I am trying to create a wireless automatic pool filler. Have have an HT12E encoder to change the parallel data from the sensor into serial data to be broadcast from the 418 Mhz RF Transmitter module to a 418 MHZ RF Receiver. It will then go through tan HT12D decoder to a latching switch powering a solenoid.I want to use the RB-Wav-39 to send a single signal to turn on the water when the level is low and send another short signal to turn the water off when it has hit the high mark. I’m sure this is possible but I need some help in figuring out how to do this. Can someone help me. I want to send a single pulse each time to conserve battery power.
Hi,
Here are answers to your questions & comments:
To save battery power, you would most likely want a low power microcontroller on the sensor side. Of course, you’ll want to use power saving modes and maybe even turn off the sensor when not reading it (maybe once every few minutes or something similar). A microcontroller in this case is also helpful because you want should be adding hysteresis to your system (i.e.: prevent water from turning on/off at every reading when near the level needed). This can be done only with electrical components, but considering the simplicity (and low cost) of using a microcontroller that would be the recommended approach.
Also, even with the encoder/decoder chip you would probably want to add some form of protocol with error checking (and maybe even encryption?) to prevent erroneous signals from turning off or on the water when it is not supposed too. I have a strong suspicion you do not want to come back to a overflowing pool. You may also want to put a electrical “kill-switch” with a second water level sensor above the first one at the “must stop now” level that is connected to your water output that can turn it off when it is reached as a safety measure.
We hope this helps you get started.
Sincerely,
Would an Arduino Uno R3 be a good microcontroller to use. I was thinking of turning on the sensor and checking the voltage every ten minutes. If it is equal or less to the lowest voltage it sends an ON signal, then turn it back off. If it is equal or above the sensor’s highest voltage the controller will send another ON signal to turn the water off. As a back up I thought I would start a timer for the time it takes to fill the pool and would send a stop signal. If the high voltage signal is triggered the timer would be void. Don’t know if this would drain the battery to the controller much. No sure how to make sure the low voltage is backed up. The H12e and H12d have an encryption feature to ensure no false signals being processed. I hope I can find code help in Arduino samples. Does this seem like a good plan?
Well, it seems like a plan. Since you seem like you have most of the components already, I recommend that you try it out! Build your circuits, implement your code design and see how well it works.
Maybe also place a multimeter (in current measuring mode) in series with your battery for the sensor side and see how much power is used so you can get an idea of your power profile.
This will allow you to gather data about your project and how it performs (and also leave the world of theory for the practical world). Experimentation is an important learning tool and most products go through many prototyping stage. Just assume your first attempt won’t be perfect, figure out what you can improve and move forward from there.
If you want to conserve power the Arduino Uno R3 is probably not the best choice since it is meant to be powered by a stable power supply (from an AC outlet) or a USB port (also goes back to grid).
You’d want a more microcontroller board optimized for low power operation. But, this is off in the future! Start out with your Arduino Uno R3 for now and get your project working as required. Then, and only then can you start optimizing (if even needed at all) 
Sincerely,