A Peek Into A Weed-Eating Robot’s Test Fixtures

July 7, 2018 by Donald Papp 2 Comments

When it comes to production, fast is good! But right the first time is better. Anything that helps prevent rework down the line is worth investing in. Some of the best tools to catch problems are good test fixtures. The folks at Tertill (a solar-powered robot for killing weeds that kickstarted last year) took the time to share two brief videos of DIY test fixtures they use to test components before assembly.

The videos are short, but they demonstrate all the things that make a good test: on the motor tester there are no connectors or wires to fiddle with, the test starts automatically, and there is clear feedback via prominent LEDs. The UI board tester also starts automatically and has unambiguous LED feedback, and sports a custom board holder with a recess just the right shape for the PCB. Once the board is in, the sled is pushed like a drawer to make contact with the test hardware and begin the test. The perfectly formed recesses in both units serve another function as well; they act as a go/no-go test for the physical shape of the components and contacts being tested.

Both videos are embedded below; and while there isn’t much detail on the actual test hardware, we do spy a Raspberry Pi and at least two Adafruit logos among other hacker-familiar elements like laser-cut acrylic, 3D printed plastic, pogo pins, and a PVC junction box.

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DIY Socket For Prosthetics Contains Power Supply, Charger

July 6, 2018 by Donald Papp 5 Comments

Innovation in prosthetics is open to anyone looking to enhance the quality of life, but there’s an aspect of it that is sometimes under-served. The DIY Prosthetic Socket entry to the Hackaday Prize is all about the foundation of a useful prosthesis: a custom, form-fitting, and effective socket with a useful interface for attaching other hardware. While [atharvshringaregt] is also involved with a project for a high-tech robotic hand with meaningful feedback, socket fitting and design is important enough to be its own project.

The goal is not just to explore creating these essential parts in a way that’s accessible and affordable to all, but to have them include a self-contained rechargeable power supply that can power attachments. Thoughtful strap placement and a power supply design that uses readily available components with a 3D printed battery housing makes this DIY prosthetic socket a useful piece of design that keeps in mind the importance of comfort and fitting when it comes to prosthetics; even the fanciest robot hand isn’t much good otherwise.

Raspberry Pi Zero Stepper Driver, First Of Many Modules

July 1, 2018 by Donald Papp 32 Comments

The Raspberry Pi in general (and the Zero W model in particular) are wonderful pieces of hardware, but they’re not entirely plug-and-play when it comes to embedded applications. The user is on the hook for things like providing a regulated power source, an OS, and being mindful of proper shutdown and ESD precautions. Still, the capabilities make it worth considering and [Alpha le ciel] has a project to make implementation easier with the Raspberry Pi Zero W Stepper Motor Module, which is itself part of a larger project plan to make the Pi Zero W into a robust building block for robotic and CNC applications.

[Alpha le ciel] is building this stepper motor module as the first of many Raspberry Pi hats meant to provide the Raspi with the hardware for robotics applications. This module, in particular, features two A4988 stepper motor drivers, a connector for a power supply or battery providing 7-20V, and a buck converter to bring that power down to the 5V needed by the Pi itself. All the relevant pins are broken out onto the Pi’s GPIO header, making this module the simplest way possible to add a pair of motors to a Pi. What does that mean? Printers or self-balancing robots, really whatever you want.

A stepper driver that conforms to the footprint of the Pi Zero is a good start, and the larger concept of creating additional modules is a worthy entry to the Hackaday Prize.

PCB Holder Quick-fix Turns Out To Be Big Improvement

July 1, 2018 by Donald Papp 15 Comments

When something needs improving, most hacks often make a small tweak to address a problem without changing how things really work. Other hacks go a level deeper, and that’s what [Felix Rusu] did with his 3D printed magnetic holders. Originally designed to address a shortcoming with the PCB holders in his LE40V desktop pick-and-place machine, they turned out to be useful for other applications as well, and easily modified to use whatever size magnets happen to be handy.

The problem [Felix] had with the PCB holders on his pick-and-place was that they hold the board suspended in midair by gripping the sides. The board is held securely, but the high density of parts on panelized PCB designs leads to vibrations in the suspended board as the pick-and-place head goes to work. Things are even worse when the board is v-scored for the purpose of easily snapping apart the smaller boards later; they sometimes break along the score lines due to the stress.

Most people would solve this problem by putting a spacer underneath the board to stabilize things, but [Felix] decided to go a level deeper and change the mounting system altogether with a simple mod. The boards now lie on a flat metal plate, and his magnetic holders are simple to make and easily do the job of holding any size PCB secure. As a bonus, it turns out that the holders also do a passable job of holding work materials down on a laser cutter’s honeycomb table. A video overview is embedded below, and the design files are available on Thingiverse.

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XLIDAR Is A Merry-Go-Round Of Time-Of-Flight Sensors

June 29, 2018 by Donald Papp 38 Comments

[JRodrigo]’s xLIDAR project is one of those ideas that seemed so attractively workable that it went directly to a PCB prototype without doing much stopping along the way. The concept was to mount a trio of outward-facing VL53L0X distance sensors to a small PCB disk, and then turn that disk with a motor and belt while taking readings. As the sensors turn, their distance readings can be used to paint a picture of the immediate surroundings (at least within about 1 meter, which is the maximum range of the VL53L0X.)

The hardware is made to be accessible and has a strong element of “what you see is what you get.” The distance sensors are on small breakout boards, and the board turns the sensor disk via a DC motor and 3D printed belt drive. Even the method of encoding the disk’s movement and zero position has the same WYSIWYG straightforwardness: a spring contact and an interrupted bare copper trace on the bottom of the sensor disk acts as a physical switch. In fact, exposed copper traces in concentric circular patterns and spring pins taken from an SD card socket are what provide power and communications as the disk turns.

The prototype looks good and sounds like it should work, but how well does it hold up? We’ll find out once [JRodrigo] does some testing. Until then, the board designs are available on the project’s GitHub repository if anyone wants to take a shot at their own approach without starting from scratch.

Marvel At Soviet-era Smart Display’s Tiny Size

June 9, 2018 by Donald Papp 14 Comments

The Soviet-era 490IP1 LED. The digit is a mere 2.5 mm in height. Pictured with the Texas Instruments TIL306. [image: industrialalchemy.org]

It’s easy to assume that older components will be less integrated and bulkier than we might otherwise expect. Then something seems ahead of its time, like the teeny-tiny 490IP1 LED which was produced in the former Soviet Union. [AnubisTTP] obtained and shared images of this tiny integrated single digit LED display in which the number measures a scant 2.5 mm tall; in production it was made easier to read with an external bubble lens magnifier clipped to the outside. The red brick the 490IP1 is pictured with is the Texas Instruments TIL306, a relatively normal sized DIP component with similar functionality.

The 490IP1 is called an intelligent LED display because the package contains a decade counter and driver circuitry for the integrated seven-segment LED digit, complete with a carry signal that meant multiple displays could be chained together. It is notable not just due to its size, but because the glass cover makes it easy to see the die inside, as well as the wire-bonded pads.

It’s always fascinating to see glimpses of the development path that display technologies took. It’s easy to take a lot of it for granted today, but back before technology was where it is now, all sorts of things were tried. Examples we’ve seen in the past include the fantastic (and enormous) Eidophor projector which worked by drawing images onto a rotating disk of oil with an electron gun. On the smaller end of things, the Sphericular display used optics and image masks to wring a compact 0-9 numerical display out of only a few lamps at the back of a box.

Servo Becomes Mini Linear Actuator

June 2, 2018 by Donald Papp 11 Comments

RC servos are a common component in many robotics projects, but [Giovanni Leal] needed linear motion instead of the rotary actuation that servos normally offer. The 3D Printed Mini Linear Actuator was developed as a way to turn a mini servo into a linear actuator, giving it more power in the process.

A servo uses a potentiometer attached to the output shaft in order to sense position, and the internal electronics take care of driving the motor to move the shaft to the desired angle. [Giovanni] took apart an economical mini servo and after replacing the motor with a 100:1 gear motor and using it to power a compact 3D printed linear actuator, he used the servo’s potentiometer to read the linear actuator’s position. As a result, the linear actuator can exert considerably more force than the original servo while retaining exactly the same servo interface. You can see one being assembled and tested in the video embedded below, which is part of [Giovanni]’s entry for The 2018 Hackaday Prize.

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