Simple, Cheap Nitrate Tester Is Open Source

August 11, 2015 by Dan Maloney 19 Comments

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

August 7, 2015 by Al Williams 14 Comments

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

August 2, 2015 by Brian Benchoff 8 Comments

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

July 15, 2015 by Anool Mahidharia 13 Comments

[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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Coin-Op Weather

July 8, 2015 by Dan Maloney 1 Comment

When you have access to your own CNC machine, you tend to make stuff first and ask questions later. That sounds like how [Rui Cabral] came up with a weather station stuffed into a miniature arcade game cabinet.

Standing only about 16 cm tall, the cabinet is quite detailed and resembles the familiar arcade form factor that has consumed countless quarters. It even appears to be made of particle board like the big boys. The screen cutout is filled by a 84×48 monochrome Nokia display, and the rest of the cabinet’s interior is stuffed with a CNC-milled PCB, temperature and humidity sensors, an RTC, and a Bluetooth module for uploading data to a phone. [Rui] even manages to work in an homage to the grand-daddy of all arcade games with a Pong splash screen.

Another good-looking display for this project might have been this ePaper badge made into a weather station. And we’ve featured even tinier arcade cabinets too, though perhaps not as functional.

[Rui] takes us on a video tour of his build after the break.

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New Part Day: Nordic’s New Bluetooth SoC

June 21, 2015 by Brian Benchoff 29 Comments

You don’t need to look very hard to find Nordic’s nRF51 wireless module; it’s found in hundreds of products and dozens of projects over on hackaday.io. The nRF51 is a SoC that includes an ARM Cortex M0 processor and a variety of radios for Bluetooth and other protocols. Useful, if a bit limited in processing power.

Now, Nordic has a new SoC. It’s the nRF52, a Cortex M4F processor, a Bluetooth radio, NFC, and a bunch of Flash and RAM to make just about anything you can think of possible. Yes, it’s an upgrade to the nRF51 – a better processor and NFC, and all the possibilities that come with that. Currently there’s only one part and two package options: a 6x6mm QFN48, or a wafer chip that will be covered with impregnable goo.

Already there are SDKs for IAR Workbench, Keil4 and 5, and gcc. The SDKs won’t help you quite yet; it’s not available through the usual distributors yet, but the nRF52 Preview develoment kit is. That’s a single board development kit for the nRF52, with Arduino pinouts and Mbed support.

Thanks [Alvin] for sending this in from Trondheim.

IR Remote For Smartphone Via Bluetooth Adapter

June 19, 2015 by Anool Mahidharia 8 Comments

Quite often, the raison d’être for building a project is to learn and hone one’s skills. In which case it doesn’t matter if the end use seems a bit frivolous. [indiantinker] built BlueIR, a device to control Bluetooth A2DP devices using an archaic IR Remote using a BT-Aux Adapter.

Sounds convoluted? Let’s try again. He uses an old IR remote to send data to a MSP430-series microcontroller, which is connected over serial to a USB Bluetooth Receiver Adapter, which in turn is connected to a set of wired speakers. The Bluetooth adapter is paired with his phone. The IR remote allows him to control the audio player commands on his phone from a far greater distance compared to the bluetooth adapter.

He begins by breaking open the BT adapter to find that the markings on the chip have been erased. What he did find instead, were two pads promisingly marked as TX and RX, but he still did not know the baud rate or the command set. Digging around the Internet, he figured out that the chip used was the OVC3860 Bluetooth 2.0 + EDR Stereo Audio Processor and found its list of AT Commands. After some tests using a serial console he figured out that it worked at 115600 baud. Soon enough, he had it hooked up to the MSP430 Launchpad and was able to communicate. Next up, he built a small PCB, using the toner transfer method. The board consists of the MSP430G2553 micro controller, IR receiver, LED, some decoupling capacitors and a few pull up resistors. He leached power from the 3.3V regulator on the host BT adapter. The assembled PCB is piggy backed on top of the BT adapter for the time being, and a 3d printed housing is on his to-do list. His code is available at the BlueIR Github repo and the video below shows it in action.

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