Author: Bryan Cockfield

1852 Articles

Chaotic Oscillator From Antique Logic

June 23, 2020 by 35 Comments

While working on recreating an “ancient” (read: 60-year-old) logic circuit type known as resistor-transistor logic, [Tim] stumbled across a circuit with an unexpected oscillation. The oscillation appeared to be random and had a wide range of frequency values. Not one to miss out on a serendipitous moment, he realized that the circuit he built could be used as a chaotic oscillator.

Chaotic systems can be used for, among other things, random number generation, so making sure that they do not repeat in a reliable way is a valuable property of a circuit. [Tim]’s design uses LEDs in series with the base of each of three transistors, with the output of each transistor feeding into the input of the next transistor in line, forming a ring. At certain voltages close to the switching voltages of the transistors, the behavior of the circuit changes unpredictably both in magnitude and frequency.

Building real-life systems that exhibit true randomness or chaotic behavior are surprisingly rare, and even things which seem random are often not random enough for certain applications. [Tim]’s design benefits from being relatively simple and inexpensive for how chaotic it behaves, and if you want to see his detailed analysis of the circuit be sure to visit his project’s page.

If you want to get your chaos the old fashioned way, with a Chua circuit, look out for counterfeit multipliers.

DIY Plastic Speedboat For One

June 17, 2020 by 32 Comments

Coroplast (short for corrugated plastic) is an interesting material. It has a structure similar to cardboard, but since it’s plastic it’s waterproof and can be used for a unique set of applications. It’s typically used for political yard signs, but there are more fun things to do with this lightweight material than advertise. [Paul Elkins], for example, uses it to make speedboats.

The boats that [Paul] builds make use of a piece of coroplast which he cuts and folds into a basic hull shape. From there he begins to assemble the other things needed to finalize the boat, including strengthening the shape with wood, adding a steering wheel, building a transom to mount the motor to, and placing controls in the cockpit such as throttle and steering. The entire build is enough to propel a single person on a body of water at about five knots, which is impressive.

To make one of these yourself you’ll need a small outboard motor, but all of the other details of the build are outlined clearly in his series of videos. If you want to build your own boat but don’t like the idea of a noisy two-stroke motor right behind you, you can also look into building a boat with a silent mode of propulsion.

And if you’ve got a good supply of Coro, definitely check out [Paul]’s other projects, including a tiny house.

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Compile A Hydroponics System From Source

June 16, 2020 by 18 Comments

Tending to a garden is usually a rewarding endeavor, as long as there is good soil to work with. If there isn’t, it can either get frustrating quickly having to deal with soils like sand or hard clay, or it can get expensive by having to truck in compost each year. Alternatively, it’s possible to set up systems of growing plants that don’t need any soil at all, although this requires an automated system otherwise known as hydroponics to manage water and nutrients sent to the plants.

This setup by [Kyle] is unique in that it uses his own open-source software which he calls Mycodo to control the hydroponic system. It is loaded onto a Raspberry Pi 4 (which he notes can now be booted from a USB drive instead of an SD card) which controls all of the peripherals needed for making sure that the water has the correct amount of nutrients and chemical composition.

The build is much more than just a software control panel, though. [Kyle] walks through every part of setting up a small hydroponic system capable of effectively growing 15-20 plants indoors. He grows varieties of lettuce and basil, but this system can work for many more types of plants as well. With just slight variations, a similar system can not only grow plants like these, but fish as well.

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Disable Intel’s Backdoor On Modern Hardware

June 16, 2020 by 42 Comments

While the Intel Management Engine (and, to a similar extent, the AMD Platform Security Processor) continues to plague modern computer processors with security risks, some small progress continues to be made for users who value security of the hardware and software they own. The latest venture in disabling the ME is an ASRock motherboard for 8th and 9th generation Intel chips. (There is also a link to a related Reddit post about this project).

First, a brief refresher: The ME is completely removable on some computers built before 2008, and can be partially disabled or deactivated on some computers built before around 2013. This doesn’t allow for many options for those of us who want modern hardware, but thanks to a small “exploit” of sorts, some modern chipsets are capable of turning the ME off. This is due to the US Government’s requirement that the ME be disabled for computers in sensitive applications, so Intel allows a certain undocumented bit, called the HAP bit, to be set which disables the ME. Researchers have been able to locate and manipulate this bit on this specific motherboard to disable the ME.

While this doesn’t completely remove the firmware, it does halt all execution of code in a way that is acceptable for a large governmental organization, so if you require both security and modern hardware this is one of the few ways to achieve that goal. There are other very limited options as well, but if you want to completely remove the ME even on old hardware the process itself is not as straightforward as you might imagine.

Header image: Fritzchens Fritz from Berlin / CC0

Arduino Reduces Heating Costs

June 16, 2020 by 29 Comments

While almost everyone has a heater of some sort in their home, it’s fairly unlikely that the heat provided by a central heating system such as a furnace is distributed in an efficient way. There’s little reason to heat bedrooms during the day, or a kitchen during the night, but heating systems tend to heat whole living space regardless of the time of day or the amount of use. You can solve this problem, like most problems, with an Arduino.

[Karl]’s build uses a series of radiator valves to control when each room gets heat from a boiler. The valves, with a temperature monitor at each valve, are tied into a central Arduino Mega using alarm wiring. By knowing the time of day and the desired temperature in each room, the Arduino can control when heat is applied to each room and when it is shut off, presumably making the entire system much more efficient. It also has control over the circulating pump and some of the other boiler equipment.

Presumably this type of system could be adapted to a system which uses a furnace and an air handler as well, although it is not quite as straightforward to close vents off using a central unit like this as it is to work with a boiler like [Karl] has. With careful design, though, it could be done. Besides replacing thermostats, we can’t say we’ve ever seen this done before.

Thanks to [SMS] for the tip!

Tackling Trunked Radio With Software

June 16, 2020 by 12 Comments

For those starting to wade into radio as a hobby, one of the first real technical challenges is understanding trunked radio systems. On the surface, it seems straightforward: A control channel allows users to share a section of bandwidth rather than take up one complete channel, allowing for greater usage of the frequency range. In practice though it can be difficult to follow along, but now it’s slightly easier thanks to software defined radio.

This guide comes to us from [AndrewNohawk], who is located in San Francisco and is using his system to monitor police, fire, and EMS activity. These groups typically used trunked radio systems due to the large number of users. For listening in, nothing more than an RTL-SDR setup is needed, and the guide walks us through using this setup to find the control channels, the center frequency, and then identifying the “talk groups” for whichever organization you want to listen in on.

The guide goes into great detail, including lists of software needed to get a system like this started up, and since [AndrewNohawk] is a self-identified “radio noob” the guide is perfectly accessible to people who are new to radio and specifically new to trunked systems like these. Once you get the hang of it, it’s not too hard to scale up, either.

Rolling Out A New Robot Arm

June 12, 2020 by 2 Comments

A lot of great scientific breakthroughs come through imitating nature, but technology often runs up against limits in certain areas. This is particularly evident in robotics, where it takes a lot of effort (and cost) to build a robot which can effectively manipulate heavy objects but not crush others which are more delicate. For that, a research group has looked outside of nature, developing a robotic grasper which uses omnidirectional wheels to grab various objects.

The robot hand is composed of three articulating fingers with fingertips which are able to actively manipulate the object that the hand is holding. With static fingertips, it is difficult to manipulate an object in the hand itself, but with the active surfaces at the fingertips it becomes easier to rotate the object without setting it down first or dropping it.

The project is much more than designing the robot hand itself, too. The robot uses calculated kinematics to manipulate the objects as well, but a second mode was also tried where the robot was able to “learn” how to handle the object it was given. The video linked below shows both modes in operation, with interesting results. If you prefer more biologically-inspired robot arms, though, there are always novel designs based on non-humans.

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