Anyone up for voluntering for a pic project?

[Harry Bloomfield]

Please...

Assume - There is no money in it at all, though you would be welcome to any profits were any to be forth coming from sales.

Its fairly basic idea, just some means of indicating when a 50L barrel of water, on a caravan is nearing empty. Measurement input is from an hall effect flow sensor, sending one pulse per 2.25ml - so just a matter of counting the pulses. /444 per litre/22222 pulses per 50L

What is needed as output can vary based upon how complex you feel inclined to make it.

1. A single LED which flashes slowly at 10% left, flashes faster at 5%.

1. An LCD bargraph display showing exact level.

2. An LCD showing an actual amount of water used.

A piezo sounder might be useful for 1, 2, or 3, but would need a cancel button.

There are alternative barrel sizes to my 50L, 3. would be fine with any size, but to make it salable to others it would need to accommodate these other sizes.

I have no experience of pics and my eyes are not up to soldering such small items now. It is also 30+ years size I last did any programming, so though I know what is possible, I would not know where to start.

Water is pumped from the barrel by a small 12v submersible pump. The pump triggered by either a drop in pressure switch or a micro switch in each tap. Mine is a pressure switch type.

I'm not yet sure of the maximum flow rate, nor the pulse rate, but suggest it needs to go to an interrupt so no counts are missed.

Count should be reset on power up. My usual process is turn the power off to the pump, go fill the barrel, switch the power back on with a full 50L of water in the barrel. So when powered up, it is safe to assume a full 50L is available.

It should operate from a 12v (11v - 14.5) supply, using very little current. The flow sensor I have in mind already meets this spec.

I'll pay component costs, if anyone can do the deed and could maybe help with sales, if it becomes a salable item. I suspect 3 will be the most salable version as it is a fit all solution.

Other versions of this gadget rely on probes in the barrel, measuring conductivity and use an analogue meter to display the level. This needs no wires or probes in or out to the tank.

Anyone?

[tabbypurr]

Far simpler to stick 2 little metal pads to the outside of the barrel, and use 2 channel capacitance sensor + red & yellow LEDs.

NT

[Tim Watts]

I did one in the 80's.

This was based in an Aquaroll with the full length pipe guide tube that was part of the cap.

I bent 5 bits of 3mm stainless rod around the stiffener tube - one at the base as a common electrode and the other 4 at even levels from full,

3/4, 1/2 and 1/4 full.

Each rod has a slot in and was vice crimped around a stainless stell wire which was sleeved and ran up to the cap.

All 5 wires are silver soldered to a core of a screened multicore cable and set in adhesive heatshrink.

Plugged into a 5 pin DIN socket next to the water socket on the caravan, slavered in vaseline.

The display was trivial - 4 LEDS driven by a quad opamp package sensing a tiny (

[Tim Watts]

Good idea - easy to install...

[Harry Bloomfield]

Tim Watts laid this down on his screen :

I disagree. My first idea was to measure the time the pump ran for and use that as the measure. That would vary with voltage to the pump and start, stop v run times. I then found a very reasonably priced flow sensor, which should prove very accurate.

Once installed, no more needs to be done apart from remembering to always switch the pump off then back on, with a full barrel. No wires to outside, no probes, no sticky pads to come off and very easy to install.

Cut the main pipe, fit the flow sensor, connect the gubins, job done, no more messing.

[Martin Brown]

Why not just subvert a Watchman oil sensor for the duty?

It will almost do what you want out of the box except that it shows 0..F rather than a bar chart.

Ultrasonic range echo timing to the water surface will be more reliable than trying to measure the flow and intergrate it up.

[Harry Bloomfield]

Tim Watts wrote on 27/04/2015 :

A lot of quite unnecessary complication and expense, to use senders and receivers.

[Harry Bloomfield]

Martin Brown was thinking very hard :

Because it involves having parts outdoors and involves removing and fitting at each fill, plus some modification of the barrel, which would make the barrel unsealable.

[Harry Bloomfield]

Harry Bloomfield used his keyboard to write :

The barrel has two capped apertures, one on top, one on the side, with a spigot top and bottom. The latter allow for the attachment of an handle, to allow the barrel to be rolled along the ground rather than carried. My general solution I am satisfied with, as very workable, it just needs the hardware and software rather than an entirely alternative solution.

[Capitol]

Why not just stand it on some scales?

[Tim Watts]

Well, it's your idea - and you did ask!

[Roger Mills]

It seems to me that you're relying very heavily on re-setting it only when the tank is full - which sounds like a risky proposition, because the power supply could easily be interrupted at other times.

I agree with others that if it's the *level* that you're interested in, that's what you should be sensing - rather than trying to deduce it by somewhat dubious means. I'm not really up with the technology - but it may be as simple as having two vertical metal strips on opposite sides of the tank, and measuring the capacitance between them, which will presumably vary according to how much of the intervening space is filled by water as opposed to air.

[Dave Liquorice]

sender RF

Basic on/off modules are cheap, no need to design and build from scratch. Even ones that can send several states are still cheap.

And whilst I like wires, they work, are reliable and easy to fix. The great unwashed don't want the faff of installing them. They just want a sensor blob and a reciever blob that just works (FSVO: "works, just")

[Adam Aglionby]

Am I the first to suggest Arduino?

Ultra low cost, Nano under a fiver , RF link under a fiver.

Virtually no soldering, programming even a muppet like me can get something working with.

Level sensor bit more costly but abolute level sensing:

[Harry Bloomfield]

Capitol explained :

Not much better than going out and giving it a shake. Idea is to be able to check from inside and know when the level becomes critical, so something can be done about topping it up.

As said, I have the solution, it just needs someone with the requisite knowledge to be able to implement a pic to calculate and display the level inside.

[Dave Liquorice]

Hum, the sender part of a Oil Watchman Alarm sit's outside on top of the tank. It comes with a mounting collar into which it screws and sealing washer with two stainless steel self tappers to fix to the tank top. Ours has been outside south facing not shaded for 5+ years. It's just complained that it needs a new battery a single CR2430 lithium coin type.

The receiver is more of a problem as that is a well sealed/moulded plugin mains device. It would be hacksaw job to open it up to find what low voltage it actually lives off. You get a nice graduated display, pre-warning of "you better fill up" and "you really do need to fill up" with flashing LED and beep which can be disabled. If the level suddenly changes it'll wail at you. Tank depth adjustable from

50 cm to 300 cm in 5 cm steps.

Personally pulse counting strikes me as unreliable and the assumption that the tank is full at measuring device switch on. The must remember to power cycle pump/device when tank is full is not "consumer friendly". What happens if the device loses power? Some means of maually setting the level, again not "consumer friendly".

The dip wires strike me as simple, accurate and reliable.

[Harry Bloomfield]

It happens that Roger Mills formulated :

Very unlikely and not a disaster if it happened. It runs from a leisure battery, which is itself continually kept in a fully charged state from the mains.

If the barrel were a fixed barrel then yes, but as said this system has to be rolled around a field to fill it up. Plugging wires into it makes it even less user friendly. Measuring the amount consumed is more than accurate enough to satisfy the need, but with none of the other problems.

The barrel needs to be filled every day, day and a half. It just convenient to know, before beginning cooking or taking a shower, that there is enough water and to know before retiring that there is enough for next morning.

[Harry Bloomfield]

Adam Aglionby explained :

I originally thought Arduino or pic, but the sensing method itself is not acceptable. It has to be an internal flow sensor, generating pulses. Besides the flow sensor I have in mind, is a fraction of the cost of the item you linked to, and measures to 2.25ml and as its a pulse, much easier to interface to.

[Harry Bloomfield]

The barrel cannot be modified to accept something like this, its not an oil tank its for potable water. Even if there were some way to mount it, it still needs considerable modification before it will work.

A £5 flow sensor, plus a £5 pic beats the cost of that by a considerable margin.

[Tim+]

It's not exactly hard to wander round and give the barrel a shoogle! Caravanned for many years with an aquaroll and never felt the need to complicate things.

I did however fit a torbeck valve into a 5L paint pot with a hole in the lid so that if there was a tap available near my van, I could have a "never ending bucket" to pump my water from.

Tim