When you want to see the stars, find someplace dark
It is always a sick feeling in the gut when a drone goes down.
This time it was an unseen branch, a thin and leafless thing that reached well out from the tree, unseen until it was too late. Unseen by the drone’s obstacle avoidance system as well.
I crashed the drone at Panther Falls while enjoying a waterfall day in Southern Washington. A place deep in the trees where a drone pilot is advised to exercise caution. I did, and crashed it anyway.
Continue reading “Crashed and Repaired”
Designing and building equipment for aquaculture means I use controllers. Quite a few controllers, dozens upon dozens of them, little boxes meant to keep some parameter in range. Temperature, pH, water level, whatever, a little box with a display, a few buttons, and a relay in the back to turn something on when needed to control the outcome.
Industrial suppliers will sell you a controller for just about anything, there are catalogs full of them, from inexpensive to thousands of dollars you can buy the solution to your needs. Buy one, wire it in, adjust a few setpoints and you have everything under control.
Enter the STC-1000, a little cheap temperature controller found on eBay, Amazon, everywhere. It comes in a bunch of different versions, need readout in Farenheight or Centigrade? No problem. I have no idea who makes it, some asian factory somewhere. It is available in a hundred different brand names from hundreds of different sellers for somewhere between $12 and $25, all absolutely identical as far I as can tell.
The STC-1000 is cheap. Cheap enough that I am somewhat suspect of their reliability. I do not buy them for production line bioreactors and grow tanks, places where I cannot trust a cheap controller with a few thousand dollars worth of product. For critical uses I buy full industrial rated temperature controllers from a reputable supplier for around $100 each.
But for experimental setups? Temporary research hacks built with more limited budgets? There are a couple dozen of these STC-1000 controllers around the place. They are easy to use with simple configurations, seem to be accurate holding calibration, and I have not had one fail yet.
So how do you sell a device like this for about $15?
Time for a little deconstructive analysis…
Continue reading “What is safe?”
pH measurement is a quirky and often frustrating technology. Usually working well, they can go wrong in so many ways. With dozens upon dozens of pH probes in service on the cultivation pads I have now spent a few years attempting to discover all of the ways a pH measurement can go bad.
A voltage generated by ion exchange across a glass membrane is the magic that makes a pH probe work, simply measure the voltage and you can measure the hydrogen ion activity of a solution. The result is a number from 0 to 14, with numbers less than seven being acid, and numbers above seven being basic. Most aquatic or marine life, such as healthy algae require conditions close to 7, or neutral, too acid or too basic and everything dies.
Continue reading “An Open Source pH Probe Simulator”I have owned this stereo microscope since I was a teenager. At first used for examining rocks and minerals in my collection, it has found many uses over the years, mostly used during assembly and inspection of various bits of electronic gear. It has been a workhorse microscope, well used, and well loved.
Despite this it bit me!
I know the feeling all too well, that little 60Hz nibble of 120Vac electrical power, a feeling anyone who has worked with electricity like I have recognizes instantly. Somewhere in this microscope 120Vac power is shorted to the frame.
Continue reading “LED Microscope Lights”For someone who works with their hands tools are important. We all have our favorite tools, that one we always use as we have for so many years. There may be a dozen screwdrivers in the rack, but that one is used almost every time.
Thus is with great sadness that I announce the death of my longtime soldering station.
A good soldering iron is a basic tool for an electronics engineer. A multimeter, a soldering iron, and a set of basic hand tools are absolutely necessary for any electronics workbench. To this end I had bought a very good iron, one that has served me well for several decades.
I wonder just how many soldered connections I made with this old soldering iron… Thousands upon thousands certianly, so many circuit boards, connectors, and wires.
There are no available spare parts for this long obsolete soldering station. There are many conversations on bulletin boards and chat rooms lamenting this as others have had their beloved soldering irons fail. The WES50 was long ago replaced by the WES51, and the parts are not interchangable.
With sadness I remove the old soldering station from the bench. I replace it with a new Weller WE1010NA station. I wonder just what work awaits the new soldering iron, how many solder joints will it see in the coming decades. I hope that this new iron will outlast me.
Looking at the catalog I look at a price that is just too high. A few bits of molded plastic for almost a hundred dollars? You are kidding? Right?
Well? I need this. Actually I need a few of them.
This is when my frugal nature hits hard… I can make that.
Continue reading “Yeah, I can make that.”Leaking alkaline batteries, the bane of our portable, battery powered existence. All too many times I have found myself repairing electronic devices damage by leaking batteries, or just junking the gear when the damage is too severe.
This time the device in question was just a bit too valuable to dispose of despite fairly extensive damage.
A Celestron Nexstar 8SE telescope.
Continue reading “Battery Corrosion Again”In the back of a plastic crate, forgotten for a decade or three, a little cardboard pack holds a few battery holders. A humble package, not containing anything particularly special, yet this is a time capsule from another age, another me from decades ago.
This little package brings back memories… I remember when shelf after shelf of components were packaged this way. The look, the smell, the facination with the fantastic array of parts on display in those little packs, each inspriation for a project or solution. The young teenage me wandering those shelves wondering what I could do with those components.
Continue reading “A Time Capsule Package”The usual drill… A problem that can be solved by a bit of circuitry. In this case the gals in the lab were having trouble controlling the mix of gas to their cultures. They needed to feed much less CO2 to the mix, where the off-the-shelf flow gauges and needle valves became difficult to use much under one liter-per-minute.
Simple solution… Build a gas modulator, something that could turn on the gas some percent of the time, allowing easy control of small amounts of CO2 to the mix. A timer and a gas solenoid… Easy.
There is nothing particularly interesting about the circuitry. A seven segment display, a few switches, and a power transistor to control an external solenoid. All very basic. It is the controller that is new, at least for me. An Arduino provides the programmable part of this project.
Continue reading “A Gas Modulator”