September 18, 2020

Design Log: blueAcro Power Bar and Sensor Updates

Some updates for products over at - mirroed from Reef2Reef I have basic power boards already designed up, and a few sample cases in house. The form-factor is nice, though slightly tall compared to your average power strip. Probably not a major issue, as its a fair bit less wide. I’ll report back when I have some first samples assembled. The power board has a number of provisions, including protection for the relay contacts with inductive loads, without using a plain MOV or other circuit which leaks power. Read more

April 8, 2020

theatrus' Perfect Temperature Controller - Temperature Sensors

Let’s talk temperature sensors, at least let’s talk about the guts of a temperature sensor and less about the housing, cables, etc. There are three main varieties you’ll find in your typical “probe” style sensor, and a fourth I’ll mention because its common for integrated circuits. I’m considering “relevant reefing temperatures” to be about 75F to 83F - sorry, I haven’t switched to metric on temperature just yet, even though I reference them below. Read more

April 8, 2020

theatrus' Perfect Temperature Controller - The Overview

I’ve been keeping aquariums of all flavors for a very long time, and have seen and first hand experienced what happens when our lovable basic heaters (and chillers) run amok and fail to do their jobs correctly. Even worse, we often decide to go whole hog into the aquarium controller systems, which promise us web graphs and e-mails, while also being in charge of critical functions such as temperature and top-off, mixing software and control domains that should never be mixed (e. Read more

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 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 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 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

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