Domoticz

Hello Paul,

I'm trying to replicate your awesome setup, and have some questions about it:
* When my sensor arrived (exactly the one you linked - from dx.com), the glue was still liquid and the electronic components and wires could be freely pulled out of the metal housing. And now, 4 weeks later, the glue is still liquid, as if they used the wrong kind. I used some adhesive tape to keep everything in place, and somehow the sensor seems to be working just fine... I wildly assume your sensor was in good condition on arrival?
* What's that metal bar you use to attach the sensor to the watermeter? I've been to Praxis, but they don't have anything with a 1cm (!) hole in it.
* Do you really have a dedicated power supply just to power the inductive sensor? I found that 5V from the Raspberry Pi is enough for the LED to turn on and off when metal passes the sensor, but it will *not* affect the (black) output pin at all. With ~7.2V everything works fine.
* Has there been anything else that you noticed or modified since the last post in this thread?

Cheers,
Sebastian

Hi Sebastian,

I wildly assume your sensor was in good condition on arrival?

Yes it was (and still is)... Never noticed anything like that.

What's that metal bar you use to attach the sensor to the watermeter?

It's the kind of bars they use to separate the curtain rail from the wall. Like this: A large hose clamp circumfences the meter and fixes the bar. You might have to widen the slit.

Do you really have a dedicated power supply just to power the inductive sensor

The 5V is just not enough, sadly. I took a small 12V wall plug to supply the thing.

Has there been anything else that you noticed or modified since the last post in this thread?

No. Actually i'm not sure wether i used a Mosfet or Reed relay to switch the PiFace. Need to open the box
/paul

For the metal bar you could use a so called 'hoekijzer'. They have them at the metal department of your DIY store. The hole you could drill yourself

For the 12V powersupply, i also needed 12V for a project (cheap 433Mhz remote that is triggered when my doorbell is pressed) and i made a Y-splitter wire. Input is the 12V from my router adapter, output 1 goes to the router, output 2 goes to my remote. Works great and saves you from having another powersupply draining power 24/7.

I suppose the amount of devices you can power with a single power supply is limited by its amp output? My Raspberry Pi is powered via 5V mini-usb... and that's currently the only power supply in there, so I'll have to dig up another adapter for the sensor.

Furthermore, I've been wondering about your circuit, and forgive me, I've only had a couple of courses about electronics so I'm stuck with just the basics.
Since you already divide the sensor output with the 2 resistors, what's the purpose of the transistor (or relay switch)? Can't you just connect the 'split' output (which switches between 0V and 3V in your example with a 6V power supply) straight to an input pin of the Raspberry Pi?

Hi Sebastian,
The circuit is there because the input of the Piface uses an internal 10kOhm pull-up resistor from Piface +5V to each input. Our circuit needs to pull this input below 0.7V to have an active input. A NPN transistor leaves a to high voltage from collecor to emitter in conducting state. A mosfet does not suffer from this.
But.. To make things easy: Scroll back to post #29 and check which type of sensor you got. Place a reed relay's coil at the position of "load" and have its contact switch the Piface input to ground. In that way both 12v circuit from sensor and 5v circuit from piface are nicely separated.
/paul

I don't use piface, just raw GPIO pins.
Afaik, they don't have internal pull-up/down resistors, but in the circuit displayed below I would think that the signal is stable in any state, and within the voltage limits of the Pi. Or am I missing something?
Note: This is an unverified schematic, do not use this


Btw, after-care of dx.com is pretty impressive; they've already sent me a free replacement sensor in response to my negative review.

Hi Sebastian,
Ah! That explains. I checked these pages which show you could indeed use a simple divider.
BUT:
- GPIO input is active at 3.3V. A voltage higher than 3.3V should never be applied. See specs here. So the divider should be more like R1= 1k5 Ohm and R2= 560 Ohm if 12V is applied to the sensor (or R1=2k and R2=1k at 10V).
- Also GPIO have configurable 50K pullups to either 3.3V or Ground (see specs above)
- A mistake is easily made so i strongly suggest in having both circuits (using different voltages) isolated. A simple € 4 reed relay could save you a €35 Raspberry Pi.
/paul

hello
i have a LJ12A3-4-Z / BX sensor but when I put him on the water meter
like he does not detect the metal surface.
if I had a screwdriver to hold the sensor does it.
you may know how this can I have the same as your water meter.

Mark

you may know how this can I have the same as your water meter

That's hard to tell... Mine is directly on top of the glass of the water meter. The sensor should be able to detect the disc at 4 mm distance according to the specs. Had to use a supply voltage of 12V to have it work properly. 5V is a no go. Otherwise you might have to try ordering another one. You could have bad one.
/paul

I use as feed 12 volts DC, so it will not be the result.
The sensor works as normal when you hold for iron.
I myself think that those 4mm to detect just is not enough.
Do you know the same type sensors but with a greater range.?

Mark

Keptenkurk wrote:Today i mounted and connected the proximity sensor and got it all working.
So now we are singing "Let it flow, let it flow, let it flow"

Merry Christmas to you all and a big THANK YOU to all involved with Domoticz.
/paul

the parts.jpg

mounted sensor.jpg

EDIT: Changed the schematic to use a reed relay instead of the 2N7000 Mosfet

Proximity-Sensor.png

Thanks for sharing. This looks like a really nice solution. Especially when taking in account that an off the shelf solution comes down to 125 euro (Pulssensor Cyble + S0 Pulse).

Would it be possible to connect this circuit directly to a Arduino Uno? I guess my question is, what is the advantage of connecting it to a PIFACE instead of directly to GPIO ports?

Thanks!

what is the advantage of connecting it to a PIFACE instead of directly to GPIO ports

There isn't
At the time i built this there was no GPIO integration in Domoticz yet.
/paul

Stops working: (

Again busy to got this working without succes.
Please could somebody tell me where to place the inductive sensor?


I already keep the crane running and looked for a place but no respons nowhere

It should be the red half moon disc. However my version has a metal piece glued to it. Yours looks to have a printed circuit coil instead. It might need the Pulssensor Falcon PR6 to get pulses out of it.

Whoops, double

Keptenkurk wrote:It should be the red half moon disc. However my version has a metal piece glued to it. Yours looks to have a printed circuit coil instead. It might need the Pulssensor Falcon PR6 to get pulses out of it.

Indeed there's no metal disk on it .
Is there nobody who can tell us what's inside this RB-6 pulsemeter ?
When we turn on the crane there a ticking noise which can tell us that there is something like a pulse, but where and how
The RB6 is also to expensive

What could be the exact place for this (magnetic) pulse ?
Or is there an easy way to find it ? (Tried googling this, but nothing)

Where's the best place to place this sensors ?

Nobody ? :s

is there nobody who can help me ?