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ultra sonic level controller

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What do you want to control the level of? Over what distance range will it be required to work?

I'm in the process of designing an ultrasonic water level controller for our underground water tank, which is 2 metres deep. However, I can't guarantee to have the design completed any time soon (if ever) as it's purely an optional extra.
 

geoffery

New Member
Well what i want to do is measure the depth of the tank it would have a max depth of 2 mtr and the distance from the controller is 3- 4 mtrs .
I want to connect it to a programable logic controller which in turn would control other devices there was a circuit in a electronic mag but i have been unable to locate it i think it was in a silicon chip mag

any help would be great

thanks geoff
 

mcs51mc

Member
Andrew Partridge said:
What do you want to control the level of? Over what distance range will it be required to work?

I'm in the process of designing an ultrasonic water level controller for our underground water tank, which is 2 metres deep. However, I can't guarantee to have the design completed any time soon (if ever) as it's purely an optional extra.
Amost 2.5 years later....

Do you have a working device?
Last year I also thought of making a US level control for our 2 underground rain-water-tanks but I stopped it because I didn't know if the US sender & receiver will work well in a moisture, humid environment.

So what's your experience with US devices in humid environment?
 

rcd316

New Member
Hi

Did u successfully build the ultrasonic level controller? I'm a student working on a similar project. I would be extremely grateful if u could help out.


Rohan
 

mcs51mc

Member
I didn't build one because I didn't know if these US units will work well in a moisture, humid environment. That was my question to Andrew Partridge, but I think his gone :cry:

Never the less, if it's for "normal environment" take a look at this site http://www.interq.or.jp/japan/se-inoue/e_pic6_6.htm you will find all you need on US systems with very clear explanation on transmitter, receiver detection, ...

You can buy US module's here:
http://store.qkits.com/results.cfm?CFID=1243518&CFTOKEN=10729524
or here
http://www.velleman.be/be/en/product/view/?id=355062

and build the µP part an write the code...
Good luck
 

philba

New Member
hi, I'm new here but have been around electronics a while.

You can get closed US sensors that can handle condensing environments though I have not found a source for these that will sell me a small number of them.

A completely different approach would be to use the capacitance between two wire loops. Water has a different dielectric effect from air and thus your loop capacitor will have a higher capacitance the more it is immersed. You can directly measure the charge time with a micro or use it as the capacitor in an oscillator and measure the frequency. A 555 timer works great for this. I use a PIC to discharge it and then measure the charge time. Takes calibration, though. Charge time is proportional to immersion level.

why loops? so no copper is exposed to water which will corrode it. I recommend teflon wire since a) stuff won't stick to it as well and b) to minimize dielectric absorbtion. You will need to build a frame to hold the wires rigid.

Phil
 

mcs51mc

Member
Any data available?
I mean:
Cross section of the wire to use?
Distance between the 2 loops?
What do yo mean by "loop" anyway? Is it 2 U schaped wires x cm away from each other? Or do I effetively need x turns (2 coils x cm away from each onther?
Maximum distance between the loops and the electronics (555 timer)?
 

philba

New Member
loop was a poor term to use. More like lengths of wire. Loop because I want only insulation to contact the water. My big probe (8 ft long) is two lengths of #28 stranded teflon wire. each around 16 ft in length and basically doubled back on each other to form a capacitor "plate". I use a 1.25" PVC tube to hold them rigid/tense. gauge and distance apart aren't critical since you have to calibrate it anyway. My "cap plates" are about 1/2" apart. From memory, it goes from <100 pf in air to several hundred pf immersed. As you can see, with the right resistor, you can get an RC time constant in millisecond range. Very easy to measure.

distance from the electronics in this case is about 4 ft but I think, again, it's not at all critical. If there is additional capacitance it just adds to the starting point (i.e. empty capacitance). I use a micro and have a built in calibration process. Not fool proof but I'm the only fool I need to proof against...

Phil
 
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