An Ugly but Functional Pi Laptop

It’s got a face only its mother could love. Or a Hackaday writer, since this ugly e-waste laptop proudly sports a Jolly Wrencher on its back.

All joking aside, this is a great example of doing what you can with what you’ve got. [starhawk] is limited on funds, and a regular laptop is beyond his means. But being light in the wallet is no reason to go without when you can scrounge parts from friends and family. The base of the laptop is a mini USB keyboard, with the top formed mainly by a 7″ HDMI panel. The back of the display is adorned with a Raspberry Pi 3, a USB hub, a little sound dongle, and the aforementioned Jolly Wrencher. The whole thing is powered by a cast-off power supply brick — no exploding batteries to worry about!

Other Pi-based laptops we’ve covered may be sleeker, but we’ve got to admit that [starhawk]’s keyboard is probably the better choice for working on the next great American novel. And a Linux laptop for next to nothing? That’s a win in our book.

Pulse Oximeter is a Lot of Work

These days we are a little spoiled. There are many sensors you can grab, hook up to your favorite microcontroller, load up some simple library code, and you are in business. When [Raivis] got a MAX30100 pulse oximeter breakout board, he thought it would go like that. It didn’t. He found it takes a lot of processing to get useful results out of the device. Lucky for us he wrote it all down with Arduino code to match.

A pulse oximeter measures both your pulse and the oxygen saturation in your blood. You’ve probably had one of these on your finger or earlobe at the doctor’s office or a hospital. Traditionally, they consist of a red LED and an IR LED. A detector measures how much of each light makes it through and the ratio of those two quantities relates to the amount of oxygen in your blood. We can’t imagine how [Karl Matthes] came up with using red and green light back in 1935, and how [Takuo Aoyagi] (who, along with [Michio Kishi]) figured out the IR and red light part.

The MAX30100 manages to alternate the two LEDs, regulate their brightness, filter line noise out of the readings, and some other tasks. It stores the data in a buffer. The trick is: how do you interpret that buffer? Continue reading “Pulse Oximeter is a Lot of Work”

3D Print Your Next Dwelling In A Day

What’s the shortest amount of time in which a 400 square foot home can be built? A few weeks? Try a fully printed structure in 24 hours for a little over $10,000.

This radial residence was materialized out of concrete in Stupino, Russia by [Apis Cor], and six collaborating companies, as a prototype. As opposed to traditional — such as it is for tech largely in its infancy — assembly of pre-printed or fabricated pieces, the building was printed as a whole, with the printer removed by crane before finishing the rest of the construction. It features a bathroom, hallway, living room, and a compact kitchen — everything a bachelor or bachelorette needs.

Continue reading “3D Print Your Next Dwelling In A Day”

So Long, and Thanks for all the Crystals

There was a time when anyone involved with radio transmitting — ham operators, CB’ers, scanner enthusiasts, or remote control model fans — had a collection of crystals. Before frequency synthesis, became popular, this was the best way to set an accurate frequency. At one time, these were commonly available, and there were many places to order custom cut crystals.

One of the best-known US manufacturers of quartz crystals still around is International Crystal Manufacturing (ICM). Well, that is, until now. ICM recently announced they were ceasing operations after 66 years. They expect to completely shut down by May.

In a letter on their website, Royden Freeland Jr. (the founder’s son), committed to fulfilling existing orders and possibly taking some new orders, raw materials permitting. The company started making products out of Freeland’s father’s garage in 1950.

Another big name that might still be around is Jan Crystals. We say might, because although their website is live, there’s not much there and the phone number is not quite disconnected but it is “parked.” There are also some posts on the Internet (where everything is true) indicating they are out of business.

Even if you didn’t do radio work, crystals are a staple in digital systems where an accurate clock is necessary and some types of filters, too. Of course, you can still get them, you just may not be able to get them made in the United States soon.

If you want to know more about the technology behind crystals [Jenny] has you covered. Crystals are one of those things that have not changed much in a long time, so you might enjoy the very 1960’s vintage U. S. Air Force training film below.

Continue reading “So Long, and Thanks for all the Crystals”

Automatic Deploying Lightning Rod

As hackers, hams, and builders of all sorts of things that go in our yards or are attached to our houses we often encounter resistance from building associations and by-laws regarding what to us are harmless necessities but to others are risks to their sight-lines, property values, or are seen as safety hazards. A student at the Bergen County Academies Mechatronics Research Lab has identified this same issue with lightning rods for homes, monuments, and buildings of fine architecture; people don’t want to add unsightly lightning rods despite their proven protections. Her solution? Detect when a storm is approaching and automatically deploy the lightning rod for the duration of the storm.

To detect the approaching storm she’s monitoring the changing barometric pressure using an Adafruit BMP085 barometric pressure, temperature and altitude sensor (now replaced by the BME280) connected to an Arduino with a motor shield. If the pressure is low and the trend has been decreasing then she pivots the lightning rod up using a motor salvaged from a satellite dish. When the risk abates, she pivots the rod back down again. Admittedly the lightning rod has yet to be attached and care will have to be taken with how the discharge cable is deployed but it’s a start. You can see it in action in the video below.

Continue reading “Automatic Deploying Lightning Rod”

Tea for Two: A Tiny Tea Timer

The ATtiny85 microcontroller doesn’t have all that much of anything: 8 KB of flash, an 8-bit architecture, and only eight pins (three of which are taken up with power and reset duties). And that’s exactly what makes it a great fit for tiny little projects.

[Mimile]’s Tea Timer has a switch, a button, eight LEDs, and a buzzer. Flip the switch to “set” and button presses run through the desired steeping times. Flip it to “run” and you’re timing. The LEDs blink and the buzzer plays “Tea for Two” in squawky square waves. Wonderful!

But wait, how to control all of this I/O with just five pins? With one pin each for the two switches and one for the buzzer, that leaves only two pins for the eight LED display. [Mimile]’s fun solution is to use a binary counter (a 74HC393) and the remaining two lines to count and reset. That means toggling a pin very fast 255 times to light up all the LEDs. That’s a bizarre way to go, but we like it!

Hackaday has proven unable to resist the siren song of the ATtiny85. Whether teaching it to swear, to speak I2C, or to transmit analog TV signals, there’s just something about this cute little chip that invites you to test your mettle.

A Clock Created with Conway’s Life

Conway’s life has to be the most enduring zero-player computer game in history. Four simple cellular automaton rules have been used to create amazing simulations since the 1970’s. The latest is an entire digital clock implemented in life. StackExchange user [dim] created this simulation in response to a challenge from [Joe Z]. We have to admit that we didn’t believe it at first, but you can run it yourself by importing [dim’s] gist to the online Javascript Conway’s Life Simulator. To say this is impressive would be an understatement. We don’t know exactly how long it took [dim] to build this clock, but the challenge has been around since August of 2016.

[Dim] does a pretty good job of describing exactly how the clock works. The timebase is at the top. Below it is clock distribution and counters. After that come counters, latches, and lookup tables. Data moves around the clock in the form of gliders. P30 (aka Queen Bee) gliders to be exact. It might make things simpler to think of the glider paths as circuit traces, and the gliders themselves as clock pulses.

We couldn’t get over all the little details in this design. If you zoom way in, you can see all the lookup table patterns have been annotated, much in the way a schematic would be. For [Dim’s] next feat, we hope he takes on [Joe Z’s] Tetris challenge!

Conway’s life is like honey for hackers. We’ve seen it running on our own Hackaday Badge. We’ve even seen clocks that run the game on their display. Someone needs to implement a clock that runs the game that runs this clock. Clockception, anyone?