3D Printers Get A Fuel Gauge: Adding A Filament Scale To OctoPrint

August 10, 2018 by Tom Nardi 17 Comments

It seems a simple enough concept: as a 3D printer consumes filament, the spool becomes lighter. If you weighed an empty spool, and subtracted that from the weight of the in-use spool, you’d know how much filament you had left. Despite being an easy way to get a “fuel gauge” on a desktop 3D printer, it isn’t something we often see on DIY machines, much less consumer hardware. But with this slick hack from [Victor Noordhoek] as inspiration, it might become a bit more common.

He’s designed a simple filament holder which mounts on top of an HX711 load cell, which is in turn connected to the Raspberry Pi running OctoPrint over SPI. If you’re running OctoPrint on something like an old PC, you’ll need to use an intermediate device such as an Arduino to get it connected; though honestly you should probably just be using a Pi.

On the software side, [Victor] has written an OctoPrint plugin that adds a readout of current filament weight to the main display. He’s put a fair amount of polish into the plugin, going through the effort to add in a calibration routine and a field where you can enter in the weight of your empty spool so it can be automatically deducted from the HX711’s reading.

Hopefully a future version of the plugin will allow the user to enter in the density of their particular filament so it can calculate an estimate of the remaining length. The next logical step would be adding a check that will show the user a warning if they try to start a print that requires more filament than the sensor detects is currently loaded.

This is yet another excellent example of the incredible flexibility and customization offered by OctoPrint. If you’re looking for more reasons to make the switch, check out our guide on using OctoPrint to create impressive time lapse videos of your prints, or how you can control the printer from your mobile device.

DIY Scientific Calculator Powered By Pi Zero

August 7, 2018 by Tom Nardi 25 Comments

It’s the eternal question hackers face: do you built it, or do you buy it? The low cost and high availability of electronic gadgets means we increasingly take the latter option. Especially since it often ends up that building your own version will cost more than just buying a commercial product; and that’s before you factor in the time you’ll spend working on it.

But such concerns clearly don’t phase [Andrea Cavalli]. Sure he could just buy a scientific calculator, but it wouldn’t really be his scientific calculator. Instead, he’s taking the scenic route and building his own scientific calculator from scratch. The case is 3D printed, the PCB is custom, and even the software is his own creation.

His PCB hooks right up to the GPIO pins of the internal Raspberry Pi Zero, making interfacing with the dome switch keyboard very easy. The board also holds the power management hardware for the device, including the physical power switch, USB connection for charging, and TPS79942DDCR linear regulator.

The case, including the buttons, is entirely 3D printed. At this point the buttons don’t actually have any labels on them, which presumably makes the calculator more than a little challenging to use, but no doubt [Andrea] is working on that for a later revision of the hardware. A particularly nice detail is the hatch to access the Pi’s micro SD card, making it easy to update the software or completely switch operating systems without having to take the calculator apart.

After the kernel messages scroll by, the Pi boots right into the Java calculator environment. This gives the user a fairly standard scientific calculator experience, complete with nice touches like variable highlighting. The Mario mini-game probably isn’t strictly required, but if you’re writing the code for your own calculator you can do whatever you want.

Here at Hackaday we’ve seen a calculator that got a Raspberry Pi upgrade, a classic scientific calculator emulated with an Arduino, and of course we’ve raved about the NumWorks open source graphing calculator. Even with such stiff competition, we think this project is well on its way to being one of the most impressive calculators we’ve ever come across.

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Raspberry Pi On The Go Powers Car System

August 1, 2018 by Al Williams 9 Comments

Most new cars have GPS, rear cameras, and all the other wonders an on-board system can bring. But what if you have an old car? [Fabrice Aneche] has a 2011 vehicle, and wanted a rearview camera. He started with a touch screen, a Raspberry Pi 3, and a camera. But you know how these projects take on a life of their own. So far, the project has two entries in his blog.

It wasn’t long before he couldn’t resist the urge to add a GPS. But that’s no fun without maps. Plus you need turn-by-turn directions. [Fabrice] did a lot of the user interface using Qt5 and QML. He started out running it with X11 but that was slow. It turns out though that Qt5 can drive the Pi’s video directly without using X11, so that’s what he wound up doing. The code that isn’t in QML — mainly dealing with the GPS location — is written in Go, while the code for MOCS (My Own Car System) is on GitHub.

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Need A Tiny CRT? Karaoke Might Just Help

July 31, 2018 by Lewin Day 30 Comments

[Brett] is working on a video installation, and for the past few months, has been trying to get his hands on tiny CRTs any way he can. After initially coming up short, he happened across a karaoke machine from 2005, and got down to work.

Karaoke machines of this vintage are typically fairly low-rent affairs, built cheaply on simple PCBs. [Brett] found that the unit in question was easy to disassemble, having various modules on separate PCBs joined together with ribbon cables and headers. However, such machines rarely have video inputs, as they’re really only designed to display low-res graphics from CD-G format discs.

While investigating the machine, initial research online proved fruitless. In the end, a close look at the board revealed just what [Brett] was looking for – a pin labeled video in! After throwing in a Raspberry Pi Zero and soldering up the composite output to the karaoke machine’s input pin, the screen sprung to life first time! This initial success was followed by installing a Raspberry Pi 3 for more grunt, combined with a Screenly install – and a TRS adapter the likes of which we’ve never seen before. This allows video to be easily pushed to the device remotely over WiFi. [Brett] promises us there is more to come.

Karaoke is a sparse topic in the Hackaday archives, but we’ve seen a couple builds, like this vocal processor. If you’ve got the hacks, though? You know where to send ’em.

GTA: San Andreas Radio Earns Six-Star Wanted Level

July 25, 2018 by Kristina Panos 14 Comments

[Raphaël Yancey] wanted to be able to jam to Bounce FM and Radio:X all the time, without having to steal a car or a street sweeper in San Andreas. As people who like to put on the sad piano building music from The Sims and write Hackaday posts, we can totally relate.

But this isn’t just another one of those jam-a-Pi-into-a-vintage-radio-and-call-it-a-sandwich projects (not that there’s anything wrong with those). This thing acts like a real radio. All the stations play continuously whether you’re tuned in or not, and they bleed into each other as you go up and down the dial.

After much trial and error, [Raphaël] found a Python mixer that would work, but it was no longer maintained. He forked it, squashed a bug or two, and wrote a module for KY040 rotary encoders to make them play nice with the Pi. The snake charming doesn’t stop there: the rock star of this project is [Raphaël]’s virtual radio software, which handles the audio blending as he tunes between stations. A step-by-step tutorial is coming soon, so watch [Raphaël]’s site for updates. Tune past the break to give it a listen.

Adventures in Raspi radio-ing don’t have to be one-way. Here’s how you can turn one into an AM/FM+ transmitter using a DVB-T dongle and SDR.

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Behind The Pin: How The Raspberry Pi Gets Its Audio

July 13, 2018 by Jenny List 54 Comments

Single board computers have provided us with a revolution in the way we approach computing as hardware creators. We have grown accustomed to a world in which an entire microcomputer has become a component in its own right rather than a complex system, and we interface to them as amorphous entities through their exposed interfaces. But every pin or socket on a single board computer has something behind it, so following up on a recent news-inspired item in which we took a look at what lies behind the Ethernet jack on a Raspberry Pi, we’d like to continue that theme by looking behind more pins and interfaces. So today we’ll stay with the Raspberry Pi, and start with an easy target by taking a look down its audio jack.

All the main Raspberry Pi board releases since 2012 with the exception of the Pi Zero series, have featured a 3.5mm jack carrying line-level audio. The circuits are readily accessible via the Raspberry Pi website, and are easy enough to understand because of course all the really hard work is done within the silicon of the Broadcom system-on-chip. Looking at the audio circuitry, we’ll start by going back to the original Pi Model B from 2012 (PDF) because though more recent models have seen a few changes, this holds the essence of the circuitry.

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Old Time Traffic Signal Revived With A Raspberry Pi Controller

July 12, 2018 by Dan Maloney 28 Comments

Anyone with even a passing familiarity with the classic animated shorts of the 1940s will recognize the traffic signal in the image above. Yes, such things actually existed in the real world, not just in the Looney world of [Bugs Bunny] et al. As sturdy as such devices were, they don’t last forever, though, which is why a restoration of this classic Acme traffic signal was necessary for a California museum. Yes, that Acme.

When you see a traffic signal from the early days of the automotive age like this one, it becomes quickly apparent how good the modern equivalent has become. Back in the day, with a mix of lights distributed all over the body of the signal, arms that extend out, and bells that ring when the state changes, it’s easy to see how things could get out of hand at an intersection. That complexity made the restoration project by [am1034481] and colleagues at the Southern California Traffic Museum all the more difficult. Each signal has three lights, a motor for the flag, and an annunciator bell, each requiring a relay. What’s more, the motor needs to run in both directions, so a reversing relay is needed, and the arm has a mechanism to keep it in position when motor power is removed, which needs yet another relay. With two signals, everything was doubled, so the new controller used a 16-channel relay board and a Raspberry Pi to run through various demos. To keep induced currents from wreaking havoc, zero-crossing solid state relays were used on the big AC motors and coils in the signal. It looks like a lot of work, but the end results are worth it.

Looking for more information on traffic signal controls? We talked about that a while back.