A Tube AM Transmitter In A Soup Can

May 28, 2017 by Jenny List 23 Comments

A standard early electronics project or kit has for many years been the construction of a small broadcast transmitter with enough power to reach the immediate area, but no further. These days that will almost certainly mean an FM broadcast band transmitter, but in earlier decades it might also have been for the AM broadcast band instead.

The construction of a small AM transmitter presents some interesting problems for an electronic designer. It is extremely easy to make an AM transmitter with a single transistor or tube, but it is rather more difficult to make a good one. The modulation has to be linear across the whole amplitude range, and its effect must not pull the frequency of the oscillator and cause FM distortion.

It’s a task [Joe Sousa] has tackled, with his one tube AM transmitter in a Campbell’s soup can. His write-up of the transmitter contains a full description of the problems he faced, and how his design overcomes them. His oscillator is a cathode follower, with the tube biased in class A mode to ensure as undistorted a sine wave oscillation as possible. Modulation is provided through the suppressor grid of the pentode tube he’s using.

The completed transmitter is mounted inside the iconic soup can, with the mains transformer mounted on a removable bottom plate. There is a provision for both loop and wire antennas to be connected.

It is probable that this transmitter falls under the so-called “Part 15” rules for unlicenced low-power broadcasting in the USA, however it should be borne in mind that not every territory has this provision. If you build this transmitter, make sure you’re not going to attract the interest of your local equivalent of the FCC.

This article should have whetted your appetite for tiny broadcast transmitters. How about comparing the one here with a full-sized model?

Thanks [2ftg] for the tip.

Hackaday Links: May 28, 2017

May 28, 2017 by Brian Benchoff 46 Comments

Boeing and DARPA are building a spaceplane. Right now it’s only a press release and a few concept images, but it looks like this is an air-launched system kind of like a Tristar/Pegasus, only much higher and completely unmanned. It’s a ton and a half to low earth orbit, with a goal of 10 flights in 10 days.

Up in Albany? There’s a new hacker con happening in a few weeks. Anycon is a hacking, infosec, and cyber security conference happening June 16 & 17th in Albany, NY. The organizers of this con ([Chris], and his company Leet Cybersecurity) are loosely modeling this con after Derbycon. [Dave Kennedy] of TrustedSec will be attending as the keynote speaker.

GOOD NEWS! [Casey Neistat] is under investigation by the FAA. [Casey Neistat] is the YouTuber that flies drones right in the middle of the Hudson River corridor, and is a menace to general aviation around NYC.

This is neat. The Supplyframe Design Lab is the Hackaday Mothership right in the middle of Pasadena where we host our designers in residence, host a few meetups, and slowly fill every cubic inch of space with either dust or tools. The Design Lab just won a design award. You can check out the ‘design’ part of the Design Lab here, but keep in mind it will never be that clean ever again.

Here’s an interesting Twitter to follow. Alitronik is a curator of the weird and wonderful cheap crap that can be found on AliExpress. Need an Altera Cyclone dev board? Here you go. A desk-mountable OLED inspection microscope? Done. A seven dollar Tesla coil? Dude, you can totally fit this inside a hat.

[Drygol] had a nice old Commodore C16 with a broken TED chip. A shame, really. He did what anyone would do: put a C64 motherboard in the case for a fancy stealth upgrade.

Is the great crowdfunded 3D printer boom over? Some would say that ship sailed after dozens of 3D printer crowdfunding projects failed to deliver, or delivered very low-quality machines. These people were wrong. This Polaroid-branded 3D printing pen might not get funding. A year ago, this project would have been funded on day one. There would have been writeups in The Verge on how Polaroid is turning the corner after decades of wasted opportunities. Now, the Crowdfunded 3D printer boom is finally over.

The Hackaday crew was at the Bay Area Maker Faire last weekend and holy crap did we have a blast. Everyone came to the meetup on Saturday except for the fire marshall. The secret OSHPark bringahack on Sunday was even more impressive. We also saw a Donkey Car capable of driving around a track autonomously, but the team behind it didn’t have their work up on the Internet at the time.

Hackaday Prize Entry: ESP32 Monster And Getting Started Quickly

May 28, 2017 by Elliot Williams 19 Comments

Prolific hacker [kodera2t] is working on his own “ESP32 monster board” dev board for the still-newish ESP32 WiFi module. His board has everything: Ethernet, OLED, LiPo, and even CAN-bus. But all that peripheral connectivity is worth nothing if you can’t program the microcontroller to use it.

The Arduino environment for the ESP32 is coming along quite nicely, but it’s not yet fully featured enough to run all of [kodera2t]’s hardware. To take advantage of all that, he needs to use Espressif’s SDK — called the “IoT Development Framework” or IDF for short. In his latest project log, [kodera2t] goes through everything necessary to get the IDF up and compiling on OSX. (It’s strangely similar to the Linux procedure.) Read through the official instructions here, if you want more, but we think [kodera2t] hits all the high points.

While we’re tooting [kodera2t]’s horn, check out his old project — an Arduino shoehorned into an SD card — or watch his alter-ego [Toshiro Kodera] give a serious talk about his day job, engineering radio-frequency meta-materials.

IMSAI 8080 Resurrection

May 28, 2017 by Al Williams 76 Comments

When MITS introduced the Altair 8800–about 43 years ago–it spawned the first personal computer clone: the IMSAI 8080. The clone had several improvements and MITS had difficulty filling orders for real Altairs, so they sold pretty well. [IMSAI Guy] has one of these vintage computers that has been in storage for over 30 years. He’s restoring the thing and there are 26 (and counting) videos of his progress. You can see the second video below, but be sure to check out the others, too.

The IMSAI is famous for being in the movie Wargames. We miss computers with switches and LEDs on a working front panel.

Continue reading “IMSAI 8080 Resurrection” →

A Flying, Fetching, Helping-Hand Omnicopter

May 28, 2017 by Steven Dufresne 26 Comments

Wouldn’t it be nice if you had a flying machine that could maneuver in any direction while rotating around any axis while maintaining both thrust and torque? Attach a robot arm and the machine could position itself anywhere and move objects around as needed. [Dario Brescianini] and [Raffaello D’Andrea] of the Institute for Dynamic Systems and Control at ETH Zurich, have come up with their Omnicopter that does just that using eight rotors in configurations that give it six degrees of freedom. Oh, and it plays fetch, as shown in the first video below.

Each propeller is reversible to provide thrust in either direction. Also on the vehicle itself is a PX4FMU Pixhawk flight computer, eight motors and motor controllers, a four-cell 1800 mAh LiPo battery, and communication radios. Radio communication is necessary because the calculations for the position and outer attitude are done on a desktop computer, which then sends the desired force and angular rates to the vehicle. The desktop computer knows the vehicle’s position and orientation because they fly it in the Flying Machine Arena, a large room at ETH Zurich with an infrared motion-capture system.

The result is a bit eerie to watch as if gravity doesn’t apply to the Omnicopter. The flying machine can be just plain playful, as you can see in the first video below where it plays fetch by using an attached net to catch a ball. When returning the ball, it actually rotates the net to dump the ball into the thrower’s hand. But you can see that in the video.

Continue reading “A Flying, Fetching, Helping-Hand Omnicopter” →

Procedurally Generating Random Medieval Cities

May 28, 2017 by John Baichtal 17 Comments

With procedural content generation, you build data algorithmically rather than manually — think Minecraft worlds, replete with all the terrains and mobs you’d expect, but distributed differently for every seed. A lot of games use algorithms similarly to generate appropriate treasure and monsters based on the level of the character.

Game developer [Oleg Dolya] built a random city generator that creates excellently tangled maps. You select what size you want, and the application does the rest, filling in each ward with random buildings. The software also determines the purpose of each ward, so the slum doesn’t have a bunch of huge mansions, but instead sports a tangle of tiny huts. [Oleg] shows a little of how the application works, using polygons created with the guard towers serving as vertices. You can learn more about the project on Reddit.

As new as this project is, it’s limited. All the maps feature a walled community, each has one castle within a bailey, and none of the cities includes a river or ocean port. [Oleg] designed it to make cool-looking maps, not necessarily accurate or historically realistic ones. That said, he’s already tweaked the code to reduce the number of triangular buildings. Next up, he wants to generate shanty towns outside the city walls.

Head-Up Display Augments Bionic Turtle’s Reality

May 28, 2017 by Dan Maloney 7 Comments

There’s a harsh truth underlying all robotic research: compared to evolution, we suck at making things move. Nature has a couple billion years of practice making things that can slide, hop, fly, swim and run, so why not leverage those platforms? That’s the idea behind this turtle with a navigation robot strapped to its back.

This reminds us somewhat of an alternative universe sci-fi story by S.M. Stirling called The Sky People. In the story, Venus is teeming with dinosaurs that Terran colonists use as beasts of burden with brain implants that stimulate pleasure centers to control them. While the team led by [Phill Seung-Lee] at the Korean Advanced Institute of Science and Technology isn’t likely to get as much work from the red-eared slider turtle as the colonists in the story got from their bionic dinosaurs, there’s still plenty to learn from a setup like this. Using what amounts to a head-up display for the turtle in the form of a strip of LEDs, along with a food dispenser for positive reinforcement, the bionic terrapin is trained to associate food with the flashing LEDs. The LEDs are then used as cues as the turtle navigates between waypoints in a tank. Sadly, the full article is behind a paywall, but the video below gives you a taste of the gripping action.

Looking for something between amphibian and fictional dinosaurs to play mind games with? Why not make your best friend bionic? Continue reading “Head-Up Display Augments Bionic Turtle’s Reality” →