Hipster Rotary Dial Adds Bluetooth 4.0

We have seen a few projects that convert a rotary dial for use with modern technology, but this one adds a new twist to the mix: it uses Bluetooth 4.0. [Silent] used a Nordic Semiconductor NRF51 DK development board for the project, which was built from the Nordic SDK source code for creating an HID (Human Interface Device). After what he claims was an hour or so of hacking, he was able to get this Arduino-compatible SoC dev board to detect the pulses from the rotary dial, then pass the appropriate number to a connected device as a key press. This means that his design should work with any device that has Bluetooth 4.0 support. It is powered from a big dry cell because, to quote [Silent], “small coin batteries are not hipster enough”.

It’s a simple project, and we have seen rotary cell phones before, but this still is ripe for expansion. You could either use a smaller, cheaper version of the Nordic chip at the center of this hack, as most of the dev board features aren’t used. Or you could do some more hacking, add support for the Bluetooth HSP headset profile, then wire it up to a vintage phone for the most hipster Bluetooth headset ever. We can’t wait until we see a hipster sitting in a coffee shop banging away on a typewriter and answering this. Get to it, people!

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Hello RAMPS, meet ESP8266

The proliferation of  DIY 3D printers has been helped in large measure by the awesome open-source RepRap project. A major part of this project is the RAMPS board – a single control board / shield to which all of the other parts of the printer can be easily hooked up. A USB connection to a computer is the usual link of choice, unless the RAMPS board has the SD-Card option to allow the 3D printer to operate untethered. [Chetan Patil] from CreatorBot built a breakout board to help attach either the ESP8266 WiFi or the HC-05 Bluetooth module to the Aux-1 header on the RAMPS board. This lets him stream G-code to the printer and allow remote control and monitoring.

While the cheap ESP8266 modules are the current flavor of the season with Hackers, getting them to work can be quite a hair tearing exercise. So [Chetan] did some hacking to figure out the tool chain for developing on the ESP module and found that LUA API from NodeMcu would be a good start. The breakout board is nothing more than a few headers for the ESP8266, the HC-05 and the Aux-1 connections, with a few resistors, a switch to set boot loader mode and a 3.3V regulator. If you’re new to the ESP8266, use this quick, handy, guide by [Peter Jennings] to get started with the NodeMCU and Lualoader. [Chetan]’s code for flashing on the ESP8266, along with the Eagle board design files are available via his Github repo. Just flash the code to the ESP8266 and you’re ready to go.

One gotcha to be aware of is to plug in the ESP module after the printer has booted up. Otherwise the initial communication from the ESP module causes the printer to lock up. We are sure this is something that can be taken care of with an improved breakout board design. Maybe use a digital signal from the Arduino Mega on the RAMPS board to keep the ESP module disabled for a while during start up, perhaps? The video after the break gives a short overview of the hack.

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Tricking a Car Stereo to Think Your Cellphone is a Tapedeck

When you have an older vehicle there’s not a lot of options in the stock stereo department, often a CD player and tape deck is what you get. When you want to play your tunes from your mobile what do you do? Buying an adapter, or a new head unit for that matter, isn’t any fun. So why not hack it? This isn’t just a mechanical marriage of a Bluetooth dongle and an elderly stereo. Some real work went into convincing the stereo that the BT receiver was the stock tape deck.

car-stereo-logic-analyzerAttacking the outdated Cassette deck [kolonelkadat] knew that inside the maze of gears and leavers, most of it is moving around actuating switches to let the radio know that there is a tape inside and that it can switch to that input and play. Tricking the radio into thinking there is a tape inserted is handled by an Arduino. Using a logic analyzer [kolonelkadat] figured out what logic signals the original unit put out and replicating that in his Arduino code.

Audio is handled by the guts of a bluetooth speaker with the output redirected into the radio where the signal coming off the tape head normally would have been directed. Join us after the break for a couple of videos with all of the details.

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Simple, Cheap Nitrate Tester is Open Source

Too much of a good thing can be a bad thing, and nitrate pollution due to agricultural fertilizer runoff is a major problem for both lakes and coastal waters. Assessing nitrate levels commercially is an expensive process that uses proprietary instruments and toxic reagents such as cadmium. But [Joshua Pearce] has recently developed an open-source photometer for nitrate field measurement that uses an enzyme from spinach and costs a mere $65USD to build.

The device itself is incredibly simple – a 3D printed enclosure houses an LED light source and a light sensor. The sample to be tested is mixed with a commercially available reagent kit based on the enzyme nitrate reductase, resulting in a characteristic color change proportional to the amount of nitrate present. The instrument reads the amount of light absorbed by the sample, and communicates the results to an Android device over a Bluetooth link.

Open-source instruments like this can really open up educational opportunities for STEM groups to get out into the real world and start making measurements that can make a difference. Not only can this enable citizen scientists and activists, but it also opens the door for getting farmers involved in controlling nitrate pollution at its source – knowing when a field has been fertilized enough can save a farmer unnecessary expense and reduce nitrate runoff.

There are a lot of other ways to put an open-source instrument like this to use in biohacking – photometery is a very common measuring modality in the life sciences, after all. We’ve seen similar instruments before, like a DIY spectrophotometer, or this 2015 Hackaday Prize entry medical tricorder with a built-in spectrophotometer. Still, for simplicity of build and potential impact, it’s hard to beat this instrument.

Fisher Price Bluetooth Speaker Hack

A good hacker hates to throw away electronics. We think [Matt Gruskin] must be a good hacker because where a regular guy would see a junky old 1980’s vintage Fisher Price cassette player, [Matt] saw a retro stylish Bluetooth speaker. His hack took equal parts of electronics and mechanics. It even required some custom 3D printing.

You might think converting a piece of old tech to Bluetooth would be a major technical challenge, but thanks to the availability of highly integrated modules, the electronics worked out to be fairly straightforward. [Matt] selected an off the shelf Bluetooth module and another ready-to-go audio amplifier board. He built a custom board to convert the stereo output to mono and hold the rotary encoder he used for the volume control. An Arduino (what else?) reads the encoder and also provides 3.3V to some of the other electronics.

The really interesting part of the hack is the mechanics. [Matt] managed to modify the existing mechanical buttons to drive the electronics using wire and hot glue. He also added a hidden power switch that doesn’t change the device’s vintage look. Speaking of mechanics, there’s also a custom 3D printed PCB holder allowing for the new board to fit in the original holder. This allows [Matt] to keep the volume control in its original location

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Hackaday Links: August 2, 2015

Over the last few years, Maker’s Asylum in Mumbai has grown from a garage to a very well stocked workspace with 140 members. They’re getting kicked out at the end of the month and they need some help. We just had a meetup at the Delhi branch of Maker’s Asylum, and these guys and gals are really cool.

Speaking of crowdfunding campaigns for hackerspaces, South Central Pennsylvania might be getting its own hackerspace. The 717 area code is a vast wasteland when it comes to anything anyone reading Hackaday would consider interesting, despite there being plenty of people who know their way around CNC machines, soldering irons, and welders. This needs to happen.

Need some help with Bluetooth standards? Tektronix has you covered with a gigantic poster of the physical layer. If only there were a repository of these handy, convenient reference posters.

Forgings and castings make for great YouTube videos, and this aluminum bell casting is no exception. There’s about 18 pounds of aluminum in there, which is pretty large as far as home casting goes.

Electronic Goldmine has an assortment of grab bags – spend a few dollars get a bag of chips, LEDs, diodes, or what have you. What’s in these grab bags? [alpha_ninja] found out. There’s some neat stuff in there, except for the ‘SMD Mixture’ bag.

Remember the found case molds for the Commodore 64C that became a Kickstarter? It’s happening again with the Amiga 1200. This is a new mold with a few interesting features that support the amazing amount of upgrades that have come out for this machine over the years. Being new molds, the price per piece is a little high, but that’s your lesson in manufacturing costs for the day.

Android-based Reflow Brings Solder Profiles to Your Lab

[Andy Brown] is a prolific hacker and ends up building a lot of hardware. About a year back, he built a reflow oven controller. The board he designed used a large number of surface mount parts. This made it seem like a chicken or egg first problem. So he designed a new, easy to build, Android based reflow controller. The new version uses just one, easy to solder surface mount part. By putting in a cheap bluetooth module on the controller, he was able to write an app which could control the oven using any bluetooth enabled Android phone or tablet.

The single PCB is divided into the high voltage, mains powered section separated from the low power control electronics with cutout slots to take care of creepage issues. A BTA312-600B triac is used to switch the oven (load) on and off. The triac is controlled by a MOC3020M optically isolated triac driver, which in turn is driven by a micro controller via a transistor. The beefy 12Amp T0220 package triac is expected to get hot when switching the 1300W load, and [Andy] works through the math to show how he arrived at the heat sink selection. To ensure safety, he uses an isolated, fully encased step down transformer to provide power to the low voltage, control section. One of his requirements was to detect the zero cross over of the mains waveform. Using this signal allows him to turn on the triac for specific angle which can be varied by the micro controller depending on how much current the load requires. The rectified, but unfiltered ac signal is fed to the base of a transistor, which switches every time its base-emitter voltage threshold is reached.

For temperature measurement, [Andy] was using a type-k thermocouple and a Maxim MAX31855 thermocouple to digital converter. This part caused him quite some grief due to a bad production batch, and he found that out via the eevblog forum – eventually sorted out by ordering a replacement. Bluetooth functions are handled by the popular, and cheap, HC-06 module, which allows easy, automatic pairing. He prototyped the code on an ATmega328P, and then transferred it to an ATmega8 after optimising and whittling it down to under 7.5kb using the gcc optimiser. In order to make the board stand-alone, he also added a header for a cheap, Nokia 5110 display and a rotary encoder selector with switch. This allows local control without requiring an Android device.

Gerbers (zip file) for the board are available from his blog, and the ATmega code and Android app from his Github repo. The BoM list on his blog makes it easy to order out all the parts. In the hour long video after the break, [Andy] walks you through solder tip selection, tips for soldering SMD parts, the whole assembly process for the board and a demo. He then wraps it up by connecting the board to his oven, and showing it in action. He still needs to polish his PID tuning and algorithm, so add in your tips in the comments below.

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