Vintage COSMAC Elf is Pretty Close to Original

Popular Electronics was famous for the article introducing the Altair 8800 back in 1975 (well, the cover date was 1975; it really came out in late 1974). That was so popular (no pun intended), that they ran more computer construction articles, including the SWTPC 680 late in 1975. But in 1976 a very popular article ran on building a very simple computer called the COSMAC ELF. [Youtubba] had an Altair, but always wanted a “cute” COSMAC ELF. Now, forty-something years later, he finally got around to it. He made the very detailed video about his experience, below.

Surprisingly, he didn’t have to look very hard for too many of the components as most of them were available from Digikey. He had to get compatible RAM chips, the 1802 CPU and LED displays. He also couldn’t find a look-alike crystal, so he used a fake one and a hidden oscillator. The result looks awfully close to the original. He even did a nice front panel using Front Panel Express.

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Banana Phone Blocks Robocalls

Despite the implementation of the National Do Not Call Registry in the US (and similar programs in other countries), many robocallers still manage to get around the system. Whether they’re operating outside the law somehow (or they simply don’t care about it) there are some ways you can take action to keep these annoying calls from coming through. [Alex] is among those to take matters into his own hands and built a specialty robocall-blocking device.

Based on a Raspberry Pi, the “Banana Phone” is able to intercept incoming calls on standard land lines or VoIP phones. After playing a short message, the caller is asked to input a four-digit code. Once the code is correctly entered, the caller is presumed to be human, added to a whitelist, and then the Pi passes them on to the recipient. There are, however, some legitimate robocallers such as emergency services regarding natural disasters or utility companies regarding outages. For these there is a global whitelist that the Pi checks against and forwards these robocalls on to the recipient automatically.

This project was originally an entry into a contest that the Federal Trade Commission put on a few years ago for ideas about how to defend against robocalls. We covered it back then, but now there are full build instructions. Even though the contest is long over, the Banana Phone is still in active development so if you have a spare Pi lying around you can still set this up yourself. There are some other interesting ways to defend against robocalls as well, like including the “line disconnected” tone in your voicemail, for example.

How To Telepathically Tell A Robot It Screwed Up

Training machines to effectively complete tasks is an ongoing area of research. This can be done in a variety of ways, from complex programming interfaces, to systems that understand commands in natural langauge. A team from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) wanted to see if it was possible for humans to communicate more directly when training a robot. Their system allows a user to correct a robot’s actions using only their brain.

The concept is simple – using an EEG cap to detect brainwaves, the system measures a special type of brain signals called “error-related potentials”. Simply noticing the robot making a mistake allows the robot to correct itself, and for a nice extra touch – blush in embarassment.

This interface allows for a very intuitive way of working with a robot – upon noticing a mistake, the robot is able to automatically stop or correct its behaviour. Currently the system is only capable of being used for very simple tasks – the video shows the robot sorting objects of two types into corresponding bins. The robot knows that if the human has detected an error, it must simply place the object in the other bin. Further research seeks to expand the possibilities of using this automatic brainwave feedback to train robots for more complex tasks. You can read the research paper here.

MIT’s CSAIL work on lots of exciting projects – their video microphone technology is truly astounding.

[Thanks to Adam Connor-Simmons for the tip!]

Soda Bicarb Diode Steering Circuit For 7-Segment Display

[Hales] has been on a mission for a while to make his own diodes and put them to use and now he’s succeeded with diodes made of sodium bicarbonate and water, aluminum tape and soldered copper. By combining 49 of them he’s put together a soda bicarb diode steering circuit for a 7-segment display capable of showing the digits 0 to 9.

He takes the idea for his diode from electrolytic capacitors. A simple DIY electrolytic capacitor has an aluminum sheet immersed in a liquid electrolyte. The aluminum and the conductive electrolyte are the two capacitor plates. The dielectric is an aluminum oxide layer that forms on the aluminum when the correct polarity is applied, preventing current flow. But if you reverse polarity, that oxide layer breaks down and current flows. To [Hales] this sounded like it could also act as a diode and so he went to work doing plenty of experiments and refinements until he was confident he had something that worked fairly well.

In the end he came up with a diode that starts with a copper base covered in solder to protect the copper from his sodium bicarbonate and water electrolyte. A piece of aluminum tape goes on top of that but is electrically insulated from it. Then the electrolyte is dabbed on such that it’s partly on the solder and partly on the aluminum tape. The oxide forms between the electrolyte and the aluminum, providing the diode’s junction. Connections are made to the soldered copper and to the aluminum.

To truly try it out he put together a steering circuit for a seven segment display. For that he made a matrix of his diodes. The matrix has seven columns, one for each segment on the display. Then there are ten rows, one for each digit from 0 to 9. The number 1, for example, needs only two segments to light up, and so for the row representing 1, there are only two diodes, i.e. two dabs of electrolyte where the rows overlap the columns for the desired segments. The columns are permanently wired to their segments so the final connection need only be made by energizing the appropriate row of diodes. You can see [Hales] demonstrating this in the video below the break.

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Another Day, Another “IoT” Backdoor

As if you needed any reason other than “just for the heck of it” to hack into a gadget that you own, it looks like nearly all of the GSM-to-IP bridge devices make by DBLTek have a remotely accessible “secret” backdoor account built in. We got sent the link via Slashdot which in turn linked to this story on Techradar. Both include the scare-words “Chinese” and “IoT”, although the devices seem to be aimed at small businesses, but everything’s “IoT” these days, right?

What is scary, however, is that the backdoor isn’t just a sloppy debug account left in, but rather only accessible through an elaborate and custom login protocol. Worse still, when the company was contacted about the backdoor account, they “fixed” the problem not by removing the account, but by making the “secret” login procedure a few steps more complicated. Which is to say, they haven’t fixed the problem at all.

This issue was picked up by security firm Trustwave, but they can’t check out every device on the market all the time. We may be preaching to the choir here, but if you’re ever wondering why it’s important to be able to break into stuff that you own, here’s another reminder.

What Voltage for the All-DC House?

The war of the currents was fairly decisively won by AC. After all, whether you’ve got 110 V or 230 V coming out of your wall sockets, 50 Hz or 60 Hz, the whole world agrees that the frequency of oscillation should be strictly greater than zero. Technically, AC won out because of three intertwined facts. It was more economical to have a few big power plants rather than hundreds of thousands of tiny ones. This meant that power had to be transmitted over relatively long distances, which calls for higher voltages. And at the time, the AC transformer was the only way viable to step up and down voltages.

acdc
No, not that AC/DC

But that was then. We’re right now on the cusp of a power-generation revolution, at least if you believe the solar energy aficionados. And this means two things: local power that’s originally generated as DC. And that completely undoes two of the three factors in AC’s favor. (And efficient DC-DC converters kill the transformer.) No, we don’t think that there’s going to be a switch overnight, but we wouldn’t be surprised if it became more and more common to have two home electrical systems — one remote high-voltage AC provided by the utilities, and one locally generated low-voltage DC.

Why? Because most devices these days use low-voltage DC, with the notable exception of some big appliances. Batteries store DC. If more and more homes have some local DC generation capability, it stops making sense to convert the local DC to AC just to plug in a wall wart and convert it back to DC again. Hackaday’s [Jenny List] sidestepped a lot of this setup and went straight for the punchline in her article “Where’s my low-voltage DC wall socket?” and proposed a few solutions for the physical interconnects. But we’d like to back it up for a minute. When the low-voltage DC revolution comes, what voltage is it going to be?

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Los Angeles Hackaday Unconference Happening on 3/18

Reserve your spot at the Los Angeles Hackaday Unconference on Saturday, March 18th. The Hackaday community is huge in LA and this event will fill up, so don’t delay.

The Unconference is a unique opportunity to decide the course of the day as it happens. Everyone who attends should be ready to stand and deliver at least eight minutes on a topic they find exciting right now. The energy this creates is the key to a level of involvement that can’t be matched at traditional conferences that have a divide between those presenting and those attending.

LA Joins Chicago and San Francisco

This announcement of the Los Angeles Hackaday Unconference joins two others happening the same day. Last week we announced San Francisco as a host location and the event is now full… but anyone in the area should still get their name on the waiting list. Four days ago we announced Chicago as the second location and that event will likely reach capacity today. [Shulie Tornel] and [Jasmine Brackett] are organizing things at the LA event which is being held at the Supplyframe Design Lab from 1 – 8 pm on 3/18.

Build Something that Matters

You can speak on any topic you want, but sometimes having a theme helps to get the ideas flowing. When considering your topic, keep Build Something that Matters in mind. Have you been looking into a technology, project, or idea that can make life a little (or a lot) better for the world? That would be an exquisite topic.

At the beginning of the day we’ll go around the room and get the talk title or subject from everyone there, then as a group we’ll hammer out a schedule for the day. As presentations progress, we encourage new impromptu talks to spring up, and can even split those off into a second talk space or discussion group. We’ll have food and drink on hand, as well as some interesting hardware to give out as door prizes.

The Hackaday Unconference is the ultimate idea and energy exchange in a crowd of your peers. You’ll have a hard time finding a cooler way to spend a Saturday this year. See you there!