Author: Al Williams

4504 Articles

Tracked Robot Makes Sand Drawings

June 24, 2020 by 6 Comments

[Ivan] seems to enjoy making 3D printed vehicles with tracks. His latest one uses 50 servo motors to draw patterns in the sand at the beach. You can see it work in the video below. Well, more accurately you can see it not work and then work as the first iteration didn’t go exactly as planned.

An Arduino Mega 2560 provides the brains and the whole unit weighs in at almost 31 pounds, including the batteries. We didn’t see Ivan’s design files, although it wouldn’t be hard to do your own take on the robot.

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Raspberry Pi Takes Control Of Ham Radio

June 24, 2020 by 16 Comments

Today’s ham radio gear often has a facility for remote control, but they most often talk to a computer, not the operator. Hambone, on the other hand, acts like a ham radio robot, decoding TouchTone digits and taking action — for example, keying the radio and reading off the weather — in response to the commands received.

The code is in Python and uses numpy’s fast Fourier transform to identify digits. We’d be interested to test the performance of that compared to doing a Goertzel to specifically probe for the 8 digit tones: there are four row tones and four column tones. On the other hand, the FFT is handy and clearly works fast enough for this application.

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Eico Signal Generator Gets A Repair

June 23, 2020 by 5 Comments

The Eico model 377 was a pretty common audio signal generator. [The Radio Mechanic] picked one up from 1956 that was in reasonably good shape, and shares a teardown and repair of the unit that you can see in the video below. The device could produce sine and square waves using a few tubes.

The unit was a bit different inside than expected because there were several versions made that shared the same model number. The bottom of the case had some goo in it, which is never a good sign. Unsurprisingly, the culprit was an old capacitor.

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OTA ESP32 GUI Makes Updates Simple

June 23, 2020 by 18 Comments

One of the disadvantages of having cheap WiFi-capable boards like those based on the ESP32 is that you have to update them. If you have even a few in every room of your house, it can be a pain to pull them out and connect them to a cable for programming. Over the air programming is a great answer, and [Kevin] shows how you can control the update via a simple GUI. You can see a video demonstration of how it works below.

[Kevin] uses a ready-made OTA library to do the work, but creates a GUI configuration and downloader tool. There is a manual step to force the board into the OTA mode, which might be a mild inconvenience, but it improves security since you need physical access to the device to do an update.

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Educational Radio, Educates

June 22, 2020 by 11 Comments

Analyzing and troubleshooting a modern AM/FM radio, digital radio, or TV can be a pretty daunting task. However, a common AM radio is easy to understand, experiment with, and repair. Learning about that will help you understand more complex circuits later. That’s the idea behind the Elenco AM radio which is built on a wide-open PCB with markings for all the important sections. [The Offset Volt] uses one of these to explain how a receiver works, especially how a diode detects the signal and how the automatic gain control works.

Between a series of diagrams and live scope demonstrations, you can see the effects of capacitance in the receiver along with other circuit effects.

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Decapsulating A Dual Triode

June 21, 2020 by 8 Comments

We see quite a bit of work where people decapsulate ICs or other solid state devices to expose their inner workings. But how about hollow state? [Tomtektest] had a dual triode that has lost its vacuum integrity — gone to air, as he calls it — and decided to open it up to better expose its inner workings. (Video, embedded below.)

Of course, you can always see the innards through the glass, but it is interesting to have the envelope out of the way. Apparently, how you remove the glass is a bit tricky if you don’t want to damage the working bits as you remove it.

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Simulate Your World With Hash.ai

June 21, 2020 by 8 Comments

We will admit that we often throw together software simulations of real-world things, but we’ll also admit they are usually quick and dirty and just dump out text that we might graph in a spreadsheet or using GNUPlot. But with Hash.ai, you can quickly generate simulations of just about anything quickly and easily. The simulations will have beautiful visualizations and graphs, too. The tool works with JavaScript or Python and you don’t have to waste your time writing the parts that don’t change.

The web-based tool works on the idea of agents. Each agent has one or more behaviors that run each time step. In the example simulation, which models wildfires in forests, the agent is named forest, although it really models one virtual tree. There’s also a behavior called forest which controls the tree’s rate of growth and chance of burning based on nearby trees and lightning. Other behaviors simulate a burning tree and what happens to a tree after burning — an ember — which may or may not grow back.

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