Analysis of the bipolar transistor amplifier at low-frequency is relatively easy, and several calculators exist online that do a good job. For high-frequency operation, there are fewer references available. For my projects, I like to build a reference spreadhseet where everything is in one place. This allows me more flexibility in optimizing the circuit, and is much faster than simulating with LTSpice or similar package. Furthermore, constructing such a tool is a great way of gaining more insight into how the circuit works, and how each of the parameters affects performance.
Common-Emitter and Common-Collector Transistor Amplifier Calculator for High-frequency Operation - [Link]
by Boris Landoni:
This robot will mow the grass of your garden, staying within a defined area, avoiding all obstacles and working in complete autonomy, automatically charging itself with a solar panel.
In this post we present a robotic lawn mower, powered with solar energy and able to operate just with the clean energy from the sun; this one is a great difference from the commercial projects having a robot in need of a charging station connected to the electrical grid.
A Robotic lawn mower powered by Solar Energy with an Arduino heart - [Link]
A primer app note(PDF) on silicon transient voltage suppressors by Microsemi.
Silicon transient voltage suppressors (TVSs) are clamping devices that limit voltage spikes by low impedance avalanche breakdown of a rugged silicon pn jucntion. They are used to protect sensitive components from electrical overstress such as that caused by induced lightning, inductive load switching and electrostatic discharge.
App note: What is a silicon transient voltage suppressor and how does it work - [Link]
An application note from Texas Instruments, white LED driver with digital and PWM brightness control (PDF!):
With a 40-V rated integrated switch FET, the TPS61160/1 is a boost converter that drives LEDs in series. The boost converter runs at 600kHz fixed switching frequency to reduce output ripple, improve conversion efficiency, and allows for the use of small external components.
The default white LED current is set with the external sensor resistor Rset, and the feedback voltage is regulated to 200mV, as shown in the typical application. During the operation, the LED current can be controlled using the 1-wire digital interface ( Easyscale™ protocol) through the CTRL pin.
App note: White LED driver with digital and PWM brightness control - [Link]
High efficiency, low standby power consumption and a power reserve, all this can be gained with a new adapter from our portfolio.
Minwa NR120P150PGS/E+ is in fact an “ordinary“ adapter with a fixed output voltage 12VDC/1500 mA. But it´s worth to mention, that it meets everything, what we usually require from a modern mains adapter:
- modern design (SMPS)
- high efficiency
- low standby power consumption (<0.3W)
- meets all latest regulations – EuP2, ErP,…
And finally a bonus – outstanding price. Adapters from company Minwa are in general always price-affordable, but here it is even more obvious. When we compare a one level weaker adapter NK120P100PGS/E+ (12V/1000 mA) with NR120P150PGS/E+ we´ll find, that for the price higher +14% (already at purchase of one piece) we´ll gain +50% power. So if you have a device requiring up to 1.5A current, or you use a 1A adapter at almost 100% and you want to gain some power reserve and probably a longer lifetime of an adapter, you can do so with minimum expenses.
Plus 50% of power for a scant one Euro? - [Link]
Linear Technology has recently announced an addition to its family of power regulator solutions. The LTC3622 is a dual step-down regulator in a small 3 x 4 mm package providing two independently configurable 1 A outputs operating from a 2.7 to 17 V input. External voltage divider networks define the two output voltages or alternatively a range of fixed output voltage versions result in a lower component count. The input voltage range makes it suitable for operation from single or multiple lithium cells or from a vehicular supply.
New Dual step-down Regulator - [Link]
Paul over at DorkbotPDX writes:
For the last several weeks, I’ve been working on SPI transactions for Arduino’s SPI library, to solve conflicts that sometimes occur between multiple SPI devices when using SPI from interrupts and/or different SPI settings.
To explain, a picture is worth 1000 works. In this screenshot, loop() repetitively sends 2 bytes, where green is its chip select and red is the SPI clock. Blue is the interrupt signal (rising edge) from a wireless module. In this test, the interrupt happens at just the worst moment, during the first byte while loop() is using the SPI bus!
Without transactions, the wireless lib interrupt would immediately assert (active low) the yellow chip select while the green is still active low, then begin sending its data with both devices listening!
SPI Transactions in Arduino - [Link]
We have already seen a number of ideas for tracking tags seeking funds on Kickstarter, most systems are limited by the range of Bluetooth communication with a smart device. This system from Iotera tackles the problem using cloud-based thinking: The basic wireless system consists of one or more tags or ‘iotas’ and a home base unit. Each 22 x 11 x 3 mm iota contains a chip, accelerometer, temperature sensor, speaker, RF transceiver, Bluetooth (unused so far) and a battery to give up to three months operation. Each iota communicates with the home base unit using wireless channels in the 902 to 928 MHz band giving a range of up to four-miles. Back home, the base unit receives the low-speed transmissions from the iota tag and forwards the information to a server via a Wi-Fi connection.
Novel Cloud-based Tag System - [Link]
Touring factories in Shenzhen: Visiting an assembly line, Seeedstudio and a CNC shop
Shenzhen is the geek’s paradise and can be described as an awesome concentration of very different companies, all within an hour cab ride from your hotel. If you ever go there, I highly recommend you to have a look at Ian’s article to get practical informations. Shenzhen is located in the south of China, right next to the border with Hong Kong. I therefore decided to spend my first day in this former British colony to buy myself a nice camera to bring back cool videos of my adventures.
Touring in Shenzhen video series from Limpkin - [Link]
Learn how to create your own low cost wireless sensors and connect them to the world.
Store your sensor data at home or in our cloud. We provide fancy graphs and other great online tools to help you manage and analyze your sensor data!
mysensors.org – Learn how to create your own low cost wireless sensors - [Link]