water reservoir level sensor

[Borisw37]

Doesn't the parallel port look like a memory when programing? You can read from it and write data to it. Doesn't it have its own address in memory? And this memory location is refreshed on a rising edge of a dedicated clock signal. Isn't this the difference between parallel and serial? Parallel requires the source and destination to have the same clock speed. Where as serial uses "handshaking" to determine when a data word is sent.

Actually you could be right about the timing of the input signal, etc...
I'll have to read up on that.

 

[trend]

Here are some test results: tested a AA battery, when i hooked my voltage meter to the battery.. I got 100percent (sorry it says 12, but i don't know 12 of what), when i tried filling a small paper cup with water (about 1/5 full) and tried conducting the battery through there, i got about 1/6 of the voltage ..

hm.. Hopefully the parallel idea will hold up, so atleast i will have something

 

[Gentleman]

If you want to use the parallel port, I think you need a 555 timer to give you your square wave signal, but you might get away with just sending a constant high input into your clock pin. This might work depending on the UART of the chip on your mobo. I think a better way was with the fan monitor idea. You can use your reed switch ladder as a variable resistor which would control the frequency of an 555 timer. This modulated signal can then be inputed into the fan controller pin on your mobo. You then write a little program that looks at the value of this signal and convert it to your volume scale. This is pretty easy to do for only one level monitor. But if you wanted to use this for multiple level indicators, you can use a switch to change the input signal and modify your program to look for this signal change.

I think this method is a lot more realistic than the parallel idea.

As for the letting the water complete the circuit. You gotta consider what kind of additives you have in it. Also, at a potential of 5 volts, water will start to separate into oxygen and hydrogen, and you know what happens when oxygen and hydrogen do when they meet a spark don't you?

 

[trend]

i'm going to have to have multiple level indicators, and i want to see them all the time..
So back to parallel?

 

[Gentleman]

Read my edited post...

 

[trend]

The liquid level sensor I have is a solid state. (can't do a direct link as you need to start a session), but go here www.rswww.com and type 317-803 it their search engine. Not used it yet so can't comment on it further, but it works in testing. It has no moving parts and is fully sealed / inert to the coolant.

As the description says it simply works on light refraction, so when the sensor is under the water level it's fine if the level drops below the sensor part it affects the light refraction and triggers the sensor to trip.

I wonder.. could i mount this sensor vertically, and it tell how much water is in there by the amount or lack of refraction?

thanks-Lee

 

[trend]

well.. I think the easiest way to go would be a Flow Sensor. but I cannot find one for VERY low flow and that will have digital outputs...

hmm any suggestions?

thanks-Lee

 

[Gentleman]

I think those are just switched and not variable resistors so i don't think you can use it in that way. Its either on or off. These would work well if your have a colum of them to sense the water level and turn on when the water reaches it.

How well do you know electronics? It is possible to build what you are wanting, but it take a bit of technical knowledge to know how to make the timers and switches needed for a multi sensor setup like you wanted, but certainly possible.

I have made something similar for a school project. I used magnetic reed switches as a level indicator, but instead of using it in a tube and sliding magnet setup. I had the reed switches attached on the inside of a PVC pipe. On each switch, there is a little magnet that floats and is hinged to one end of the reed switch, as the water level rose, the float would lift the magnet away from the switch. So as these magnets came away, the reed switches turns off. I used this resistor ladder to modulate a signal that the microprocessor i was using can read and output.

In your application, making a resistor ladder is not a problem whether using the reed switches or the photo switches. Your biggest challenge is your interface with your computer. Making an interface for one sensor is not a problem, the problem lie in you wanting to use several sensors. Whether you use the parallel or fan monitor method, how are you gonna determine which signal from which sensor you are reading? Again I don't know how knowledgeable you are with this stuff. Do you understand what I mean when I say you can use a multiplexer to increase the number of sensors that can simutaneously attach to a parallel port. OR you can use several LM555 timers to interface your sensors with the fan monitor signal, and use PMOS switches with to switch between different sensor signals.

 

[trend]

hmm.. suppose i did go with a flow sensor.. Would it be able to tell if there was liquid or air going through it?

hmm.. soemthing to sleep on

goodnight

 

[squeakygeek]

In your application, making a resistor ladder is not a problem whether using the reed switches or the photo switches. Your biggest challenge is your interface with your computer. Making an interface for one sensor is not a problem, the problem lie in you wanting to use several sensors. Whether you use the parallel or fan monitor method, how are you gonna determine which signal from which sensor you are reading? Again I don't know how knowledgeable you are with this stuff. Do you understand what I mean when I say you can use a multiplexer to increase the number of sensors that can simutaneously attach to a parallel port. OR you can use several LM555 timers to interface your sensors with the fan monitor signal, and use PMOS switches with to switch between different sensor signals.

You are talking us in circles. Please read all the posts. A resistor ladder IS going to be a problem, for precisely the reasons you mention. The parallel port has 8 data bits that can be used - one for each sensor. No timers will be needed. While the fan idea might work, it would be rediculous to implement it when there are much better ways of doing it.

As for the flow sensor, there is a diagram here:

http://www.overclockers.com/tips1122/index02.asp

I don't think air would be able to push it, but you could fine-tune it to your situation. You could also use the flow sensor design to make a "floater" for each level sensor, so each sensor would be on if it's under water.