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Archive for the ‘28BYJ-48’ Category

It’s fair to say that building electronic gadgets is easier now than it ever has been in the past. With low-cost modular components, there’s often just a couple dozen lines of code and a few jumper wires standing between your idea and a functioning prototype. Driving stepper motors is a perfect example: you can grab a cheap controller board, hook it up to a microcontroller, and the rest is essentially just software. But recently [mechatronicsguy] wondered if even that was more hardware than was technically necessary to get the job done.

It’s not that he was intentionally looking to make things more complicated for himself, of course. His rationale was entirely economic; if you’re looking to drive a dozen or more stepper motors, even the “cheap” controllers can add up. So he started to wonder if he could skip the controller entirely and connect the stepper motor directly to the digital pins of an Arduino. Generally speaking this is a bad idea, but if you’re careful and are willing to take the risk, [mechatronicsguy] is living proof it’s possible

So what’s the trick to running a whopping seventeen individual stepper motors directly from the digital pins of an Arduino Mega? Well, to start with you’re not going to be running the beefy NEMA 17 motors like you might find in a 3D printer. [mechatronicsguy] is using the diminutive (and dirt cheap) 28BYJ-48, a light duty stepper used in many consumer products. Even with this relatively tiny motor, you need to crack open the case and cut a trace on the PCB to switch it from unipolar to bipolar.

Beyond that, you need to be careful. [mechatronicsguy] reports he’s had success running as many as ten of them at once, but realistically the fewer operating simultaneously the better. This is actually made easier due to the relatively poor specs of the 28BYJ-48 motor; its huge eleven degree step size means its not really susceptible to the same kind of slippage you’d get on a NEMA 17 when powered down. This means you can cut power to all but the actively moving motor and be fairly sure they’ll all stay where you left them.

With as popular as the 28BYJ-48 stepper is, there are several projects this “quick and dirty” method of interfacing could potentially work with. This small “barn door” star tracker is an obvious example, but we’ve also seen some very nice robotic arms built with these low-cost motors which could benefit from the technique.

Taking pictures in the 21st century is incredibly easy. So easy in fact that most people don’t even own a dedicated camera; from smartphones to door bells there are cameras built into nearly electronic device we own. So in this era of ubiquitous photography, you might think that a very slow and extremely low resolution camera wouldn’t be of interest. Under normal circumstances that’s probably true, but this single pixel camera built by [Tucker Shannon] is anything but normal.

At the heart of his unusual camera is the TCS34725 RGB color sensor from Adafruit which receives a tightly focused beam of incoming light by way of a 3D printed enclosure and a 3mm OD aluminum tube. This allows an Arduino Uno to determine the color of this tiny slice of light, making up a single pixel of the final color image. [Tucker] notes that you could even swap the color sensor out for a simple photocell if you don’t mind a black & white image at the end of the process.

In either event, once the light has been analyzed the sensor is repositioned autoturret-style by way of dual BYJ-48 stepper motors. This process continues on, spiraling outwards until the whole image is stitched together from these individual readings

Now compared to the camera in your phone, the resulting image might be a bit underwhelming. We’d say it’s a bit like looking at a digital picture on an 8 bit computer, but in truth even that might be overly generous. But even if it isn’t as crisp as modern eyes would like there’s no question that it’s certainly a recognizable image, which is all [Tucker] was shooting for.

Of course if your optical frugality is such that even this low-resolution camera is too sharp for your tastes, we’ve seen a similar concept  using a roof-mounted solar array.



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