@ericvdb said: The problem is that when powered with 12V, the transmitter does not see the 5V on the data pin as high. Then maybe you can try on 9v as @TimO has suggested, this may be close enough to register the highs and still give you the range boost needed. Otherwise it would seem you will need some form of line level shift circuit as @dbemowsk has shown. The only other option would be a 5v transmitter like the Dorji or similar

Here's one on AliExpress that can do 200 l/m: http://www.aliexpress.com/item/YF-DN50-2-inch-Large-diameter-turbine-flow-meter-water-flow-sensor-industrial-flow-meter-Available/32297810863.html?spm=2114.40010208.4.71.i72mzF. Not sure if I would trust it though.

@Yveaux ok thank you I will have a look at what is available in the arduino ports.

@AWI The code is from the MySensors examples and i use it to control 3 mosfets that controls a ledstrip. I need the heartbeat because i use the RPi gateway with the NRF24 chip directly connected to the RPi, and the gateway software for the raspberry dont store the network map so if i reboot the RPi the nodes loose connection to the gateway.

No it's not (as far as i'm aware of), The gateway is like it says only a gateway (in this case only data). This means the you should do some work on the controller to be able to send this data.

I use mssql database Cheers

@ericvdb (Vera guess) When given a fixed id enable inclusion mode so the device is found when you want to add it. If you are done you have to clear the eeprom and remove the fixed id from the code, and remove the device from the controller. After the above done, enable inclusion mode again and let the auto id assignment do it's work.

@GertSanders Yep.. misunderstood.., I thought you were basically saying "why would you use a pi instead of an arduino when the arduino uses less power, etc..." :-)

Yes, agree, Just sending pulses has its advantages.