Author Archives: John Baichtal

Testing Distance Sensors

via hardware – Hackaday

I’m working on a project involving the need to precisely move a tool based on the measured distance to an object. Okay, yeah, it’s a CNC mill. Anyway, I’d heard of time of fight sensors and decided to get one to test out, but also to be thorough I wanted to include other distance sensors as well: a Sharp digital distance sensor as well as a more sophisticated proximity/light sensor. I plugged them all into a breadboard and ran them through their paces, using a frame built from aluminum beams as a way of holding the target materials at a specific height.

Reflected-Light Sensors

I started with the Sharp GP2Y0D810Z0F digital distance sensor in a Pololu breakout board. It sports sample rate of 400 Hz, which seems more than adequate–I think my project wouldn’t need anything nearly that fast.

It’s basically a small-format replacement for light-based proximity senors, it works the same way, by shining a infrared light and looking for it to bounce back. The down side is that it doesn’t return a distance to the microcontroller–it’s binary, and triggers only when an object enters its field of view between 2 cm and 10 cm. If I were to have this sensor on my toolhead, it could tell if something was blocking the beam, but it couldn’t tell how close the tool was to the material.

Next I checked out the VCN4010 on a breakout board from Adafruit. Like the Sharp it’s more of a proximity sensor than a distance sensor. Adafruit’s testers found it worked best at around 10 mm to around 150 mm, or around 7.5″ and under. One advantage over the Sharp, the VCN4010 has a light sensor built into it. It has some nice features, like the product now supports I2C and interrupts, but I still found it to be not right for the application.

When you use the sensor it returns two numbers: ambient and proximity. The board’s chip has both a light sensor (the ambient number) and an infrared proximity sensor (the other number) and basically pings both sensors continuously and the data is viewable on the serial monitor.

Time of Flight

Forget infrared and parallax, the VL53L0X time-of-flight distance sensor uses an actual laser and measures how long it takes the light to bounce back. Adafruit put it on a board with a lev

el shifter and lux sensor, but you can find breakout boards from eBay or build your own.

It should provide accurate measurements up to 1200 mm (about 4 feet) which is clearly more than I need. On the other end, the VL52L0X isn’t rated to take measurements smaller than 50 mm, or two inches. I don’t think that’s a deal killer. If I have the sensor mounted on the toolhead and shining down, with a chuck and a bit in between, two inches might be alright. Adafruit has another breakout that only measures betw

een 5 mm and 200 mm. To be honest, I’ll never have the sensor in a position where it would need four feet of space to work.

Both time-of-flight sensors have a very tight cone of measurement. Forget an ultrasonic’s tendency to spray sound everywhere, bouncing off of the wrong things and theoretically polluting other ultrasonics. The ToF shoots a little laser beam out and it’s very directional; it senses what is in front of it and nothing else.

On the downside, you also need to point the laser at something that will reflect it properly. I tested out the ToF with a variety of materials, and it definitely likes white and gray. For my project I might need to ensure there’s a swatch of something reflective but not too reflective, at which to aim the laser. Ambient lighting and a reflective white surface improves the accuracy to around +/-3%, while less ideal environments lowerthis to worse than 10%. For my project, with precision important, 10% could mean the difference between the tool touch the material and it missing completely.

Another downside, and this one is minor, is that you can only connect one sensor to your I2C bus because they have a single hard-coded I2C address. There are hacks to work around this, and there’s even a dedicated I2C address-translation chip that’ll get you out of this particular jam. The good news is that I wasn’t planning to use more than one sensor anyway.

I had a lot of fun testing out the sensors and getting a feel for what their capabilities. And while I am intrigued by the proximity sensing properties of the Sharp and VCN4010, I feel like my application needs more precision. I need to know precisely how far to lower the toolhead, and the ToF’s precision seems perfect for my purposes.

Filed under: hardware

Using a Decade Counter to Make LEDs Flash

via hardware – Hackaday

[Andrea De Napoli] created a LED display consisting of a half-dozen LEDs connected to the inverted signals of a CD4017 decade counter, giving the effect that a dark LED is running back and forth. The CD4017 works by activating 10 outputs, one at a time, as controlled by a clock signal sent to pin 14.

The first and last LEDs are lit by outputs 0 and 5 with the help of a PNP transistor and a 12K resistor. The middle four LEDs are switched by two outputs each and go dark when one of them goes high. [Andrea] really delves into the CD4017 and he shares a lot of detail in the project page.

Hackaday publishes a lot of posts about obscure ICs: Project 54/74 aims to create a database of die images of 5400 and 7400 series ICs. In a remix of a classic, the Baby 10 uses a 4017 to make a music sequencer.

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Bearing-in-Bearing Fidget Spinner Taken to the Max

via hardware – Hackaday

People who know about bearings go through a phase of bemusement with regards to fidget spinners. We say something like, “man, I got a whole box of bearings in the basement.” Then we go through a “OK, I’ll make one” phase and print one out of PLA.

[fishpepper] took that sentiment a step further. After being forced to print spinners for his kids, he got jealous and decided to make his own—but his spinner would be a version for engineers. [fishpepper]’s ginormous spinner consists of five bearings superglued inside each other, with the grease cleaned out of the insides to make them spin faster. The inner two sets are doubled up bearings, 6 mm x 17 mm x 6 mm and 17 mm x 30 mm x 7 mm. The middle bearing measures 30 mm x 55 mm x 13 mm, and the fourth bearing 55 mm x 90 mm x 18 mm.

If you want to stop here, it’s a good size, around two inches across. However, [fishpepper] took it a step further, adding a fifth bearing, a 90 mm x 140 mm x 24 mm monster weighing in at 1 kg by itself. The total weight comes to 1.588 kg with the 3D-printed hub included. If you want to make one yourself, check out [fishpepper’s] bearing-in-bearing spinner tutorial which guides you through the various steps.

Hackaday likes fidget spinners so much you’d think we were in 6th grade: we’ve published posts on the three-magnet spinner hack, a fidget-spinning robot, and teaching STEAM with fidget spinners.


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Use All that Extra Space with PCB Panelization

via hardware – Hackaday

Anyone who’s made a PCB has encountered the conundrum of having to pay for space that you don’t use… for instance, designing a round PCB and seeing the corners go to waste. The solution? Smaller boards added to the blank spots.

One logical stumbling block might be that you simply don’t have a small PCB design ready to go. Latvian hacker [Arsenijs] created a resource of small PCBs that can be dropped into those blank spots, as well as a tutorial on how to combine the gerbers into a single panel.

Great minds think alike, and this guide is following hot on the heels of [Brian Benchoff’s] article on panelization. They’re both a great read. It’s interesting to think that not long ago we would see multiple guides on home etching boards and now we’ve climbed the production ladder to guides that help better utilize PCB fab houses. Neat!

This project seems a logical spinoff of [Arsenijs]’s ZeroPhone Pi smartphone project, a finalist for the 2017 Hackaday Prize that makes a low-cost phone using a stack of PCBs. One imagines that while prototyping the phone [Arsenijs] ended up with a lot of wasted space! Fill that up with smaller designs like breakouts, or decorative items like a hackerspace business card. If you’re looking for small PCBs you can find a few in the files area of the project on Otherwise, you can share yours and [Arsenijs] will add them.

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Dirty Now Does Cables

via hardware – Hackaday

PCB makers Dirty made a name for themselves in the prototype PCB biz, with a convenient web form and numerous options for PCB color, thickness, layers, silk screening, and so on. Now they’ve branched out into custom cabling with Dirty Cables.

You can design it yourself by dragging wires and connectors out of a sidebar and arranging them on a workspace, deciding which wire goes to what pin of the connector. Your choices for wires include various gauges and ribbon configurations. You choose a color (they have eleven) select connectors and drag those out too–choose from 17 cable-to-cable and cable-to-board connector families. We made a quick cable with four 32ga wires and two 16ga wires, with two different connectors on each side, with pricing updated realtime. If you want a sample pack of connectors, Dirty sells them for $10.

The downside to the service: there’s a minimum order of 100, though paying Shenzhen prices might make it worth your while. Just imagining crimping all of those connectors makes Hackaday’s hands hurt.

To get a sense of the diversity of connectors out there, read Elliot’s piece on the connector zoo that we published last year.

[thanks, Akiba]

Filed under: hardware