Introduction: Remote Controlled & Solar Powered Watering System
Second Prize in the
Solar Contest 2017
Watering plants can be tedious, especially for those who have a garden in their house. I have to do this every day and it will be taking forever to get this done. Am one of those lazy ass who always wanted to skip this every morning. So I made this project while looking for an easy way to water my plants without any hassles most importantly with free energy.
From the above images you can get an idea about this project I believe. Unfortunately I cannot bring many plants into photo frame without making it look clumsy so sticked to using a single plant. While adding plants all you have to do is create a hole in the water pipe at appropriate places.
This is a wireless medium watering system using RF signals. And the most highlight feature which I enjoyed adding to this project is Solar power. This system is powered completely by the Solar power (except for the RF remote..quite obvious) . So in an essence this project uses Solar energy for its working and wireless medium (RF) for its controlling operation.
- 12V Solar panel
- RF RX and TX module - You could buy one or make one (if you are patient enough)
- 6V submersible water pump
- 7805 and 7806 Voltage regulator IC's
- LM324 Opamp
- NOT Gate IC
- Ex-or Gate IC
- General PCB board
- Connecting wires
- Soldering gun
- Glue gun
Step 1: Planning Your Project
Planning your system should be your first step. I believe the image illustration is pretty clear and you can deduce what I have planned. RF remote or transmitter will be with the user where a button press in the remote will activate the water pump.
The whole receiver unit is going to be powered by Solar Panel directly without using any batteries. The receiver unit comprises of Under voltage lockout circuit, RF receiver module, controlling unit and water pump. Batteries can be handy but will make this project bulk and costly. A special block called Undervoltage lock out circuit is used for stabilized operation of whole Receiver and pump controller block in this project.
The RF receiver will receive the incoming signals from the transmitter decode them and then feed it to the controller block. This in turn will operate the water pump to supply water to the plants. That's the whole idea behind this project.
Step 2: Choosing Solar Panel and Water Pump
Choosing your Solar panel holds a crucial part since the panel needs to meet the supply requirements of our whole receiver and controller block. As a rule of thumb choose a panel which has a rated voltage of about 4 or 5v than the max voltage required by the system. This is because Solar panels are not very efficient and will always exhibit voltage lesser than rated and it might get worse in non-optimum conditions such as cloudy or under shade.
In this case the receiver and controller block required a maximum of 8v to operate and I am using a panel rated 12v / 5W. The current rating of panel need to be considered as well. This panel is capable of delivering 416ma which is good enough for this watering system. Do remember that current from panel takes a serious setback under cloudy or shady conditions and the system won't work as anticipated.
Choosing the water pump holds the next priority since this will consume more current than any other blocks in the system. I have choose 6v motor which when tested with load (pumping water) consumes about 130ma. The current deemed to increase with the pressure (height water is gonna get pumped). After testing it out, it's safe to assume 130ma to 150ma as operating current. Fix a water pipe to the motor, if you are using individual plants create hole at appropriate place and you will be all set.
You may have to test your motor for current consumption under load because not all motor are same.
Step 3: RF Link - Transmitter and Receiver
As I mentioned earlier this system is going to use RF remote to control the water pump operation. In order to do this I have used a 433mhz transmitter and receiver pair which uses HT12E and HT12D for encoding and decoding purposes.
These TX and RX modules are easily available and can be obtained at any local component vendor or via online will cost around $10 I believe (approximately). Or if you are keen to make one on your own, here is a complete tutorial on "Making a RF remote from scratch" (Do note that you can ignore the controlling section in that tutorial since we will be using a workaround in this project).
Step 4: RF Remote Block
This remote block comprises of RF Transmitter module - HT12E & TX module ( Image 1). This module can only be powered by 5v. To make it portable I have opted to use the battery which is rated as 9v. So as you see in the schematic diagram (schematic diagram) a 5v regulator is used to convert the 9v to 5v and then supply it to the TX module.
A push button is connected to the data input pin AD9 of the HT12E chip module. The data input pins are active low so the other side of push button is connected to ground and button press will activate the input pins. Also pull up resistor was connected to D1 to prevent false triggering.
Step 5: Assembling RF Remote Unit
Time for some soldering! Assemble the components as per the circuit shown in the previous step. I used a general PCB board to assemble these and then later cut it out as per the required size. This shouldn't be tricky so make sure you do a good job with it.
Step 6: Why Undervoltage Lock Out Circuit?
Now we have reached the Receiver and controller block of this project. This lockout block is powered by Solar panel. If you take a look at the schematic diagram the voltage from panel is fed directly to this circuit. Basically this will prevent chattering of the entire system which is abrupt turn on and turn off in case when the condition is cloudy and solar panel doesn't generate enough voltage to power the system.
This lock out circuit is built using a schmitt trigger using Opamp. Schmitt trigger is basically a circuit which acts like a comparator with two fixed thresholds rather than one. It will monitor the Vin (input voltage directly from the solar panel)with the reference voltage in our case the voltage regulated using owner diode. I have used two 10k resistor in order to divide the incoming voltage from the panel. This is because of the need to compare incoming voltage with reference voltage Vref. For further explanation on Schmitt trigger kindly refer to this "Tutorial on Schmitt trigger". Hope this can give you some idea about it.
Vref of 5.1v is generated by means of a zener voltage regulator. This 5.1v is fed to the non inverting terminal of opamp and Vin to the inverting terminal. The resistor values R7, R8 and R9 decides the hysteresis value that is the difference between upper threshold voltage and lower threshold voltage. These resistor values are chosen to set the upper threshold voltage at 4.2 and lower threshold at 4v. By doing this opamp will only give low output when voltage from voltage divider Vin reaches around 4.2 and panel voltage around 8.4 (remember we divided the voltage into half) and keeps the output in that state until Vin drops below 4v or panel voltage drops below 8. Once dropped below 4v or 8v in case of panel the output in opamp will turn in to high output. You can refer to this Schimtt trigger callibration to choose the resistor and threshold values.
This output from Opamp will drive the P-channel MOSFET thus turning the receiver ON/OFF which in turn control the water pump. Since this is a P channel high output from Opamp turn it off whereas low output will turn it ON.
Step 7: RF Receiver and Control Block
This block comprises of RF receiver module which is powered from MOSFET of the lock out circuit as you can see in the schematic (image 1). So the RX module and control block will be turned ON just in case if there wasn't enough voltage fed to the system.
D9 which is the actual pin where we can obtain the data output. This will turn low if in case the button connected to AD9 is pressed at the RF remote input. But there lies a problem, when a HT12D it exhibits a active low state therefore there is risk in our project that motor will start to run whenever is getting turned ON. In order to eliminate this another data output pin was EX-OR'ed with this D9 output. As we know that EX-OR will only exhibit output if there is different logic states at the input. While starting up both the data output pins remain low state thus eliminating this problem. When a data input is given in the remote the D9 turns low while other data output remains high thus in turn gives high logic at the output of EX-OR gate.
The output of EX-OR gate 7486 will be fed to ULN2804A pin which is a darlington transistor array IC which will drive the water pump. This water pump and ULN2804A must be supplied with 6v hence a 7806 IC was used to do perform this operation.
I have tested these circuit blocks on a bread board before assembling them in a general PCB board.
Step 8: Assembling the Receiver Unit
Receiver unit might take some time and patience to complete since we are dealing with much more components than the remote transmitter unit. Once assembled make sure you mark for positives and negatives (very important). Once done use isopropyl alcohol to clean off the flux in both these boards to give a nice and finishing look at the end.
Step 9: Fix the Circuit Blocks
Now we are done with all the circuit building, it's time to set these circuit blocks in place for easier usage. I have set the circuits in a plastic boxes so that it can be easily carried around. Also, used a plastic box which comes with a cover for receiver unit so that the circuit can be protected from external weather conditions sun, rain etc.
You can use anything that is portable and can fit these circuit blocks inside it. Used a double side tape to keep the circuit and batteries in place. For the receiver block you need to remember that it's going to stay in the outside conditions so pick a box accordingly.
Step 10: Setting Up the Plant Watering System
Time to setup your project.
- Pick a bucket or other forms of water storage in your home, place the motor in such a way it is immersed quite deeply in water and water outlet pipe is outside the bucket.
- Connect the motor + and - terminals to Receiver unit which is placed in that black box
- Place the outlet pipe in your plant pot
- Connect the Solar panel positive and negative to the receiver unit and close the box to protect it from sunlight
Watering system is now ready and all left is to pick up my remote unit and water my plants :)
Step 11: Improvement Areas
This project can be off great help for those who have tough times in watering their plants on balcony, garden. Also utilizing the solar power it can save power. Here are few improvement ideas that you can consider while making this project for yourself.
Adding multiple receivers provide the possibility of watering plants at different places at the same time provided the receivers are in range with the remote
- High rated solar panel can drive powerful which can pump water to more heights.
- Using batteries with Solar panel can give you the option of watering plants in any condition
- This project is highly likely to cease working in cloudy or shady conditions
- Absence of batteries will make this project extremely dependable on weather conditions.
Hope this instructable would have been of great help to you. Do try this project out and let me know the outcome. Further improvement ideas are much welcome.
This project took a great deal of time to build and document it to create an Instructable. Kindly vote for me in "Solar contest" and "Lazy life contest" if you think it's worth it. Hope to see you with another instructable
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