electronics – A Darker View

What is safe?

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…

Workbench Mess

The usual mess on the electronics workbench

3D Printed Fix… Again

It has become apparent to me that what were modern electronics in my youth are now considered vintage electronics. What does that say about me?

The piece of vintage electronics in question this day is a veteran Tektronix 465 oscilloscope. This particular oscilloscope was purchased decades ago as surplus from Elliot Electronics in Tucson, once my go to place for electronic parts and tools.

The ‘scope is in great shape… Mostly.

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.

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.

Midnight Run

The phone rang just as I was going to bed.

This phone call had a number I knew all too well, even without the caller ID showing the name… K1 Remote Operations. A this time of night it would be a problem, a serious problem. This particular problem would have me on the road back to the summit an hour later.

Keck at Night — Looking towards the Keck 2 dome on a moonlit night

Midnight runs to the summit are not common, but they do occur in my life. Usually we can work remotely, the night attendant serving as our remote eyes and hands. Just press the right button, flip the correct switch, done. Not this time. We tried, for over an hour we tried.

I really did not want to head back up. I had just gotten down a few hours ago, having spent the day on the summit working on the usual long list of things that need to get done. Days on the summit, in the thin air of nearly 14,000ft elevation are physically draining.

The irony of this malfunction is that I had seen it before. The dome had tripped out inexplicably on previous occasions. The problem would occur then disappear. Once it vanished you could not troubleshoot it. Unlike most of our other systems there are no logs from the shutter drive, nothing records what was going wrong.

The Friday before this it had happened to me again. But this time was different, I had a maintenance computer attached to the PLC serial port. This time I saw the error, something in the code labeled speed mismatch. No idea what this was, or how it worked. Again the error disappeared, and I could not troubleshoot further as the weather was getting worse. No opening the shutters again.

I needed a chance to figure out what this fault was… Later that day I read through the code, figured out this feature was a speed check to insure that both sides of the shutter are driven evenly. A check to compare the right and left sides of the shutter and to fault if the difference is too large. Two words of memory were compared, if the difference was too large it faulted the shutter drive.

Logic

Flasher Fun

With the Keck Observatory open house approaching I am helping get one of the most popular activities ready. At the last two open houses we have made flasher pins, we will do so again this year.

A simple electronics project… The Flasher Pin

Flashers? These are a simple circuit built on a PCB that flashes a pair of LED’s. Nothing serious, just a bit of electronics fun. The activity allows folks to learn a little electronics and soldering.

The PCB is configured as a pin or badge, with a brooch pin soldered to the back that also serves as a switch to turn on the LED’s.

The original design came from John Maute at SAO. The circuit is based around the venerable LM555 timer IC configured as an astable multivibrator. The LM555 timing circuit is simple enough to solder together in a few minutes, complex enough to look cool and provide a real introduction to an electronic circuit.

Continue reading “Flasher Fun”