Due to my own conclusions at least in my country buying a commercial new solar water heating system on a turn-key basis is still not quite feasible.
However, if you are able to takeover some work yourself and you can get some used equipement, the feasibility changes drastically. Additionally if you make such project as a pleasure, you do not ask about feasibility anymore, it is just nice not having to spare any hot water at summer, and there are many ideas how to use the surpluss (e.g. connecting to a loundry machine etc.)
I'll note some progress here as inatalatin goes on (unfortunatelly I'm only able to do it at free time)
DAY 1-2
Used Collectors 2x2m2 brought to place of final installation (Paid 100 USD for each)
Then the instalation of pipes from the tank (300 l) started. I use both galvanized steel elements (1'' and 3/4'') and Copper pipes (most are 22 mm). PVC (PPR) is not used for solar here. Apparently temperature shocks would destroy it but I don't totally agree with that theory.
Using Galvanized elements is very simple with endless possibilities, but there are a lot of sealed connections, that's why I prefer copper where possible and it's also faster. Soldering is simpler than it seems, and can be mastered very fast. It is however a good idea to see how it's done before improvizing.
After the first day the pump is in place (paid cca 50 USD new, could find much cheaper one used). Why do I allways mention prices? Because the purpose of project like this is to return some money at the end, so it's good to have something to compare with. The price of complete pipes with fittings etc. was about 350 USD, because 40 m of pipes was needed.
DAY 2-4
After mastering sealing of Galvanized elements, some 20 sealed joints were done in only an hour. I don't know the english word for the plumbing fibres (Kudelja on Croatian) but it is apparently made from cannabis. This one however does not smell attractive when burnt. After that, the copper work started to go on, and soon the expansion vessel was in place on the wall. The progress was interrupted by some bad luck (electrical box in the way). Note that pipes shall only go up towards de-aeration, never sloped down, as it could create air pockets. That's why I had to go around it.
The purpose of this project was to complete a small experimental PV system (max. 70W, 12V, 50Ah) with a corresponding monitoring system capable of making data visible on the internet. The other purpose is to make this system additional educational note for myself and for the others that could be interested. It might be interesting to say that the budget for all electrical materials used (except the panels and battery) is fewer than 50 dollars. The main system components used are: - Raspberry Pi B+ - HD4470 4x20 LCD - 3.3<->5V bidirectional converter - Arduino Nano - Hall current sensor module - Solar charger regulator (10 A) - Used car battery (12V 50 Ah) - Cables and other items (see the diagram) The end result the webpage running from a webserver which consumes less than 2 W of energy and a reliable monitoring and control system with endless possibilities, at extremely low budget!
The described webserver is currently (hopefully with help of the sun) running on this adress:vladorpi.ddns.net
You can see some other details and photos on that page.
SOME PHOTOS
Late night pass/fail programming of outdors module (freezing...and sleeping on foot...)
Indoors webserver with LCD -- compiled in a teabox...
The original trick "similar" to this one was done by Nikola Tesla to impress the spectators many years ago. At the time, the great inventor had "nothing but" his brilliant ideas to achieve his goal, and thanks to that brilliant ideas we are able to do something like this today using nothing but general purpose electronics worth a couple of dollars.
This project is developed just to make a working hands-on example of integration of a few previously teststed ideas dveloped arround the ATmega8 controller. It is certainly not the simplest concept to achieve the desired function, but it does demonstrate some powerful capabilities of equipement used. Nicola (BTW who I'm proud to have as a neighbour in terms of birthplace - Croatia) would surely be glad to see how his inventions are used today by looking at examples like this.
THE FUNCTION IS...
To achieve a wireless control of former R/C control 4X4 car with a typical Gamepad as a controller. The PC is used in between giving some more upgradeable options, but also for the sake of simplicity.
SYSTEM DIAGRAM
THE PARTS OF THE SYSTEM
GAMEPAD
Any kind of typical "HID compliant" gamepad will be suitable. In this example it was a PS type wireless controller with possibility of analogue axis (not used here)
LAPTOP AND SOFTWARE
A windows 7 laptop with bluetooth adapter is used here. The software to receive gamepad data and guide it to car electronics is NI LABVIEW. More about this beautiful tool later.
SERVO MOTOR
Servo motor is used as a steering mechanism, just like it
would be on a classical car. To see more information of this motor you
may see my other blog posts like this one.
Servo motor: 9G
Servo Stall Torque at 4.8 V: 1.2 kg/cm (16.7 oz/in)
Servo speed at 4.8 V (no load): 0.12 sec / 60 °
Fitting (mechanically) of servo motor is not an easy task. I made a small crank out of a paperclip and had to carve a lot of plastic. The final result is OK but could be improved for performance.
MAIN MOTOR CONTROL
A PWM cntrol for main motor torque and direction control are used here, directed from the ATmega. The good all in one solution for such a task is the following DC motor driver IC:L293D. This chip had to be "dead-bug" integrated to existing board.
THE BLUETOOTH CONTROLLER
The connection between the PC and 4x4's ATmega8 board is made by bluetooth UART. For such a task, and if no long distance control is needed, the bluetooth module that one will most probbably use is: BC417143
THE 4X4 ELECTRONICS BOARD:
Last but the most important part is the ATmega8 onboard the 4x4 which controls servo and main motor, and does the processing of bluetooth UART messages. This board is used from my other project (solar controller) so the original PCB is modified to fit in properly and some additional components are added to the board. The one might want to consider using the Arduino (e.g. Nano) for this purpose not to get the hands too dirty.
NI LABVIEW
This great software from National Instruments is used to simplify data reception from gamepad, processing and sending out ti Bluetooth. LABVIEW could be defined as virtual laboratory, but it is also capable to make many other tasks like different forms of control. This powerful platform is typically used connected to laboratory grade I/O boards. But nothing stands in way to interface it with "cheap" but "powerful" world of general purpose microcontrollers!
Working in LABVIEW is simple due to intuitive block-typed interface and great number of online tutorials. Some of these tutorials are useful even if you are not considering using LABVIEW. I highly recommend this software. You can download a trail from NI site and give it a try.
The following "VI" is the one created in LABVIEW for this project. Note that this VI screen reads only the Y axis of controller. This is done for simplicity of view.
The upper line deals with reading the gamepad data. Y axis analog value is taken and then forwards a special character as a command for final action to ATmega8. For example it will send 0 (do nothing) if analog Y value is not higher than 10(forward) or lower than -10(reverse). Lower line deals with UART protocol which sends the data via Bluetooth com port. The middle part is actually a loop which executes continuously with 100 ms delays. Left side is initialization of GAMEPAD and UART and right side is closing of those once operation is terminated.
THE CONCLUSION
This system is tested successfully and everything worked as expected, so similar systems shall be easy to be built. I'll try to put some more photos/videos when I catch some time.
SOURCE CODES
I was not able (time) to collect all the final versions of my code for all the devices therefore one might have problems using that source. It is however not a very complicated code and presented VI shows the blocks which are used. I'll be happy to answer any question if being asked!
After this project I can enyoy playing with AVR and with my son at the same time.
Isn't that perfect?
There is a great selection of Lego Technic or even Mastermind availible. I personally think these are great toys for both education and entertainment. However, I like to make things my way, and also still need DUPLO size for my son (3+)!
EXPLANATION
How and what I did with pictures
STEP 1: Carving a DUPLO Brick and mounting a servo
The material of Lego is actually very nice for modelling. The skalpel or any knife can be used for initial carving. After that centre part can be milled by some kind of grinding tool.
Surely it can easily be done aesthetically better, but it fits perfectly even without a glue. One can also add some glue, while I like it to be more flexible (replacement etc.)
STEP 2: How to control the servo ?
Servo actuator is not really just the motor. In this case it is a complex system capable of holding the position we want very precisely, and moving arround as we command it. Inside the package there are: Electrical motor, high ratio gearbox, position measuring device and the control circuit. There are three wires coming out of a servo like this: Ground, +5V and signal line.
I did not like the way servos are controlled until I actually tried it.
One thing is sure - you won't be able to control servo without some kind of external control circuit. Micro-controllers are the most reasonable way of controlling a servo. They work perfectly as a pair.
For all my projects I use AVR. For this project I used both Atmega8 and Atmega32, but any other suitable uC can be used. Take a look at the mess of my control circuit:
It is not completely visible, since I packet it all inside a butter box.
The reason why to use micro-controller is the following: Servos need a PWM signal for setting the angle reference, and with uC you can very easily create PWM signal.
PWM stands for Pulse Width Modulation, and although it might not sound simple, it is not a very complicated concept. In this case, it means that servo will expect to be ticked in 20 ms (miliseconds) intervals at signal line. If not, it will simply not work. The angle is controlled by a duration of these impulses. Typically, a duration of 1 - 2 ms will mean a variation of let's say 180 degrees. For example, if you give an impulse of 1 ms every 20 ms servo will position itself at 100 °. If you give an 1.5 ms impulse it will position at 130 °. This concept is great because it gives you the possibility to virtually change the position every 20 ms. That's the frequency of 50 Hz by the way.
In micro-controller you can do this in two ways: Using PWM with 20 ms period (recommended) or manually using a simple delay functions. PWM method is neat because micro-controllers can do it automatically in the background, and it will not affect the rest of the program.
Here is the basic principle:
STEP 3: Programming the controller
I do not plan to go to the details of PWM programming, becouse many people already did that. There are some very useful links for this matter at the end of this post.
However, I'll post the C code here only to show how simple it is:
The code is made for: AVR , Clock frequency F_CPU = 1 MHz
If you ignore the complicated setup for registers (you can always just copy it), it is possible to setup the position by simply setting OCR1A. 1180 means 90 ° and 2050 means 180 °. you can also set other values. Usually, OCR1A values need to be adjusted by experimenting for different servo models.
STEP 4: Applications -- Finally!
Example 1: Brick lifter tractor
Example 2: The ramp
Example 3: The creepy bear
These examples are best seen in action on the video. Check it out here
First two examples are controlled as described. Third one is different, the position is proportional to analog input connected to accelerometer module. That way the hand follows motions of the module.
Anyway, servos are great devices, and except of these examples showing playing with them, they can be used in many serious applications. There are a few models available for under 4 $, and so far I haven't managed to destroy a single one, meaning they are also durable. I recommend trying to use servo to anyone interested.
SOME TECHNICAL DATA:
Servo motor: 9G
Servo Stall Torque at 4.8 V: 1.2 kg/cm (16.7 oz/in)
Servo speed at 4.8 V (no load): 0.12 sec / 60 °
Micro-controller: Atmega8, Atmega32
I'd like to share this little project, comprising of some interesting concepts. After learning a few things about microcontrollers and some peripherals, I wanted to finally create something that can move. Being short of time, I have chosen as simple solution as possible, and that was using one of my son's toys for my project.
Even before I wanted to use computer to program some actions, not only in software. This can also be called a simple robotic project, but let's leave that for some other. If you want to control something "live" with your computer wireless or wired, this is one of the good ways to do it.
I will present making of and principles in a few steps:
First of all, some technical data if someone is interested:
Used Vehicle: Jeep (Nikko)
Microcontroller:Atmega32 (AVR)
DC Motor driver IC:L293D
Bluetooth module:BC417143 On board LCD: HD47780 20x16
1. Disassembly of existing vehicle and preparation works
Not much of a craft, but it is good to have a good vehicle like this one. Here are a few photos from the start:
I decided to remove the complete original electronic interface. Original Jeep used 4 1.5 V batteries, taking two series, +3 V and - 3V out for forward and reverse motor direction. I took out only GND and +6V, as I have a special driver IC able to reverse the voltage. Of course, it is also needed to take out two motor leads.
2. Preparing the equipement
For my project's I usually use proto-boards, or specially designed universal board. I made this board myself for other purposes, but anything else with an uC on it can be used. Check out my References chapter at the end for details and interesting sources.
The setup in general
Bluetooth way of communication is chosen becouse it gives a very simple way of communication between devices in both directions. And the magic simple way is called UART. This name is related with serial communication by two wires (Tx Rx). This is used not only on serial RS232 port on computer, but also in industrial communication, with a similar protocol, only the equipement is a little bit more expensive. Bluetooth makes Tx and Rx wireless, not endangering the simplicity. Besides, almost every laptop or mobile phone uses a bluetooth.
I bought a 3.3V BC417143 based Bluetooth module, which I had to prepare for 5V levels used with ATmega32A. I suggest getting already prepared 5 V version.
Motor driver chip is L293D. One IC can handle 2 motors (starting and reversing), and is simple enough and cheap. It had been attached to protoboard on Jeep's hood. I suggest to use some of Reference links below to find out how it works.
In the video, you will see one wire coming out from the Jeep. At that moment I could not get enough power from my batteries, since I need at least 8 V at my regulator to get constant 5 V. Additional battery pack shall be attached to existing 5 V to achieve that, and at the time I could not connect all this so I just used "powerfull" wall adapter to get steady 9V. 12 V battery could also be used.
When everything is assembled, the Robo Jeep looks like this:
3. Programming, testing, getting it to work
It is preety obvious that this is the hardest part. However, since today there are a great sources online, it is only hard to learn how to use them. AVR is used here, but any other uC might be used for this. I use AVR with free AVR Studio from Atmel. DC motor driver is hardwired to uC with three wires. Two of them determine the direction, and one enables the motor. I also implemented PWM for speed regulation here, but it can also work without it (ON/OFF).
I also added HD47780 LCD display to this project only because it helps me to debug while programming, but later I used it do display messages sent from the laptop which is pretty neat. I suggest using such a debugging method, but it is optional.
So first I tested everything without any communication just to see how motor driver works.
4. Communication
Communication with the vehicle is actually the main task of this project. As allready mentioned it is done trough UART. The great thing about it is that UART function is embedded in many devices like micro controllers, computer COM ports, bluetooth devices. That makes using it more simpler, and hardware more usable and stable. Below is the diagram of the way devices are interconnected here.
Using UART it is possible to send some messages from one side to the other. Transmission is secured and monitored by hardware and works automatically. In this case, bluetooth adapter serves only as a bridge between computer and controller. The same could be done by connecting wires directly to the computer, using USB to UART converter for example. A good way of data can be transmitted this way, but in this project only some characters are sent, or a few words.
Generally, when you have UART ready you can use hyper terminal to send commands from the computer. For example you send F, and it means move forward for a part of second. FFFF would mean move forward a few times and similar. Also some special codes can be used to send message to display like ? Hello word sent means display Hello on LCD. This is the way it is done here. But if you want something nicer than typing commands you can also create a graphical interface. When you don't want to use special compilers like visual studio, you can use this trick: Use VBA - visual basic for aplications. That way I made the interface in Microsoft Power Point using VBA. It looks like this:
VBA programming is not very complicated, but in case like this you do need to find some specfic functions somewhere, or create it yourself.
This is all I will say about this project. It can be infinitely modified and enacted for many functions and purposes. It's purposes is only to demonstrate how this can work, and to relax a bit from some more complicated implementations. And by the way, this is my first blog ever, so I might have written too much, but I hope this is helpful to someone.
4. References
These references also serve as a thanks to all the great experts from which I learned so much.
Clearly, many additional functions and devices can be added to a project like this. For example, later I connected a servo motor and created a bluetooh controlled ramp (tollgate). My son had a wery neat new toy! Here is the photo:
And this is a nice site for instructions how to use a servo:
And by the way, servos are really great devices to use with micro controllers. Even the cheapest ones from ebay work nice. I have tried 9G so far, and it's just fine!
