MSP430 Launchpad from Texas Instruments is one of the cheapest microcontroller development boards (4.30 $), but it was lacking a free IDE (I mean free as in freedom, not as in free beer). Now there is Energia, an Arduino-like IDE for MSP430 Launchpad, which makes it easy to get started, no matter the technical level of the user.
What would you say about 25$ single board computer ? Now it has become a reality with Raspberry Pi, a low ARM GNU/Linux box.
It has a quite impressive set of features considering its price. It’s based on BCM2835 SoC which contains a 700 MHz ARM processor and a Videocore 4 GPU capable of HD video
The most popular hobby electronics platforms usually work at 5 V, but many times you need to interface your circuit with a high-end sensor which works at a lower voltage (ex. 3.3 V). It is quite easy to design your own low cost voltage level translators, using only discrete components.
This is an easy once, since it can be done only with passive components. The easiest high to low voltage level translator is a resistor divider.
Since \(R_1\) and \(R_2\) form a resistor divider, the output voltage is only a fraction of the input voltage:
A few years ago it was expensive and almost impossible to manufacture custom mechanical parts at home. Recently we have seen the rise of the low cost 3D printers (usually under 1000 $), allowing you to have your own factory at home.
In the last period, the software defined radio starts to become more and more popular, due to it’s obvious advantages over the analog radio. With SDR, basically you can do almost everything, no matter how complicated the modulation and demodulation techniques are used.
This concept is not new, but the high performance electronics available for low prices have rendered practical many things. Now, it costs only 20$ !