by Peter Demchenko @ edn.com:
Low-current switching regulator ICs often use a Darlington as the output switch. The power conversion efficiency in this case can be improved with the help of only two cheap components. To make this possible, the chip should have a separate pin for the collector of the driver transistor Q1 (Figure 1). At startup, D1 forms a path for the collector current of Q1. Later, D1 and C1 comprise a current-additive rectifier which enhances the collector voltage and current of Q1, hence reducing voltage drop on the closed switch Q2.
Improve efficiency of low-cost switcher - [Link]
Simon has created an servo switcher for use on autonomous vehicles. designed to allow manual control if the autonomous controller fails. Using a pic12f683 and 4066 analog switch. source code and board files are available on his website.
Autonomous servo switcher – [Link]
The LM2267x/LM22680 Simple Switcher Step-Down Regulator Series is the next generation of highly popular LM267x Simple Switcher Regulators. Numerous enhancements and improvements have been added such as an input range down to 4.5V, tighter output accuracy, adjustable switching frequency, a precision enable, and thermally enhanced green packages.
LM2267x/LM22680 Simple Switcher Series - [Link]
Video switcher allows monitoring up to 4 security video cameras. Interesting thing is that device uses intelligent method of motion detection. PIC grabs low resolution (8×8) video frames and then calculates numeric sums of screen regions to detect motion by detecting image changes.
Of course it may seem that PIC microcontrollers are too slow for taking frame or even single video line at once. So it reads one sample per video line while line skewing has no practical difference. This way it collects all 64 data points. The Source File only implements the 4 cameras. You can connect any number from 1 to 4 and the software will sort out the detection and switching. Motion on any video input switches the output immediately to that source. [via]
Video camera switcher with motion detection - [Link]