Reservoir Waterlevel Schematic
 

I found a scheamtic on the web that uses four LED's to indicate waterlevel and alarm when the reservoir is full.

I duplicated the circuit to support 8 LED's, and modified it to alarm when the reservoir is empty.

http://www.paddedwall.org/watercool/..._schematic.jpg

I'm going to run this buy some of the engineer guys at work and see if there's any mistakes, and may be posting a new version tomorrow evening.

looking good! how much time do you have on your hands though?

Lots. :)

Didn't I tell you it was simpler? ;) I like the color scheme, it's really sharp looking.

Very nice indeed. Although I would wire it up to alarm when the tank is down to ¼ (just my opinion). My question to you is what type of switch are you going to use to sense the water level ?

The continuity between the probes is going to be the level sensor.

:)

I also think I decided to get one of the 6-inch criti-cool cylindrical reservoirs because I have more room for that than the bay-res.

Good schematic there.

>Although I would wire it up to alarm when the tank is down to ¼
>(just my opinion)

I think thats easy, just move the connection of the 2.2k resistor limiting the current on the transistors base to another point, so you can activate the buzzer in the level you want.

Btw, just a few questions :

The CD4066 is a quad analog switch, so how will it change the position connected with those copper/brass screws? Are you assuming that the submerged screws will conduct current through the water , and when the level drops it "cuts the power" to the screw?.

If so, then first, im not at ease of using an electrical circuit in water . Second, the conduction of electricity in water depends mainly on the impurities as far as i know. So using a very "clean" distilled water isnt going to invalidade the use of the circuit ?

That's one of the things I want to ask the engineer guys at work.

I'll be using Hyperlube in the distilled water. Isn't that an impurity?

>I'll be using Hyperlube in the distilled water. Isn't that an
>impurity?

Not that type of impurty. I was referring to dissolved salts and such in the water.

The more impurities (total dissolved solids) in water, the greater it's electrical conductivity. The amount of total dissolved solids in the water can actually determine the water's conductivity. The value of this factor (conductivity) depends upon the type of dissolved solids. I'm not really sure hyperlube will help. Depends on what it is made of.

Anyway, using that method (conductivity through the water) it might work, but then you cant use distilled water (imo). Maybe tapwater will have enought dissolved salts in it to do the trick.

Ions contribute to conductivity, polymers generally do not. Its a nonissue, you have copper, zinc, lead and possibly other metal ions dissolving from your block and radiator.

Question:

Since want to have probes in the water that are under an electric field, are you certain they will not react with the water? I once built a electrolosis device only to find that the copper leads had fully dissolved in a day (I was running 6 volts). The cell potiential of most metals with hydrogen is under a volt, so you may promote all sorts of fun reactions.

Electricity through water = short to ground through radiator (depending).
electricity through water = copper waterblock conducting electricity on top of your cpu core.
-Zoson

>Electricity through water = short to ground through radiator
>(depending).
>electricity through water = copper waterblock conducting
>electricity on top of your cpu core.

Not necessarely. If you increase the volume of water the electrical current needs to pass, you are increasing its resistance also. So, it will always take the path of least resistance. This will probably keep itself in the reservoir , and between the copper probes. Cant say for sure thou. A valid point nevertheless.

Redleader :

Did your experiment use tap water? Or some sort of acidic solution (which is higly conductive) ?

Given the metalic ions that'll appear in the water, it shouldn't be an issue. Either way, it can be compensated with added sensitivity. Easy.

A test would tell all. You'd really need to test it, if you're not going to have an available adjustment in the final circuit.

Don't let this deter you from using distilled water: it's more important to have distilled water, than to measure the level.

One of the engineer guys suggested I re-visit the infra-red thing. He's gonna rig up a test jig for me that will have an emitter/receiver pair on it, and we'll pass a partially filled lucite reservoir (distilled water and hyperlube mixture) through the beam to see what happens.

He also suggested a conductance coil with a donut float in the reservoir (would amost need to be a round reservoir as well).

Lots of fun things to experiment with. :)

I would be worried about current flowing from the sensor(s) through the coolant to other parts of the system (notably the WB). Just because it is a longer route doesn't mean no current will flow through it. If you run a 1Ohm and a 2Ohm resistor in parallel you don't get 0 current through the 2Ohm, you just get 1/2 as much. And it wouldn't take very much current through your CPU to fry it. If only 1/10th of the voltage you have in your sensors leaks back through your WB thats still (according to your diagram) .6V through the CPU, which is a lot for a CPU - I wouldn't want an extra .6V going through my CPU. Even if it doesn't fry it it will mess with the signaling and probably make it incredibly unstable.

But I do like the idea of a water-level LED array. If you come up with a fairly easy way to do it that keeps the circuit isolated from the coolant I'd definatly be interested in the schematic. As it is, I just made a small second window in my case right over my "res" (my 3/8" ID vertical fill tube) and put a blue LED behind that to make a little water-level-window.

But...
 

If you cant have any direct contact with electricity , then you're left with a few other options :

First , you can use ultrasonic emitter/receiver to verify the water lever, but that would have to be extremely sensitive. And it will produce notisable noise. I've mounted a couple of those , one in a small project of lenght meter through ultrasonic measurement ( a big pain ) and one in a small automated bot (self guidance system). Not my piece of PI.

Second, you can use several IR leds/receivers to bounce the IR light at the surface of the water, but turbulence, bubbles, foam, etc, distorts the signal. Or, you can use them in several levels, in opposite sides of the reservoir. When the level drops, the IR led gets the light across to the opposite sensor. Several levels can be added in a custom reservoir.

Third, a mechanical device of some sort, with a fluctuator attached to a variable resistance through a wire with a balanced weight, or something similar. Attached to a circuit, you can have a pretty good measure through a simple resistor divider or even a wheastone bridge, for something more sensitive.

Forth, you can use another type of mechanical device, using a magnetic/metalic (it can be anodized, or covered with a plastic filament) with a fluctuator, within a tube connected to the reservoir and rolled with a copper wire around its lenght. It would operate in a similar way like a Hall sensor, and it can measure the deviation of current done by the fluctuator moving up and down.

These are just some ideias so far. I'm more inclined to those last two. I've seen the third working alreay (in a lab experiment), and the fourth is an adaptation of a Bourdon pressure indicator sensor (LVDT). There are alot more of sensors , but most are for industrial applications, or are too expensive. We are looking for the DIY stuff right? Righhht :D .

BTW: A closed loop with a radiador doesnt really need a level indicator, IMO. However, in a bong/other evaporative cooling system (just like volenti's) , can make alot of difference.

My brother suggested that I find a scantily clad large breasted blonde bimbo to simply stand next to the computer holding the reservoir in provocative poses.

I was getting used to the idea when he popped into the room in a bikini and tried to demonstrate what he meant.


:)


Seriously though, yeah, I'm trying to keep it to a DIY thing.

That could work here, i've got a sister i can spare . :D

Anyway, phear my photoshop skillz. I've illustrated setting number four.

Is that green dude an algae molecule?

:)

no no no, the magnetic/metallic floater. It will induce a variation on the current passing the coil (in theory anyway).

Tap. I don't see how it matters, metals will corrode in tap just as easily as acid, both are conductive enough and the huge amounts of oxidized copper you'll be adding to the water won't exactly decrease conductivity either.

You can use a float (plastic) in a tube, and detect its position with the IR sensors.

small update.
 

I've found a way to maitain a similiar schematic (see Jsimmons first post) but not having any metal contact with the water.

The trick is to replace those contact points with a thermistor. Connecting the thermistor to a powered wheastone bridge can ajust the output level, and still connect to the switches. This type of system is called a Hot-Wire type measurement. It is supported by the fact that the thermistor in the water is hotter than the one above the water level. Or in cold water, cooler than the ones outside.

However it can be tricky to ajust. The water in a WC system is at room temperature with everything off, it warms up to a few degrees when the pump starts and when the pc is powered it (in average) stabilizes after a few hours at a given temperature depending on the system. Not knowing how sensitive is those logical gates, i cant really say if it would work with a oscillating voltage. I can however, be filtered or even attached to a regulator (see OpAmp basic circuits), but that will certainly boost the cost and complexity.

Another thing is displacer switches, wich are actuated with the connected floater operates a spring. Havent found much literature about it thou.


@ BigBen2k

>You can use a float (plastic) in a tube, and detect its position >with the IR sensors.

I've seen some problems with that . The actual big problem is that you need a good deal of area to bounce off the IR . It's easy to think that you can have an emittor and a receiver next to each other in a small tube but they generate interferance with each other, making that arrangement a faulty one. It does work however with ultrasonic measuring devices.

It can work having a emittor and a receiver at each top upper "corners" of the deposit (opposite), with 45º (ajustable) aimed at the surface of the water. The drop of level will alter the reception of the IR signal to lower points, thus giving a good measure of the water level. I've also seen a that type of measurement , i'll see if can post some diagrams today. Cant find any decent link on the web, but i have access to a few control and instrumentation books at school.

Ungh, i hate 6am posts. Big "no no" in the earlier post.

The use of a vertical mouting scheme on a IR emitter/ IR photo transistor doesnt work because the sensor reads the intensity of the light reflected on the water surface, not the time it takes to get there. So , in a vertical mount, there is little or no variation on the intensity. Only in an angular mount it can change with the change of the level. The angle of the refracted light changes and so does the intensity reaching the IR receiver. Thus reading a variation on the water level.

Of course, we're assuming there isnt any foam , bubbles or alot of agitation .