Coo... Did you see the price of those things? Our budget for materials is about 1/10th of the cost of a single sensor.Moe wrote:Maxbotic do IP67 sonars: https://www.maxbotix.com/Ultrasonic_Sensors.htm?1b8106
We did consider this as an option. The problem that we've identified is the build up of ice / condensation on the sensor faces, which will probably throw off the reading completely. Even if we found some material that is transparent to ultrasound, but impervious to water, this is still an issue.Moe wrote:But you probably don't need the performance for this application. If I was doing this, I'd get some HC-SR04s off Ebay and mount them in some cheap plastic hobby boxes. They will be facing downwards, so should be rain resistant to an extent (the IP rating standard IEC 60529 allows for this, if you have a hole in the bottom of the box to let water out).
Now this isn't a bad idea!! In fact the butts are probably around 200 litres, so the weight could be in excess of 200 kg. However a load cell to cope with that range can be obtained for around £15 on eBay.asandford wrote:The weight of the water butt will be proportional to the amount of water in it.
If you know the capacity and the weight, you can work out the level - if a 100l butt weighs 100kg (minus the weight of an empty butt) it's full.
We're kind of steering clear of reflective techniques, because of the vulnerability of the sensor to ice and condensation as mentioned above.bensimmo wrote:How much are laser distance devices coding now?
In a water butt you could create a float on say a rod that you can reflect off.
Or some strain gauge type float device (float connected wire string to a gauge at the bottom of the butt).
Or weight as mentioned above (external strain/pressure plates/setups.
Cheap small impellers/water fans you can place in the river flow ?
Just ideas sorry, no practical help here.
This has also been suggested elsewhere and certainly has the benefit of being simple. (We can also use GPIO pins and pull-up resistors to detect each level.)scotty101 wrote:Unless you need super accuracy, Conductivity probes are the simplest way to measure approx levels.
One probe detects tank full, One Medium and another almost empty.
The probes are nothing more than two nails seperated by small distance. and you measure the conductivity between the two nails. If they conduct, they are underwater.
Well. As a volunteer there, I can only suggest that you won't be disappointed.scotty101 wrote:This sounds like an impressive Model village! I'll have to visit if I can when i go camping in Dorset this year.
Yes it would give rrneous readings if and when it happened, but I have not experienced such problems in practice, and it's very easy to eliminate false readings in software. With cheap sensors you would have to eliminate the spurious readings anyway.We did consider this as an option. The problem that we've identified is the build up of ice / condensation on the sensor faces, which will probably throw off the reading completely.
I have to say that I'm unlikely to be there at that time; I only normally attend during the Open period if something has gone wrong (so obviously I'd rather not be there ). However, we might be progressing the River System development by then so you never know. Like most development, much of the work is done in my 'office' (a spare bedroom) and I only get out on site for integration.Burngate wrote:I'm also going to be close by, 26 June onwards for a week (not camping - too old for that - Chalke Valley History Festval) so if you're at the Model Town when we visit I'll say Hi.
My main concern would be if the acoustic signal was to be totally attenuated or totally reflected by the ice or condensation. That would be impossible to compensate for and could lead to flooding if the condition wasn't detected and dealt with.Moe wrote:Yes it would give rrneous readings if and when it happened, but I have not experienced such problems in practice, and it's very easy to eliminate false readings in software. With cheap sensors you would have to eliminate the spurious readings anyway.
Yes we could certainly do that. The current thinking is that we prototype a couple of solutions; probably the pressure sensor and this one and see what problems we have. If it was just measuring the depth of the water in the butts, then I would think that the pressure (or weight) approach would do the trick. However, we also have to measure the depth of the water in the sump. This is basically a concrete 'tank' about 40 - 50 cms deep, which is sunk into the ground at the bottom of the river system. We obviously can't weigh it and pressure measurements may not yield enough of a difference between normal and overflowing to allow us to predict a flood. The ultrasound sensors may be the best option here therefore.Moe wrote:In defence/aerospace we would use anti-condensation heaters where icing is expected to be a long term problem. In your case - if it became necessary - the ACH could be as simple as a big resistor stuck to the sensor mounting plate or the inside of the box, turned on via a relay when multiple erroneous readings are detected.
Yes. I had noticed that these are available, but I wasn't sure if they were a pressure sensing device or a simple pressure switch.Gavinmc42 wrote:Pressure sensors are used in washing machine for water level.
Now that looks interesting. We could still have problems with ice / condensation, but it might be easier to overcome that with this. It would certainly be easy to encapsulate this device with a clear window for the laser signal than to do the same for an ultrasound sensor.Gavinmc42 wrote:Time domain RF reflectance sensors are used for fluid levels.
Adafruit have a laser Time of Flight sensor that looks usable.
Ultrasonic plus laser, dual sensors for cross verification.
Maybe next year's projectGavinmc42 wrote:You need a town camera security system.
Pi cameras on poles so the rest of the World can explore your village.