I had lunch with a fellow electronics enthusiast on his return from a trip with his daughter in search of a college of engineering. He was blown away by the level of electronic automation in many of the campuses they visited. Not only was there ubiquitous Wi-Fi, but at several colleges, smartphone-toting students could monitor the status of the washing machines and dryers in each of the dorms. Tablet-sized LCD panels affixed to classroom doors announced activities in that room for the day, and numerous PC kiosks enabled students to check their email or class schedule. My friend’s daughter wasn’t as impressed with the modern electronic accoutrements, but instead expected what they found and more. Perhaps this explained my friend’s frustration with trying to teach his daughter the ”old fashioned” electronics of resistors, transistors, and other discrete components. With sights set on creating a startup company using mobile computing, she couldn’t see the relevance learning to flip a few LEDs on and off with a complex circuit or of building a power supply from scratch when a single chip would do the job.
The new PR4404 from PREMA Semiconductor is a LED driver providing more than 150mA out of one battery cell and up to 300mA from two batteries for one to three power LEDs. A hold input allows controlling the LED brightness via a PWM signal or switching the LED from a microcontroller.
Questions on a synthesis circuit, IC chips, grounding problems, resistor values (for light/dark), power supplies, and Kodak photoresist and developer are answered. Read More...