Tamara Schmitz writes:
Combining the operation of a boost regulator and a negative voltage converter can generate a negative supply from a single low-voltage supply. The circuit in Figure 1 shows a standard application circuit for a +20 V supply along with two op amps, two diodes and two capacitors to generate the – 20 V supply. This article will discuss the basic operation of a boost converter to generate a larger positive supply voltage. Equations are derived to determine the minimum inductor value to maintain a safe peak inductor current, and a maximum inductor value to maintain continuous conduction mode (CCM) operation. The article will then discuss the generation of a negative supply and the restrictions of the design.
Simple Circuit to Generate Plus and Minus Supplies Using a Boost Regulator - [Link]
The wireless modem you’ve been waiting for. Works with Arduino & other micros. Open source mesh networking base. FCC Certified. Cheap. Eric Gnoske writes:
So who’s behind RadioBlocks? A group of engineers who have worked on many aspects of low-power radio devices. A group of engineers who time & time again saw customers coming to us with similar requests, but with no way for us to easily fill them. So we created RadioBlocks to allow people to easily drop a radio link into their project, hence “RadioBlocks” – A simple to use radio building block.
Sure there are lots of radio boards out there. Most have two modes: super-simple serial-port replacement mode, and complex full network mode. Neither of those are useful – most people want to send some data between some devices. They need more than serial-port replacement, but the full network mode is too much hassle. Then many of those radio devices are just too expensive – are you really going to drop $30 or $40 on a single radio node, then buy extra hardware so you can attach sensors? Good luck with that!
RadioBlock: Simple Radio for Arduino or any Embedded System - [Link]
The mPrinter is a small thermal printer that prints dynamic snippets of information we call mPrints. Andy Muldowney writes:
mPrinter – An analog printer for a digital world - [Link]
Don Scansen writes:
For any complete energy-harvesting system designed to provide power to anything but small, short-duration loads, storage batteries represent a necessary but significant portion of the initial expense. The cost of batteries over the lifetime of the system can have an even larger impact if care is not taken to maximize the useful life of the battery component. What’s more, if unit growth continues for photovoltaic and other energy-harvesting systems relying on large-capacity storage batteries, designs that fail to maximize battery life could have a negative environmental impact due to the extra material and energy consumption needed to manufacture replacement systems as well as dispose of exhausted units.
Charge Controller Design for Maximum Battery Lifetime in PV Systems - [Link]
Plastic Water Solenoid Valve – 12V – 1/2 NPT. Control the flow of fluid using the flow of electrons! This liquid valve would make a great addition to your robotic gardening project. There are two 1/2″ (Nominal NPT) outlets. Normally, the valve is closed. When 12VDC is applied to the two terminals, the valve opens and water can push through. The valve has a gasket arrangement inside, so there is a minimum pressure requirement of 0.02 Mpa (3 PSI). Also, liquid can only flow one direction.
Plastic Water Solenoid Valve – 12V - [Link]
Teensy 3.0 is a small, breadboard-friendly development board designed by Paul Stoffregen and PJRC. Teensy 3.0 will bring a low-cost 32 bit ARM Cortex-M4 platform to hobbyists, students and engineers, using Arduino(R)** or programming directly in C language.
Based on a 32 bit ARM chip, Teensy 3.0 aims to greatly increase the computing capability and peripheral features, but maintain the same easy-to-use platform that has made Teensy 2.0 so successful.
Teensy 3.0 has been in development for well over 1 year. Many prototypes have been built. The photo above is the final prototype.
Teensy 3.0 – 32 bit ARM Cortex-M4 - [Link]
The Inebriator – Home made Arduino powered cocktail Machine, dispensing the signature cocktail “The Inebriator”
The Inebriator – Arduino Cocktail Machine - [Link]
Microchip PIC® 8-bit microcontrollers are quite popular amongst hobbyists, and I’ve used them for a long time in several of my projects. They are very cheap, use only 35 assembly instructions that are easy to learn, and most importantly they use flash memory, which gives you the possibility to program the device virtually as many times as you want during your experiments. Up until now I’ve used a simple serial interface and picprog to program them under Linux, but sadly the trend is not to include a serial port anymore on new computers/laptops. Of course there are USB programmers on the market, but quite often their price exceeds 30€ and not all of them work well on Linux. Also a commercial programmer usually supports hundreds of different chips, while all I needed was a simple and cheap way to program, say, the four chips I work with most of the time. So, with the introduction of the Raspberry Pi, and the possibility to control external hardware through its GPIO connector, I thought it would be worth spending some time to design a simple interface and write a software to program some PICs. The result of about a week of work is rpp – a Raspberry Pi PIC Programmer that uses the GPIO connector.
Raspberry Pi PIC Programmer using GPIO - [Link]
A microcontroller-based voltage cutoff circuit, currently in use on several motorcycles. It is designed to monitor the voltage level for the battery, and activate an accessory circuit when the level is sufficiently high. If the level drops below a calibrated level, the accessories are cut off.
Low-Voltage Cutoff Switch - [Link]