Electronics – A Darker View

An Open Source pH Probe Simulator

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.

pH Sim 2 in use checking a Symbrosia Controller

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.

LED Microscope Lights

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.

An American Optical model 40 stereo microscope

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.

Favorite Tools

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.

A veteran Weller WES50 soldering station

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.

Yeah, I can make that.

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.

Battery Corrosion Again

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.

Corrosion damage in the base section of a Celestron 8SE mount

This time the device in question was just a bit too valuable to dispose of despite fairly extensive damage.

A Celestron Nexstar 8SE telescope.

A Time Capsule Package

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.

Skin pack holding a set of battery holders from another era. — A set of battery holders in retro packaging

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.

A Gas Modulator

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.

SO2 Monitoring Station

Living with active volcanoes about becomes a bit easier if they are properly monitored. The entire island of Hawai‘i is liberally equipped with sensors of various types… Seismographs, tiltmeters, GPS stations, cameras, and gas monitors.

I came across one of these last instruments on a recent visit to Hawai‘i Volcanoes National Park, the new Kahuku Unit at the south end of the island. While walking in the gorgeous natural scenery of the park, this engineer was instantly attracted to a spindly frame of tubes standing in an old corral.

The Kahuku Cross Fence station is part of the NPS maintained Hawaii SO₂ Network with stations throughout the park. The data is provided to rangers and posted on the park website to advise visitors of volcanic gas hazards while visiting the volcanoes.

Working on it…

Schematics, notes, and tools scattered beside the work area... — Schematics, notes, and tools scattered beside the work area…

Keep it Running

Some equipment around the observatory is thirty or more years old. As you would expect, keeping it running can be a challenge.

A redesigned small signal PCB for an Inland Motor FCU-100-30 amplifier power supply

There are two ways of dealing with this old equipment… Replacing it with something new is the preferred way. When it becomes difficult to locate spare parts, when it breaks down too often, just replace it with new gear. For much of the equipment this is the usual answer and is often a major part of the job.

Some equipment is not so easily replaced. When replacement would require wholesale redesign of a system it becomes more of a challenge. Sometimes the only choice is to keep that old gear running.

This is the case with our servo amplifiers. Twelve amplifiers supply the power that drives the telescope, one amplifier for each motor. Eight amplifiers and motors drive azimuth, four drive elevation. Three hundred and seventy tons moved by twelve relatively small DC motors. While much of the telescope control system was recently replaced, it was decided to keep the old servo amplifiers.

You might notice that these servo amplifiers are just a wee bit critical.