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
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.

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Consequences of a Bad LED

A bad indicator LED, a simple ten cent part brought the Keck 1 telescope to a stop this last week.

Logic Card
A section of the AAA logic card.
How can that be? Usually an indicator is just that, an indicator. While an LED may indicate a problem it is rarely the cause of the problem.

I was getting ready to leave the summit when the radio started to speak words of concern, it sounded like something was not working, an instrument rotator?

Worse, the Keck 1 computer room hosted a veritable crowd, from the summit supervisor to all of the techs. Yeah, this was not good, why are they all looking at me? Oh, h%#*!

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Old School Drive Corrector

Telescope clock drives from the 1980’s or earlier often used AC synchronous motors. These commonly available AC motors are used to power timeclocks, record player turntables, and telescopes, anyplace a motor needed to run at a very accurate speed.

Sidereal Drive Platform
A Celestron telescope drive configured as a sidereal rate tracking camera platform
The speed of a synchronous motor is set by the frequency of the powerline, in North America and many other places this is 60Hz. As the frequency must be synchronized for every power station on the grid the frequency is quite accurate, a feature exploited by clockmakers and telescope builders. Once found everywhere these motors are less common, but are still around.

Drive Correctors

It was the common use of these motors in telescope drives that led to the invention of the drive corrector, a device that was once a required piece of kit for serious amateur astronomers. Drive correctors like this were needed when operating from a battery at some remote location, generating AC from a 12Vdc car battery.

You also needed a drive corrector for guiding while doing astrophotography. The corrector could speed up or slow down the telescope drive a bit to correct the telescope drive speed and stay on target, something not possible with the fixed 60Hz of the mains supply. Thus the term drive corrector.

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Little Padded Envelopes from China

Hardly a week goes by without some little padded envelopes in my mailbox. 16×2 LCD character displays, 74HCT541 IC’s, 6mm encoders, some 10mm spirit levels, a couple more ESP-01 modules, and that is just this last month. Living on an island in the middle of the Pacific, there is no place I can buy electronic components. I must order everything.

Little Padded Envelopes from China
Little Padded Envelopes from China
Those envelopes often arrive from places like Hong Kong and Shenzen, China. I find them on my desk where Deb just drops the latest little shipment from the other side of the planet.

The surreal part of this is that it is even conceivable that it would be cost effective to buy components from halfway around the globe like this. Not only is it affordable, but it is easy. It is easy to locate the correct components , it is easy to pay for the items, and it is easy to ship the parts across oceans.

Just a few years ago, buying products like this would have indeed been an insurmountable challenge, now it is routine. The internet and electronic storefronts like eBay that make shopping easy.

Electronic payment networks, notably PayPal, that make payment easy. And a global shipping network capable of getting those little padded envelopes to the correct location. For anyone familiar with history these networks are simply stunning in their capability, something inconceivable even a few decades ago.

Some would question the quality of components from China. You do need to be careful, but unlike cheap consumer goods, electronics components are usually quite acceptable in quality. I have had very little trouble ordering from Asia, the items perform as advertised.

I would probably not order from China if building life support equipment. For my little electronics projects the stuff works. Just check the seller’s ratings and record, then press ‘Buy it Now’.

One More RadioShack Closes

Our local Waimea RadioShack shop is closing.

RadioShack Pile
A pile of RadioShack components purchased at the local closing sale.
Our local RadioShack has survived several rounds of store closures as the chain has moved in and out of bankruptcy court. Time has finally run out for the store and it is liquidating the stock and will close by the end of the month.

I have commented on my view on RadioShack before. As an electronic hobbyist I have mixed feelings about RadioShack. In my younger years it was a decent place to buy electronic components. Some of the early computers I learned on were RadioShack products like the TRS-80 and Tandy 1000. I even worked as a RadioShack sales clerk one summer during high school.

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Observatory Still Life Gallery

Often you just need to take note of the small scenes that make up daily life. Over the years I have made an effort to photograph these scenes, there is so much richness in our everyday existence that too many do not notice…

GenPIC, A Microcontroller Utility PCB

Over the years I have hand wired so many microcontroller PCB’s. Along with my own projects for myself there are more than a dozen of my little microcontroller devices at work about the observatory. The OSIRIS IR calibration source, the Keck 2 dome inclinometers, a precipitation sensor interface, the Keck 1 AO electronic vault temperature sensors, the weather mast fan and shelter controller, the list goes on. Anyplace a bit of electronic intelligence is needed for the task.

GenPIC
A PCB assembly in layout
Of course the challenge is that each of these controllers has been hand wired and built for a specific task. This takes a few hours of running little wires on a perfboard. And while I enjoy such wiring, it does make the task take notably longer.

While a couple of my microcontroller designs have been laid out on proper circuit cards, like the SciMeasure camera exposure controllers, I have never laid out a general purpose microcontroller PCB. This is not for lack of thinking about it, so many times I have considered this could be so much easier if I could only invest a little time in a layout.

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