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The website does not make it very clear, however if the meter is equipped with only a reed switch and two terminals connected directly to it, then you should be able to connect directly to the Pulse input. If you find the switch contacts "bounce", you might have to employ some software logic to give the correct count.

Thank you for your answer.

Sorry for the maybe stupid question, but what do you mean by "two terminals directly connected to it" ?

I have two wires, one white, and one brown. I'm not sure how to plug it on the jack, because there is 3 wires on the jack...

Can you help me more ?

Look at the emonTx circuit diagram. The sleeve of the socket is connected to 0 V (GND), the ring to the input DIO3 / IRQ1 and the tip to a jumper that connects to either 5 V (PWR) or 3.3 V (VCC). There's a 10 kΩ resistor R8 connected between ring and sleeve, which is marked "optional" on the PCB, and which you'll need. You connect the switch between the input and the supply to pull the input to logic HIGH when the switch closes, and the resistor is to pull the input down to 0 V (logic LOW) when the switch opens. So wire the switch to tip and ring (either way round) and drop a blob of solder to link the middle pad to 3.3 V (VCC) pad - these are just behind the socket, clearly marked, but get the correct socket.

By "two terminals connected directly to it" - I meant there needs to be nothing else in there except a reed switch.

I tried every combinaisons with the jack, to my two meter's connectors.

But i have no real pulse, i only see random pulses when nothing is connected.

If i try a multi-meter, i have no resistance from the two meters' connectors, like it was a simple "wire"...

I don't understand how i can use it with the EmonTx :-(

Oh, i didn't notices your last post, i will take a look on this "pull high" logic. That can make a sense, because the meter seems to be always high for now.

Thank you.

If i try a multi-meter, i have no resistance from the two meters' connectors, like it was a simple "wire"...

Did you watch it with a tap running?  If it pulses once per litre, you should see the switch open and close as the meter ticks over.   If there's no water being drawn, it will stop in whatever position it happened to land in, possibly open or closed.

Have you fitted R8?

Hello,

Yes, i added a 10KOhms resistor on the R8, and soldered the 3.3v jumper.

Here's the photos of what i done in attachment.

I tried to use the arduino program called emonTx_Pulse from the emonTxFirmware-master package, then i breathe into the water meter to make the inside to roll, but the serial keeps displaying a stable value like that :

...
-23232W 0
-23232W 0
-23232W 0
-23232W 0
-23232W 0
-23232W 0
-23232W 0
...

I tried every possibilities of connectors from the Pulse jack, and the values are never changing despite my big breathes :-(

Did i forgot something ?

Thank you for reading.

1. Disconnect your water meter from the emonTx. Does the meter register when you blow air through it? It is possible that the water meter will not register air (because it is designed to register only water!)

2. When you connect your multimeter on continuity (Ohms) to the water meter and turn the water meter slowly, do you see the resistance change from near infinity ( > 1 MΩ ) to near zero ( < 5Ω ) and back for each litre of water?

3. If you connect a push-button to the plug - between tip and ring, does the emonTx count pulses?

Hello,

1. I tried whith water, it's the same... :

2. Nothing, i have 0.5 Ohms whenever i breath in it, or use real water, or let it idling... :
0W 0
0W 0
0W 0
0W 0

3. It seems to make some figures, although i'm not sure about their signification :
0W 0
0W 0
-3400W 1555
-3400W 2846
14628W 2396
23785W 1462
23785W 0
23785W 0

The seller of the water meter said he only has the specifications given, the answer was :

"It is a potential free reed switch output, the frequency is 1 pulse per 1 litre, it requires no power.
Does that help?"

...Thank you for you help.

So it looks as if the reed switch should be OK to connect to the emonTx.  The numbers "1555" ... mean that there were 1555 pulses counted during the time period between printing the numbers out (5 seconds ?), so something is happening.

The "xxxx W" number assumes each pulse is 1 Wh of energy and so calculates the power based on the time and the number of pulses. You don't want that of course, only the count of pulses to give you the number of litres.

Meters like yours usually work like this: there is a wheel that turns once per litre, on the edge of that wheel is a magnet and the reed switch closes as the magnet comes near, then as the magnet moves past and away the reed switch opens.

As you never see the switch open, I think it might be that the reed switch has stuck closed. It is possible that when you "tried every possibilities of connectors from the Pulse jack", you could have connected the reed between the power supply and ground and when it closed, it short-circuited the supply and the high current welded the contacts together. If that has happened, you could try hitting the meter with something like the handle of a screwdriver to try to separate the contacts, but when you do that you might also damage the meter. Otherwise, you must get the meter checked and if necessary, repaired.

Thank you again for your time.

I tried to hit it, it does not change anything :-( I didn't know i could broke it ! 50£...

Fortunately i bought twice of this same water meter.

I tried the second one, plug it, tried two air breathes and... :

emonTX Pulse example
0W 0
0W 0
0W 0
7068W 12
14628W 2
14628W 0
14628W 0
14628W 6
14628W 0

It works ! ...

Well, does that really mean i lost 50£ of the first water meter ?

Thank you for reading.

I'm sorry, but I think it does. Why not contact the supplier and ask if they can repair it, and how much it would cost?

If it's really broken and costs too much to repair, can you take it apart yourself and replace the reed switch? These cost very little.  If you are very careful, the meter should work, and if you do this before you fit the working one, you can connect the two in series and use the good one to check the calibration.

Hi,

I managed to unmount the "electric" part of the water meter (see the image attached).

The rest seems to be really badly stuck, the plastic can't be opened more... without break i think.

I asked the supplier if i could get a replacement for the grey part, maybe it's cheap.

Thanks again.