Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

General requirements for handling LiPo, LiIon and LiFe batteries

When going portable with your electronics projects or diving into RC hobby, you eventually have to deal with batteries. No secret that best what is available today is lithium batteries. They come in many flavours. Why use lithium battery instead of alkaline or NiMh rechargeable? The short answer is – energy density. Lithium-Ion batteries can store a large amount of energy comparing to its weight and can give out large currents. This technology made it possible to enjoy the long and powerful RC model (like quadcopter) flights. To achieve the 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.

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Considering Solid-State Relays (SSR) for your projects

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 minimal – 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 trendy way of switching power electronics. One biggest disadvantage of using a 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.

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Using analog joystick in AVR projects

joystick

In many cases, the joystick manipulator is the best choice for user input. Whether it is a game, robot, or flying machine – a joystick is the most intuitive way of controlling them. You can actually find them in gaming controllers like PlayStation or XBOX. The one we are going to the interface is Thumb Joystick I purchased some time ago from SparkFun. They are really cheap and as users report it is practically the same as in XBOX 360 which can be replaced if one is broken. I didn’t bother making a PCB for it – I 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. The push-button is simply an action button that can be activated by pressing the joystick down. So controlling joystick is a matter of analog read of both potentiometers with microcontroller ADC inputs.

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Reading serial data from chipKIT UNO32 using Python3 and pyserial

installing python3 - path variable

Python is great programming (scripting) language that is supported on all platforms. Embedded enthusiasts love it because of the variety of modules that connect things to the internet and other crazy stuff by writing only a few code lines. Today my interest was to read serial data using Python 3.3 and the pyserial module. Python 3.3 is still fresh, and there is a majority of modules that need to be ported from Python 2 to Python 3, but I hope soon they will here. The serial module seems to be working fine in Windows 7 x64, and I 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 on your computer. We won’t go into details on how to set up this tool. It is pretty robust. After setup, python install is placed in C:\Python33. To test if things work OK open the command prompt and type python; you should see the python prompt:

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Great method of PCB reverse engineering by using a Photoshop

Rriccibitti has sent us his latest work on reverse engineering of simple keypad circuit. The solution seems to be very simple but effective. He used a digital camera to take a picture of the printed circuit board and a photo editing software to track PCB traces with different colors. OK, for this one, he used Photoshop to have lots of valuable tools that make this work much more manageable. To be more specific, let us see what he’s done:

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Putting your electronics project in an enclosure

Projects that are probably finished and put in an enclosure always catch an eye rather than a PCB prototype with multiple wires showing up. Of course, a project that does its job is fine enough even without a nice shell. But what if you don’t want your board to be exposed. Then put your project in a box. From this point, you need to be an electronics engineer and designer in one. Probably everyone has their own way of putting projects in the boxes, but few tips can save time and nerves. Let’s go through things to keep in mind while looking for boxes and planning necessary tasks: If you have buttons that need to be accessed through the case, find a shallow enclosure or tall controls. If there is a display you want to read but don’t enjoy a big hole in the lid, look for an enclosure with a clear top. If environmental conditions may be a factor, find an enclosure rated for the needs you expect your product to experience. Take a look at these IP ratings. Many manufacturers follow the IP rating system for describing enclosures. Maybe your project has lots of switches or external ports;…

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Encoding and modulation of digital signals

We know that digital signals are stored as binary numbers in memory cells. Let’s see how these digital signals can be transferred, in other words – how they can be encoded into electrical signal shape. When the signal has to be sent, it has to be modulated. Pulse Code Modulation (PCM) Probably the simplest and the most common modulation method is pulse code modulation (PCM). In CPM, coding information is modulated as voltage levels. If the supply voltage is 5V, then binary”1″ is represented as +5V while 0 as 0V level. Only two voltage levels are used to modulate the signal. The signal can be sent in parallel (bus mode) or serial mode. In parallel mode whole (let’s say 8 bit) signal can be sent at once via 8 wires, while in serial mode, data has to be sampled in time. This transmission method is most popular in embedded systems. For instance, ADC sends converted data to DSP using CPM. CPM method is OK, but it has several drawbacks like the number of wires required for parallel buses. Still, probably the most dangerous problem is that transmission may experience skew problems when each data wire may have different time delays…

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Printed Circuit Board (PCB) Technologies

The term circuit technology usually refers to the various techniques used in the manufacture of electrical circuits. A large number of devices that are used today make use of printed circuit boards (PCBs). These devices provide mechanical support for the various components present within the given device and the components’ electrical connections. The electrical connections present on the PCB are made out of copper sheets laminated on a non-conducting material. Initially, a large copper sheet is laminated on the board, and then the sections that are not required are removed. Various techniques are used for the removal of unwanted copper. Some of them are: Silk Screen Printing: In this technique, an etching resistant ink is applied to those required areas, and the remaining part is etched off. Photoengraving: Here, a photomask of the circuit required is prepared using the desired software, and then it is applied onto the blank PCB. After this, the portions that are not required are etched off. PCB Milling: In this technique, a mechanical milling system that can work on 2 or 3 dimensions is used to remove the copper. The milling system is controlled by software. In some other techniques only the required copper is…

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Audio Signal Processing

Processing of audio signals is one of the most important and widely used applications of digital signals processing. It is being used in many fields such as communication, broadcasting audio signals for radios, television etc. It primarily includes analysis of audio signals that fall in the human hearing frequency by mathematical. The audio signals that fall in the human auditory range depend both on physical and psychological factors. A separate branch has been introduced to study the same and is called psychoacoustics. Wherever signals are concerned, one has to deal with two different viz. digital and analogue types. The techniques that are used to deal with these two types of audio signals are different. In analogue audio signals, the pressure transformations are usually represented electrically in the form of voltage levels.

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Batteries and cell characteristics

Batteries are a cheap, small, and relatively safe way of having a portable energy source. There are many types of batteries with different characteristics and uses. Probably many of you heard the terms battery and cell referring to the same. But from a technical perspective, these are different things – a cell is a single unit that houses a single chemical reaction and produces electricity. At the same time, a battery is a pack of cells. Nominal cell voltage and battery voltage For instance, a single AA battery can be called a cell because this is a single unit where a single chemical reaction generates a voltage of 1.5V. Still, car lead-acid battery has six cells producing 2.0V each while all battery produces 12V. The first important thing to remember is that a single cell can produce a specific nominal cell voltage that depends on a chemical reaction. In contrast, the battery voltage is a combined voltage of multiple cells connected in series (or parallel).

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