When going portable with your electronics projects or diving in to RC hobby you eventually have to deal with batteries. No secret that best what is available today is lithium batteries. They come in many flavors. Why use lithium battery instead of alkaline or NiMh rechargeable? The short answer is – energy density. Lithium Ion batteries can store large amount of energy comparing to its weight and can give out large currents. This technology made it possible to enjoy long and powerful RC model (like quadcopter) flights. To achieve same results with NiMh it looks almost impossible due to weight and low current output. Lithium battery technology is constantly improving as different chemistry is used. You can find lots of info about different chemistry of Lithium Ion batteries so we won’t be getting into this.
Using relays are a common way of switching high power loads with electronics. If you take any microcontroller or any other digital IC, you will see that their output current on a single pin is very limited – varies around 20mA. The same situation is with voltage. Digital pin output voltage is limited to IS supply voltage like 3.3v or 5V. Usually, we need to switch loads that draw significantly higher currents and are powered from a higher voltage supply. And there you have several options for switching loads. One and oldest method is using mechanical relays. They are still a very popular way of switching power electronics. One biggest disadvantage of using mechanical relay is that it has moving parts with all rising problems. These are: slow switching time; relatively high control current; noisy; may produce sparks on switching; sensitive to environmental factors like vibration, humidity; To overcome those problems there is a more modern solution – a Solid State Relay (SSR) also known as a single phase power controller. Instead of switching loads mechanically, SSR does this with the help of electronics.
In many cases joystick manipulator is best choice for user input. Whether it is a game, robot or flying machine – joystick is most intuitive way of controlling them. You can actually find them in gaming controllers like PlayStation or XBOX. The one we are going to interface is Thumb Joystick I purchased some time ago from SparkFun. They are really cheap and as users report it is practically same as in XBOX 360 which can be replaces if one is broken. I didn’t bother making a PCB for it – just used a breakout board for it which also can be found on SparkFun. Simply speaking this joystick is nothing more than two potentiometers and one pushbutton. It is designed so that potentiometers are oriented perpendicular and thus moving stick you can have X and Y axis control. Push button is simply action button which can be activated by pressing joystick down. So controlling joystick is a matter of analog read of both potentiometers with microcontroller ADC inputs.
Python is a great programming (scripting) language that is supported on all platforms. Embedded enthusiasts love it because of variety of modules that allows connecting things to internet and other crazy stuff by writing only few lines of code. Today my interest was to read serial data with using Python 3.3 and pyserial module. Python 3.3 is still new and there is a majority of modules that needs to be ported from Python 2 to Python 3, but I hope soon they will here. Serial module seems to be working fine in Windows 7 x64 and decided to share my experience. First of all download and install Python 3 (current release is Python 3.3) Just be sure to include “Add python.exe to Path” so you could run Python anywhere in you computer. We wont go in to details on how to setup this tool. It is pretty robust. After setup python install is placed in C:\Python33. To test if things work OK open command prompt and type python you should see python prompt:
Take any professionally made PCB and you will find that in most cases areas between traces are filled with copper areas. In fact background fills can give benefit but also be harmful to your all design. Dangerous prototypes have written a tutorial on how to make MCB background fills look professional and add additional features to schematic. In most cases background fills are connected to GND in order to reduce resistance and electric noise. Keep in mind that filing grounds where ever it fits can also have negative effect – for instance ground planes near signal traces may add parasitic capacitance. In this case probably better use hatched fills or avoid them at all. Sometimes it is useful to draw custom ground planes around power traces to make them more thicker in order to carry more current.
Whenever you deal with electronics projects, one of the headaches is designing a power supply. Depending on your needs you may need to step up the voltage. Let’s say from 5V to 15V, step down or even to convert it to the negative voltage. David L. Jones from the eevblog has prepared great video post where he takes us through all steps needed to design step-up DC to DC converter. He chooses well known and widely available converter chip MC34063 which can be used almost for any type DC to DC converter including step-down, step-up and inverting supply. All required formulas you will find on datasheet – all you need is to select output current and output voltage. All needed component values can be easily calculated by using readymade formulas or online calculator. Additionally, David made a real design test with load efficiency charts. After this, you will find that designing switching power supplies isn’t so hard. [EEVblog#110]
Motors are the general components that we’re normally used in many industries, such as electronic, electrical, automobile, engineering and much more. Electric motors are the main key of converting electrical power into mechanical power. Since the electric motors are simple and reliable machines, hence they can be found all over the place, in whatever shapes and sizes you want it to be! Don’t believe it? Well, maybe some examples will convince you here: The powerful starter motor Alternating windshield wiper motors Intermittent-use power windows and door locks The blower fan that moves hot and cold air into the cabin The Tiny motors inside the CD player However, please stick in your mind that motors are slightly tricky loads to control. Their current can be totally varied with loading, starting and stopping, where it can causing a danger to other circuit components, if you didn’t handle it carefully! Well, you might want to carry out the eight quick motor experiments and see the result by yourself, which as: Spinning the motor to make a voltage. The motor can be used to light an LED, if you’re spinning the motor properly. The inertia keeps the rotor spinning. The Winding resistance of the…