74hc240

2 Articles

Solar Circuit Sculpture Pumms The Night Away

April 4, 2019 by 17 Comments

A word of warning: Google for the definition of the word “pummer” at your own risk. Rest assured that this beautiful solar-powered circuit sculpture fits the only definition of pummer that we care to deal with.

For the unfamiliar, a pummer is a device from the BEAM style of robotics, a sort of cyborg plant that absorbs solar energy during the day and turns it into a gently pulsating light that “pumms” away the dark hours.

[Mohit Bhoite]’s take on the pummer is an extraordinary model of a satellite executed mainly in brass rod. His attention to detail on the framework boggles our minds; we could work for days on a brass rod and never achieve the straight lines and perfect corners he did. The wings support two solar cells, while the hull of the satellite holds a dead-bugged 74HC240 octal buffer/line-driver chip and all the other pumm-enabling components. A one farad supercap – mounted to look like a dish antenna – is charged during the day and a single LED beacon blinks into the night.

No schematic is provided, but there are probably enough closeup shots to reverse engineer this, which actually sounds like a fun exercise. (Or you can cheat and fetch the PDF copy of the old Make magazine article that inspired him.)

Hats off to [Mohit] for a top-notch circuit sculpture. We’ve seen similarly detailed and well-executed sculptures from him before; something tells us this won’t be the last.

Thanks to [Varun Reddy] for the tip.

200 Mile RF Transmitter (and High Altitude Balloon)

July 27, 2010 by 48 Comments

If there is one thing we like, it’s a fellow hacker so enthusiastic about his or her work that they write the article practically for us by including as much detail and information as possible.

In this two part hack, [Scott] wrote in to let us know not only about a high school built high altitude balloon, but also his $5 long range RF transmitter. The former is simply GPS and video data logged over the flight, but [Scott’s] specialty comes in the latter. A 74HC240 octal buffer is using to amplify the signal (Morse code) from an ATTiny44a with a 29MHz oscillator, producing a usable signal as far away as 200 miles.

It is low bandwidth, but if you’re looking for a simple transmitter in your project and need something with more power (and a smaller package), this might be the ticket.