unit of μS/cm. 106 μS/cm = 103 mS/cm = 1 S/cm. The numbers in μS/cm are higher than those in μS/m by a factor of 100 (i.e., 1 μS/cm = 100 μS/m). Occasionally a unit of "EC" (electrical conductivity) is found on scales of instruments: 1 EC = 1 mS/cm. Sometimes encountered is a so-called mho (reciprocal of ohm): 1 mho/m = 1 S/m. Historically, mhos antedate Siemens by many decades; good vacuum-tube testers, for instance, gave transconductance readings in micromhos.

The commonly used standard cell has a width of 1 cm, and thus for very pure water in equilibrium with air would have a resistance of about 106 ohm, known as a megohm, occasionally spelled as "megaohm".[3] Ultra-pure water could achieve 18 megohms or more. Thus in the past megohm-cm was used, sometimes abbreviated to "megohm". Sometimes, a conductivity is given just in "microSiemens" (omitting the distance term in the unit). While this is an error, it can often be assumed to be equal to the traditional μS/cm.

The conversion of conductivity to the total dissolved solids depends on the chemical composition of the sample and can vary between 0.54 and 0.96. Typically, the conversion is done assuming that the solid is sodium chloride, i.e., 1 μS/cm is then equivalent to about 0.64 mg of NaCl per kg of water.

Molar conductivity has the SI unit S m2 mol−1. Older publications use the unit Ω−1 cm2 mol−1.

There are several key variables here things like the area of the probes and he probe spacing. So while little circuits like this can be amusing and educational They are far from accurate measuring devices and should be treated as such. Here in Cleveland, Ohio my tap water, fresh water, drinking water or whatever we choose to call it is drawn from a crip about 5 miles out in Lake Erie off the Cleveland coastline. It's fresh water but low resistance and high conductivity. No salts but who knows what dissolved solids. Even if I add salt to increase the conductivity I really don't know how that salt is reacting with whatever dissolved solids are already in the water, things like chlorine or fluorides. Truth is unless I know my exact concentration of added salt and exactly what water I start with I really get back to salty, saltier and saltiest.

Ron

 

[atferrari]

I am used to deal with fresh, brackish and sea water depending of the percentage of salt and measure its density.

My question is: what kind of salt is the OP talking about?

Had I to deal with this I would like to know that first and then make sure the influence each type of "salt" has in the problem to solve.

Ask any chemist what salt is. You could spend many hours listening his answer.

 

[Reloadron]

I am used to deal with fresh, brackish and sea water depending of the percentage of salt and measure its density.

My question is: what kind of salt is the OP talking about?

Had I to deal with this I would like to know that first and then make sure the influence each type of "salt" has in the problem to solve.

Ask any chemist what salt is. You could spend many hours listening his answer.

Well taken from the link that ramuna was kind enough to provide:

Device purpose:

This circuit was designed to detect the approximate percentage of salt contained in a liquid. After careful setting it can be useful to persons needing a quick, rough indication of the salt content in liquid foods for diet purposes etc.

My best guess would be common table salt NaCl equal parts sodium and chlorine. However, yeah, simply saying salt does leave much to be desired, especially if you get a chemist going. For example a very convenient method to calibrate humidity sensors is the use of saturated salt solutions. There are dozens of them and all salt or chlorides. The coastal areas of the US much like where you are have hundreds of rivers flowing into the oceans and like you I can go from a fresh water river to brackish water where river meets ocean to salt water where we are beyond the brackish mix and into the ocean. Even then, different oceans and different parts of the same ocean contain different concentrations of salt. Go figure huh?

Anyway, reading the link and observing the calibration (if we want to call it calibration) I assume NaCl.

Ron

 

[KeepItSimpleStupid]

The list is specific except for package type. e.g. surface mount, radial, axial and that depends on construction.

Resistors are measured in ohms which is not stated. The R is used as a decimal point, so 470R is 470 ohms. 2K2 is similar. 2K2 is 2200 ohms. e.g. 2.2 * 1000
A trimer is a variable resistor and cermet is a type of element. Another type pf element is ww for wire wound. A trimmer doesn't have a knob.

For probes, you might want to use stainless screws.

The construction adds parts like the case and hardware.

Going to **broken link removed**

I used "resistor" as a search term. Under top results, there's "through hole resistor' . Now you get a table. Select wattage, 5% tolerance, Packaging (bulk and cut tape) and "in stock". Now 470 ohms, Just about any resistor will do. The prices range from $0.08 to $$0.59.

Carbon, film and carbon composition are the most common resistor construction. Metal film is a little more stable.

 

[atferrari]

The coastal areas of the US much like where you are have hundreds of rivers flowing into the oceans and like you I can go from a fresh water river to brackish water where river meets ocean to salt water where we are beyond the brackish mix and into the ocean. Ron

There is a berth in USA, IIRC Baltimore where we used to load coal; depending on what side of the vessel you sampled water, density was different. I found out that the reason was quite simple: on starboard side there was the mouth of a (small?) river / creek while on port side we had the whole water front.