Automating your Door for $20

We love the doors on Star Trek’s Enterprise. We should have known they were human-operated though because they were too smart. They would wait for people, or fail to open when someone was thrown against them during a fight. [SieuweE] has a much more practical automatic door that he calls ArduDoor.

You might guess from the name it uses an Arduino. It also uses a windshield wiper motor which is perfect since it is high-torque and low speed. You might even be able to pick one up for little or nothing if you frequent the junkyards.

The downside is that …read more http://pje.fyi/Q9tJPb

Paul Jacob Evans

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Never Let Your Christmas Tree Run Dry, With Added Ultrasound

Winter in the parts of the Northern Hemisphere for which observing Christmas includes bringing half a forest into the house should really be divided into two seasons. No-spruce-needles-in-the-carpet season, and spruce-needles-doggedly-clinging-to-the-carpet season. Evergreen trees were not designed for indoor use, and for a hapless householder to stand any chance of keeping those needles on the branches there has to be a significant amount of attention paid to the level of the water keeping the tree hydrated.

[Evan] has paid that attention to the problem of Christmas tree hydration, and to address the shortcomings of earlier designs has come up with …read more http://pje.fyi/Q5819S

Paul Jacob Evans

Reverse Engineering An Ultrasonic Car Parking Sensor

It has become a common sight, a must-have feature on modern cars, a row of ultrasonic sensors embedded in the rear bumper. They are part of a parking sensor, an aid to drivers for whom depth perception is something of a lottery.

[Haris Andrianakis] replaced the sensor system on hs car, and was intrigued enough by the one he removed to reverse engineer it and probe its workings. He found a surprisingly straightforward set of components, an Atmel processor with a selection of CMOS logic chips and an op-amp. The piezoelectric sensors double as both speaker and microphone, with a …read more http://pje.fyi/P9xpX9

Paul Jacob Evans