November 17, 2018

PurpleAir Sensor Investigation and Teardown, Pt1


With the ongoing poor air quality all over Central California due to the Camp Fire, the interest of providing fine grained and reliable air pollution measurements peaked. One of the interesting providers of data is the website PurpleAir.com. The data for PurpleAir is sourced from a series of sensors sold through the website

February 20, 2018

Parts Roundup: FemtoFET


Ever felt like your board level MOSFETs were too large? Texas Instruments now has an answer! Measuring in it as small as 0.7mm x 0.6mm, these FETs are small for board, but most importantly retain a sane PCB layout: the gate is actually at one end! No more squishing a layout where the gate has to trapeze through either of the high current paths, now you can more easily use two layer boards where all of the control signals to the FET are kept on the logical end of the device and nearer the MCU or other controller. Read more

March 31, 2017

Simple CO2 Solenoid Carbon Doser Project


Controlling pressurized carbon dioxide (CO2) delivery into a Calcium reactor or into a planted tank with precision can be fraught with problems. The conventional mechanism is to use a needle valve after a pressure regulator - this design is very finicky to adjust for low flow rates and has a tendency to drift over time, meaning your carefully controlled delivery is now out of whack. In addition, if you use a pH controller driving an AC solenoid valve, the valve actuation can be quite audible. Read more

November 14, 2016

EVE-Central.com in the age of EVE Ascension


After a week delay while the United States elected an authoritarian misogynist xenophobe (more on that in another post), CCP games will be releasing one of the most fundamental player-focused changes in EVE Online; free-to-play in the form of Alpha Clones. This is a critical inflection point in the history of the game I first picked up in 2003, as an alternative to Earth and Beyond MMO which was on its downward spiral. Read more

May 10, 2016

Spectrometer Pt 2 - Driving


First things first, we need to figure out how to drive and read the spectrometer. There are two key diagrams to consult - the suggested application and the timing diagram. The application diagram shows several key signals, some of which the meaning isn’t clear at first. After reading through the rest of datasheet, you can generally make out the following pins: Video - the spectrometer is like a 2d camera - it is an image sensor in a line after all. Read more

May 9, 2016

Spectrometer for LED lighting analysis


Hi! You may remember me from other threads like LEDBrick DIY puck and high density stars, plus drivers (now available on blueAcro.com and the Apogee sensor PAR interface board. Many moons (months) ago, I dropped some money into a GroupGets buy for a pair of Hamamatsu Micro-spectrometers. They can resolve light intensity between 340-780nm in up to 15nm increments. They are not cheap ($180 on groupgets, qty1), but are a lot cheaper than other commercial pre-packaged light spectrum units that employ an actual spectrometer (and not a coarse approximation using an RGB light sensor). Read more

July 13, 2015

Design Log: LEDBrick - part 2


Nearly 6 months later, and after back-burnering the project multiple times, I’ve made some significant progress on the LEDBrick aquarium light. In the space between blog posts, I’ve: Received a round of metal-core PCBs for the LEDs. Designed an 8 channel driver board based on the L3414, a different sketch from the original planning Machined a single heat sink, and did test mounting of the emitter board. Populated one emitter board. Read more

July 6, 2015

Service Discovery: One, Some, or All


Service Discovery, to use the basic definition, is the mechanism in which services, residing at a non-static address, can be found on a computer network. There are, in a basic nutshell, three types of service discovery, modeled after how they offer their service endpoints to the clients. This set can be reduced to two types in most real world scenarios. Service discovery systems are designed to return endpoints, a list of one or more logical host and/or host:port or even URL lists. Read more

January 31, 2015

Design Log: LEDBrick Aquarium LED Lighting


This design has been on my back-burner for quite awhile, but its time to write it up and continue pressing on. I really like reef aquariums. I currently have a (modest) 90 gallon system, which has livestock dating back to when I started keeping salt-water systems in college (circa 2004). How I managed to actually afford keeping a salt-water system in college is beyond me, but things have progressed nicely. Read more

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