Michael A. Covington    Michael A. Covington, Ph.D.
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Popular topics on this page:
Motorola 3360 "Internet" LED never lights up green
How to fix electronics when batteries have leaked
Your software should not be a large part of our lives
Are dollar-store batteries any good?
Should we boycott shopping on Thanksgiving?
Prevent PRO-95 scanner from overcharging batteries
Car key remote transmitter mysteriously loses range
Other logics (nonclassical reasoning)
The lost art of electronic repair
Moon (entire face)
Moon (entire face)
Moon (Tycho and Clavius)
Moon (Alphonsus and Rupes Recta)
Moon (Apennines)
California Nebula
Double Cluster
Helix Nebula
Andromeda Galaxy (M31)
Galaxy M33 in Triangulum
M52 and NGC 7380
Mu Cephei region
Comet Lovejoy C/2013 R1
Comet Lovejoy C/2013 R1
Comet ISON C/2012 S1
International Space Station
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Short notes

As my consulting business ramps up to at least 100% capacity at the beginning of December, I'm going to close out the month with a few short notes.

I've revised my earlier notes about shopping on Thanksgiving as it became evident that the people opposing it didn't have the same thing in mind that I did. We agree that a certain amount of commercial activity helps people have a better holiday. It's not a Sabbath on which all work is forbidden. The Black Friday shopping frenzy, however, is for the birds, whether or not it spills over into Thursday. It smacks of of replacing a holiday in honor of God with a frenzy in honor of Shopping.

In other news: I said Bitcoin would get hacked when the stakes got high enough, and it did. The people running it were overconfident.

And a last note on Comet ISON: As of this moment, we don't know what it's going to do next. At least part of it survived perihelion passage and will reappear in the morning sky, probably not as a spectactular sight, but hopefully as something I can photograph.


Other logics — nonclassical reasoning

Are there any respectable and useful kinds of logic other than the standard one?

The answer is yes, and in fact a good bit of my research has been connected with this question.

Here's a talk I've given several times. Click through and read the slides.

The lost art of electronic troubleshooting and repair

In my youth, I learned a lot about electronics from books about how to repair radios and TVs. The 1960s were the height of the TV repair era, and component-level repairs were frequenly needed.

But another force was at work. Recently, in an old magazine, I came across someone around 1958 opining that cheap, reliable silicon transistors would result in "disposable appliances" — our radios and TVs would work so well, and be so cheap to make, that we would simply throw them away and get new ones when the time came. Minor failures would no longer happen, and a radio or TV wouldn't die until something big, like the picture tube, bit the dust.

That prediction was exactly right, of course.

But many of us feel that the pendulum has swung too far. It may not always be economical to repair equipment at the component level, but the art of doing so should be preserved, for several reasons:

  • Respect for craftsmanship. I know economics dictates it, but I still feel a twinge of sadness when something elaborately and beautifully made is thrown away.
  • Sometimes economics tilts in our favor. We would at least like to be able to screen "trash" for things that might be very easy to fix. Sometimes a $200 gadget gets junked when all that is wrong is one broken cable. Some people might be glad to get a good stereo for $5 and an hour's labor.
  • Sometimes there is a real need. Just like people who restore antique cars, some of us put a high value on keeping old electronics alive. Sometimes a particular piece of equipment has historical or sentimental value even if it is not rare. For example, I'm going to try my best to repair my father's Hallicrafters shortwave radio from the 1950s, even though its performance will never be more than mediocre by today's standards. (Today, a $140 Sony is one of the best shortwave radios ever built and will outperform any old-technology receiver.)
  • It's satisfying. Although I haven't had much time to put into it in recent years, I've always enjoyed bringing an old piece of equipment back to life. The antique-car community has similar feelings and motives. There are beginning to be 100-year-old cars that are still roadworthy, and 75-year-old radios that still work.

Industrial and medical electronic repair is, of course, still a thriving art. It's consumer electronics that have been left out.

So where do you learn how to fix things? Around 1980 to 1990, a lot of mediocre books were published — experienced writers were asked to write about new technology, and they had so little experience that they didn't tell us anything unobvious. But since then, two high points have appeared.

One is Sam Goldwasser's Repair FAQ, although it's looking a bit dated by now — the pace of updates has slowed. Read it; save a copy.

The other is this book, which I've just read with interest and enjoyment. The author, Michael Jay Geier, is a lot like me — he was running a repair business when he was 8 years old — I could fix things when I was 8 but didn't think of making money doing it. He shares a lot of practical knowledge about what components are likely to fail and how to test them.

By the way, from that book I got one technique that was genuinely new to me: "current flooding." If a piece of equipment has a short circuit across its power supply, causing its power supply to shut down, the short can be almost impossible to locate. But "current flooding" provides a way. Disconnect the original power supply and connect a lab supply, set to the right voltage, capable of delivering many more amps without shutting down. This will fry the shorted component, often making it actually catch fire, and won't damage anything else because the correct voltage has never been exceeded. Shorts to ground are a common fault in cards for PCs — the symptom is that the PC won't boot with the card installed — and I would have used this technique a few months ago if I'd known about it.

Suppliers of electronic parts have started to look better, too, and just as in the 1960s, they've gotten in touch with hobbyist ("maker") culture. Look for instance at MCM Electronics and Parts Express (which has to add a hyphen between "parts" and "express" in its URL because some search engines were objecting to a certain sequence of three letters!).



Thanksgiving à trois

Melody, Sharon, and I are celebrating Thanksgiving together. Our extended families are gathering elsewhere, and of course Cathy, Nathaniel, and Mary are up in Kentucky. I'm looking forward to a day off work.

We have much to be thankful for. Without going into detail, several family members have a good prospect of overcoming some chronic health problems. My consulting business is up and running. We have a granddaughter who is nearly a year old. All around, things are looking up.

I also want to wish all my friends (not just my Jewish friends) a blessed Hanukkah, a holy day that commemorates events that are an inspiration to freedom-loving people everywhere.

Field of Mu Cephei

To conclude the series of astrophotos taken November 3, here is another view of the field of Mu Cephei, with the large, mysterious-looking red nebula (compare last month's photo). This is a stack of fifteen 1-minute exposures, Sigma 105/2.8 lens, Canon 60Da at ISO 3200, iOptron SkyTracker, at Deerlick.


Car key remote transmitter mysteriously loses range

A couple of months ago, the key remote transmitter for my Ford Escape mysteriously lost range. It used to work reliably from 50 feet away, or more. Suddenly, depending on the location, I often had to walk right up to the car in order to get it to respond.

I replaced the battery in the transmitter, but that didn't make a difference. And Melody's transmitter was just as afflicted as my own.

Today (Nov. 26) I had a flash of insight. The trouble started when I started keeping my GPS device plugged in all the time.

So I unplugged the GPS from the lighter socket, and that was that! The transmitter has regained its old range.

Presumably, either the GPS itself or the power supply is producing RF interference. I actually suspect that the cheap lighter-socket-to-USB power supply is the problem; it's not the one that originally came with the GPS device. Next experiment: Go back to the original power supply for the Garmin Nuvi GPS. It probably has better filtering.

[Update:] The problem is present whenever my Scosche brand dual USB power adapter is plugged into the lighter socket (which is energized all the time). It doesn't matter whether the GPS is plugged into it. I don't know if this adapter is defective or if this is a design problem with it. More news soon...



How to prevent a Radio Shack PRO-95 scanner from overcharging its batteries

Here's the gadget I built this evening (Nov. 25). I had gradually become aware that my Radio Shack PRO-95 scanner radio overcharges its NiMH batteries. That is, whenever it's connected to its 9-volt power supply, it pumps 160 mA into them, which is too much for continuous trickle charging.

So I inserted this gadget in the 9-volt power line between the radio and the power supply ("wall wart" — incidentally, it's an old Sony one and outputs 9 volts). At the flip of a switch I can either charge the batteries (with 160 mA) or maintain them on a trickle charge (30 mA).

On "maintain," it charges the batteries very slowly and can continue indefinitely without harm. This is for topping up batteries that are only slightly run down. It would take a couple of weeks to charge a completely empty battery. Also, on "maintain" there is not enough current to power the radio; you can't listen to it.

On "charge," the batteries charge completely in about 12 hours but would be damaged if the charging continued for days. This is also the setting for listening to the radio with the power supply plugged in.

What's more, the red LED lights up on "charge" to remind me not to leave the switch set that way indefinitely. I built the gadget in an old translucent plastic 35-mm film can (remember those?) so that the LED is visible from all directions.

Like all my published electronic circuits, this is intended for people who understand how and why it works. It's not intended to be built blindly.

In other news: My technical accomplishment for November 24 was soldering under a dissecting microscope in order to fix Sharon's Intuos graphics tablet. The tiny USB connectors are soldered to the printed circuit board and can be ripped loose any time anything tugs on the cord hard enough to peel the copper traces off the board. After my repair, there's some epoxy helping to hold things together.

And I'm quoted in Popular Mechanics. Somehow, a rumor got out that Wolfram Research had invented a way to write computer programs in plain English. My take? That doesn't seem to be what Wolfram is claiming, and anyhow, it's not a good idea. We don't use plain English to express algebraic equations, or house plans, or musical scores. English just isn't precise and concise enough; special notations are much better.


From M52 to NGC 7380

A rich Milky Way field in Cassiopeia and Cepheus, showing the star cluster M52 at the upper left and the (red) nebulae Sh2-157 and NGC 7380. Same technique as the picture I presented yesterday, but only 5 exposures were stacked, and the picture is presented with rather high contrast to bring out the faint nebulae.


Galaxy M33 in Triangulum

Another example of galaxy photography with inadequate equipment under excellent conditions. This is a stack of 13 one-minute exposures with a Canon 60Da at ISO 3200, using a Sigma 105-mm f/2.8 lens wide open and an iOptron SkyTracker, at the Deerlick Astronomy Village.

This is another of my pictures from November 3, and there are still more to come!



Chilly reptile

This lizard was contentedly basking on a fence in our back yard when the temperature read 48 F on my own thermometer and 45 F at the Athens weather station. This may be the same lizard that was our temporary pet last December.

[Addendum:] This is indeed an American chameleon, Anolis carolinensis. He can change color, and in the chilly air, he turned so brown as to practically disguise himself as a fence lizard, Sceloporus, whose behavior he also seems to be imitating.


Andromeda Galaxy (M31)

I've photographed the Andromeda Galaxy many times before, but this might be the best example of a good picture taken with a small aperture. Same technique as the picture of the Helix Nebula that I presented yesterday (below); with a 105-mm lens at f/2.8, the total clear aperture was 1.5 inches. Compare that to the 200-inch telescope on Mount Palomar...


Helix Nebula

This is the Helix Nebula (NGC 7292) in Aquarius, photographed with inadequate equipment — but still, I got something. Stack of six 1-minute exposures, Canon 60Da, ISO 3200, Sigma 105/2.8 lens wide open, iOptron SkyTracker, postprocessed with DeepSkyStacker and PixInsight. The pixels were binned to make one pixel out of every four, and you are looking at the central 600 × 400 pixels.


C. S. Lewis, 1898—1963

Plaque unveiled November 22, 2013, in Poets' Corner, Westminster Abbey
Photo by Michael Ward, used by permission

We commemorate the death 50 years ago on this date of C. S. Lewis, scholar, poet, and defender of the Christian faith.

Tech notes

Ghost story: My Asus laptop won't turn on when it's resting on top of my folded-up Lenovo laptop.

The reason? Both of them use magnets to sense when the lid is closed, and the Asus is fooled by the Lenovo's magnet. At least, that's my best guess.

Fixing up old gear: In the next few weeks I'm going to be repairing and maintaining some older electronic equipment in my workshop (such as the Fabulous Fifties audio generator).

Here are a couple of hints about parts.

(1) For replacing resistors in vacuum-tube equipment, I recommend Yageo 2-watt flameproof resistors, which are rated at 500 volts and cost about 20 cents apiece at Digi-Key. They are hardly any bigger than traditional half-watt resistors. Most modern resistors are rated at only 1/4 or 1/8 watt, 250 volts maximum.

(2) I am going to replace every electrolytic capacitor that is more than 30 years old, even if it seems to be working perfectly. I have some in use, in equipment, that are more than 60 years old! Unfortunately, there is a real risk that they will fail catastrophically and take other components with them when they go. And modern capacitors are much higher-grade than the older ones were even when new.

Since it does no harm for filter and bypass capacitors to be higher in capacitance and voltage than originally designed, I'm not going to try to match them all. Instead, I'm buying 47-microfarad and 22-microfarad, 450-volt, capacitors in quantity.


The Double Cluster in Perseus

Now back to the pictures I took on November 3 at Deerlick. This is the Double Cluster in Perseus (at the bottom) and, above it, some faint emission nebulae (hydrogen gas clouds, red) and also some dark nebulae (dust clouds obscuring the more distant stars). Stack of twelve 1-minute exposures, Sigma 105-mm lens at f/2.8, Canon 60Da, ISO 3200, iOptron SkyTracker.


The lunar Apennines

"Can you see any mountains from your home in North Georgia?" friends sometimes ask. Yes — these, for example — they're on the moon. The lunar Apennine mountain range is named for a mountain range in Italy. Like other recent moon photos, this is a stack of about 1300 video frames taken with a Canon 60Da and a 5-inch telescope on back on November 11.

Happy birthday, Sharon!


The astro-tree

A couple of years ago, we had some trees taken down near my telescope pier, only to find that we were relying on them to block some lights farther up the hill. Today I had a tree planted that will, in a few years, do the same job again. It is a Cryptomeria of some sort.


Should we boycott or ban shopping on Thanksgiving?

[Revised again.]

This year, several major department stores are going to be open on Thanksgiving Day. This announcement has aroused controversy. Should this heathen practice be boycotted or banned?

Well — I'm not planning to shop on Thanksgiving. I've always shied away from artificially-created "Black Friday" frenzies, and this sounds like more of the same.

I suspect not many people will want to shop on Thanksgiving.

But I'm not going to circulate pledges or demand boycotts or bans. I want to point out that there is another side to the story.

Let's not forget that we rely on a certain amount of commercial activity for the benefit of everyone. Gas stations and some restaurants and pharmacies stay open. Nobody objects to TV stations or the NFL working and making lots of money on Thanksgiving. It can be quite inconvenient if too many businesses shut down — I remember having trouble getting something to eat one Thanksgiving when I was in college a long way from home, and of course all the college staff got the day off and all the local businesses closed.

So let's not talk about activity on Thanksgiving Day as if it were Sabbath-breaking.

I think the people who are against "shopping on Thanksgiving" are aiming at slightly the wrong target. The real risk is the abolition of Thanksgiving itself, not some kind of secular Sabbath violation. I'm alarmed by the way "Black Friday" seems to have spread to England (even though Thanksgiving is not a holiday there) and the calls to make it an official holiday in some states. A holiday to honor God (or at least our human benefactors) is being replaced by an artificial commercial frenzy.

The real problem is the Black Friday circus, whether or not it spills over to the preceding day.


Alphonsus and the Straight Wall

Another moon picture, again a stack of about 1300 video frames taken through my 5-inch telescope on November 11. The crater just left of center, with a single central peak, is Alphonsus, named in honor of King Alfonso X of Castile (Spain), patron of astronomy.

At the lower left you see the Straight Wall, which is not a wall but a cliff and is correctly described by its Latin name, Rupes Recta.



Should you use bargain batteries?
Are cut-price dollar-store batteries any good?

A name-brand 9-volt battery like the one on the left costs about $3. The one on the right cost me 50 cents, or rather 2 for $1, at a dollar store. Which one is the better deal?

Well, the one on the left contains about 6 times as much electricity. It also costs 6 times as much. And it's from a manufacturer with a proven record of reliabilty. (Sunbeam is just an importer; we don't know who makes their batteries.)

So the one on the left is the better deal. Right?

Maybe, maybe not. It depends on how you're going to use the battery.

If you're going to use up the battery in a high-load device, then definitely buy the better one. High-load devices include anything that plays music through a speaker, runs a motor, or produces more than momentary light or heat. Camera flashes are high-load devices because although the flash is instantaneous, it is very bright. Cameras are high-load devices because of the focus motor and the bright display.

And always use top-grade batteries in smoke alarms.

But if the battery is going into a low-load device, such as a clock, calculator, or multimeter, or will be used only occasionally, as in a penlight or test instrument that actually runs only for a few minutes per year, the cheaper battery may be the better buy. Either battery is probably going to die of old age rather than by being used up.

And if the battery is likely to be run down by someone accidentally leaving the equipment turned on, not actually using it, you might opt for the cheaper battery, even in a high-load device. (This is often the case with toys.) If any battery is doomed to be exhaused accidentally, you might as well make the accident less costly.

A word of caution: don't leave a battery in place for months after it has been partly run down by a high-load device. That's what makes them leak. Partial exhaustion by a heavy load, followed by age, leads to leakage.

I've never seen a 9-volt battery leak. Its cells are enclosed in a rectangular box. But 1.5-volt batteries leak, in my experience, more readily now than they did in the 1970s! You are handling the cylindrical cell itself; it's not in a box.

By the way, the cheapest batteries you can buy today are equal to the best ones you could buy in 1970. Sunbeam is not lying when they describe their 50-cent battery as "super heavy duty." It is equal to the "heavy-duty" carbon-zinc batteries of 40 years ago.


Your software shouldn't be a large part of our lives...

Important advice for software developers, paraphrased from the book Code Simplicity, by Max Kanat-Alexander:

The software that you are developing is a large part of your life. It shouldn't be a large part of ours.

That is, don't expect us to spend a year learning how to use it just because you spent a year developing it.

Instead, spend a year making it fit our needs so well that we only have to spend a minute learning how to use it.


C5 Moon

This will provide some context for the images of lunar regions that I took on November 11. This is the full face of the moon with the same telescope during the same observing session. One image of a smaller region appeared here two days ago; the others are coming.

This is a stack of 8 exposures taken with the camera direct-coupled to my old Celestron 5. Because of field curvature, the picture is sharper at the center than at the edges; I focused on the center, which was probably a mistake, since "compromise focusing" on an off-center area might have yielded a picture that was acceptably sharp all over.

Compare this to the picture taken with a big telephoto lens a few days earlier — but the comparison isn't entirely fair because the air was considerably steadier for this newer picture.


King Lear and some short notes

I wish I could go, but I'm stuck in Georgia... The cultural highlight of Lexington, Kentucky, this week is Shakespeare's King Lear, performed by the Actors' Guild of Lexington, with my son-in-law, Nathaniel Barrett, playing the role of Edgar. In the picture, he's the one in the middle.

Speaking of things theatrical, when I was taking pictures of the comets on the morning of November 11, I stepped out into my backyard wearing slippers, pajamas, and a dressing gown. A particularly big, fancy, royal-looking dressing gown that I've had for years; I had it at Cambridge thirty-five years ago, where it looked like (and was mistaken for) a foreign academic gown. So I felt a bit like Tycho Brahe, who reportedly observed wearing the full regalia of a nobleman.

The battery charger that I described recently was reviewed in QST, April 2009, and they really liked it. Although Chinese-made, it is an American design.

QST also tells me that the most unreliable part in modern electronic equipment can easily be the solder, especially if the equipment failed after being exposed repeatedly to vibration or changes in temperature. Everything else is so reliable nowadays that a broken piece of metal is actually likely to be the problem! Gone are the days when your TV needed a new tube every few weeks.

An advantage of an analog oscilloscope that I didn't mention — and the reason the digital one will never do all the work — is that an analog oscilloscope responds instantly, while a digital oscilloscope often takes a visible fraction of a second to process and display a waveform.

That means you need an analog scope if you want to see a change instantly. An example arises when looking for loose connections — the analog oscilloscope will tell you whether changes in the signal are synchronized with your tapping on the circuit board; a digital oscilloscope won't.


To the moon!

The evening of November 11 was shaping up to be the last (moderately) warm evening of the year (47 F), and ClearSkyChart was predicting "good seeing" (steady air), so I got out my old Celestron 5 (now a third of a century old) and let it cool down to the temperature of the surrounding air.

Then I photographed the moon and got very good results. I'll unveil the pictures one by one as this month goes by — along with more pictures from my last trip to Deerlick — but here's one to get started with. This is the southern region of the moon, with the craters Tycho and Clavius prominent at the left. Stack of about 1300 video frames taken with a Canon 60Da.


Comet with tail

Here's that same picture of Comet Lovejoy, processed a bit differently to bring out the faint tail.

Free audio editor

Commercial software is getting serious competition from free software — and the latest one I want to try is Audacity, an audio editor. It includes a tool for removing the noise from vinyl records. I have yet to try it, but I'm going to. Because of patents, you have to get add-ons if you want to handle MP3 files, but they, too, are free.


Two comets and the ISS

Offhand I can't remember observing two unrelated comets in the same short observing session, although I suppose I've probably done it before now. This morning (Nov. 11) I got up at 5 a.m. and carried the iOptron SkyTracker out into the yard (with one hand), then put my Canon 60Da on it, with a 105-mm f/2.8 Sigma lens wide open.

Here's Comet Lovejoy C/2013 R1, which is about sixth magnitude and is a fine sight in binoculars. This morning it was near the star Kappa Leonis. This is a stack of four 30-second exposures. You're looking at an enlargement of just part of the picture.

And here's Comet ISON C/2012 S1, the "comet of the century" that is shaping up to be nothing of the sort. I couldn't even see it in binoculars (under unfavorable conditions). This is a single 30-second exposure, enlarged and cropped.

This is in the field of the star Eta Virginis.

After I photographed the first comet and before I photographed the second, the International Space Station flew over, looking like a second Jupiter moving across the sky. I took a 30-second exposure, showing it as a trail:



How to fix electronics when batteries have leaked in them

I've just rescued my venerable old Nikon Coolpix 990 (my first pro-grade digital camera, circa 2002) from a horrible fate, and to celebrate, I used it to take the picture that you see above.

Batteries had leaked in it. Whenever batteries leak in a piece of equipment, they ruin it, right?

Well, it's true that the equipment has had its life shortened. Contacts that have had corrosive chemicals on them will eventually corrode again, even if you do a good job of cleaning them up. However, it may take years for this to happen, and your gadget may give you many years of good service before any further problems arise.

The white crust that comes out of alkaline or rechargeable batteries is mostly potassium carbonate, which is is not highly toxic, although you should wash your hands after any contact with it, especially because there may be some potassium hydroxide mixed in.

Most "contact cleaner" solutions, including pure alcohol, do not dissolve potassium carbonate. Water does, but water is not good for electrical equipment — it takes too long to dry. So I use rubbing alcohol, which is 70% alcohol and 30% water.

Do not drench electronic parts with any liquid unless you have no other choice. The way I clean up battery crust is first of all to remove it by poking with toothpicks, pins and needles, and whatever else will dislodge it. (A dental pick is handy; pretend you're a dental hygienist getting tartar off teeth.) Canned compressed air helps get the crumbs out of the way once you've loosened them. (Protect your eyes!) Rubbing alcohol softens the crust nicely — let a drop of alcohol soak into the crust and stay there a few minutes, then use a pick on it. An old toothbrush also comes in handy. Use canned compressed air again at the end of the procedure, to remove moisture, and then let the equipment dry before trying to use it.

It is often neither possible nor necessary to remove every trace of residue; what's important is that the metal battery terminals need to be clean and make good contact. Plastic and metal surfaces will often continue to look corroded after they're clean because the surface has been roughened.

With the Coolpix 990, fortunately, almost all the crust was on the battery-compartment door, which I could wash (carefully, with a small squirt bottle) without getting liquid inside the camera. There was some crust deeper inside the battery compartment, but I got it out with a pick and a piece of moist tissue paper.

Then I used a Dremel tool with a rotating wire brush to polish up the metal contacts. They didn't look as good as new, but they were clean where it mattered.

Metal needs to be protected from further corrosion by adding a thin coating of oil. Sliding plastic parts need lubricating. You can do both of these with silicone oil (Armor All and similar products), applied very carefully with a toothpick or rag. If you don't have silicone oil, mineral oil will do. Other oils designed for lubrication often have additives that aren't good for plastic.

For now, the Coolpix 990 works. It may need further contact cleaning later — or it may not. In 1987 I bought a camera flash for 25 cents because batteries had leaked in it and the store considered it unsalable. I cleaned it up inside, and as far as I know, it still works.



Interesting free circuit simulation software

An interesting new circuit simulation software package has become available since the last time I looked (admittedly, that was five years ago!).

It's TINA-TI, from Texas Instruments, and the price is right: free.

As I've remarked about astronomy software, the overwhelming advantage of free software is that I don't have to buy multiple copies for multiple computers. Back when I had only one PC, I was more willing to spend $200 for a good piece of software for it. Nowadays I want to put everything on the desktop machine and two laptops, or maybe more, and I don't want to pay triple prices!

TINA-TI is a cut-down version of TINA, a commercial product, to which you can upgrade for a few hundred dollars (depending on options). But TINA-TI is quite usable by itself. It includes a good selection of components (including common ones such as NE555, TLC555, IRF501) and can import SPICE netlists. Essentially, it uses the same device models and computation engine as all the other circuit simulators. In a brief trial, I found it very easy to use.

The license terms for TINA-TI are a little quirky. You supposedly get a one-computer license, but it's free, and there's nothing to prevent you from downloading more than one copy. More curiously, I had to attest that I am not a student or educator. (Thank goodness I'm retired!) They don't want people outfitting student labs with free copies of TINA-TI.

Of course, LTSPICE and Multisim are still out there. Multisim is hard to track down — the web site was actually down yesterday — and is expensive. It is facing serious competition from freeware.

[Addendum:] A correspondent points out that I need to explain what on earth this is all about. This is software that engineers use to design electronic circuits. Traditionally, the way to test any circuit design is to build a prototype. But a good computer simulation — using the computer to calculate how the circuit will behave — is also helpful. It's quicker; you don't actually have to possess the parts; and if you make a mistake, nothing burns out or catches fire. Circuit simulation software came into use in the 1970s when engineers started designing integrated circuits that couldn't be prototyped in advance. Now it's used for discrete-component circuits, too.


Zuiko Moon

I'll get back to the Deerlick pictures soon, but first, here's a picture of the moon taken with the huge Olympus Zuiko 600-mm f/6.5 telephoto lens that I picked up at the hamfest. Single exposure with a Canon 60Da in "silent shooting" mode, vibrationless, better than any film SLR ever could be. This was taken at f/11 and postprocessed with RegiStax and Photoshop.


Quantitative battery charging and testing

I don't know if you have as many NiMH AA and AAA cells as we do. We use them in the cameras, the cell phones, a radio... and they wear out. They gradually lose capacity and eventually won't take a charge at all. We usually use them in sets of four and don't know which one of the four has worn out. A voltmeter will tell us, of course, at least roughly.

Enter the PowerEx Wizard One. This device charges and tests NiCd and NiMH cells in several different ways. Straight charging is easy, but the most useful mode is "refresh and analyze" — that is, top up the charge, discharge the cell while measuring its capacity, and charge it up again. This takes about 24 hours, and at the end, you get a reading of the measured capacity in milliamp-hours. It may be less than the rated capacity because you may be testing at a different discharge current than the manufacturer did, but it will tell you whether the battery has lost capacity and, most important, whether the four in a set are alike.

Each cell is handled separately, so one odd cell in a set won't harm or affect the others. Separately discharging and cycling the cells in a set will often make them match each other again, when they had begun to drift apart because charging them in series, the way other equipment often does, tends to magnify small differences between cells.

Highly recommended.

[Addendum:] If you put in a battery that hasn't been used for a while and choose "refresh and analyze," the display may say HIGH (meaning high resistance — the battery isn't taking a charge at the expected rate). Charge it (in "break in" mode) first.

Also, the default charge and discharge rates (1000 mA and 500 mA respectively) are suitable for high-capacity AA cells (1500 mAH and higher), but you should cut them in half for AAA cells and older-style AA cells.

[Further addendum:] This charger will often read HIGH and shut down, or simply turn itself off, when presented with a battery whose internal resistance is more than 0.5 ohm. This is a safety mechanism to avoid charging batteries that aren't NiMH. It also rejects older, deteriorated NiMH batteries, even those that seem to be taking a charge in a more primitive type of charger. The logic is apparently similar to what is described in this Texas Instruments presentation.

If you have a laboratory power supply, you can check the resistance of an NiMH cell as follows. Set the power supply to at least 5 volts with a current limit of 500 mA. Watch the voltage as you connect it across the cell. Within a few seconds, it should drop down to 1.6 V or a little less. If it stays in the 1.7-volt range or higher, the cell has developed high internal resistance.


And digital too: my new Tektronix 2014B

The other important addition to my workbench — made this very day, November 7 — is a digital oscilloscope. Unlike an analog one, a digital oscilloscope can record a transient (one-time) waveform and store it. It can also do computations on the data, including Fourier transforms (turning a waveform into a spectrum). And it can save its display onto a USB flash drive.

This one was an eBay bargain and I'm the fourth (I think) owner, but the first one actually planning to use it! It arrived in its original packaging and had only been powered on a few times, according to the internal log.

You might guess I'm finally finding time to get back into electronics, and you'd be right.

By the way, for a while I had a TDS 220 digital oscilloscope on my workbench, but it was technically on loan to the University, not to me, and has been returned to them now that I'm retired. So this instrument is not a totally new world for me, but it does have some features the other one didn't. And it's more colorful; they even provided little plastic pieces to snap onto the probes to match the colors of the traces and the knobs.


Tektronix 2245A tour

A while back I thanked our church friend Raynette Noles for giving me a Tektronix 2245A oscilloscope that she had inherited. Today I want to say a little more about it — partly because I've just finished figuring out some of its features myself!

It is an analog oscilloscope with some digital measuring circuitry added. (For the wider audience I should add that an oscilloscope draws a graph of voltage versus time. It is an instrument for investigating electrical signals of all kinds; you will see them in laboratories and repair shops.)

Because it's analog, it relies on a recurrent waveform. It doesn't record or store the wave that it's displaying. To stay on the screen, the wave has to be doing the same thing, over and over, and the oscilloscope synchronizes to it and keeps regenerating the display.

The good thing about analog oscilloscopes is that nothing weird can happen to the input signal. If it gets distorted, it will get distorted in a predictable way. Strange digital sampling effects will not happen.

The 2245A has two modes, A and B. In A mode, it is simply a four-trace oscilloscope:

Channels 3 and 4 have a limited range of input amplitudes — they're mainly for logic signals, although here you see that they are fully analog, just like the others.

The interesting part is that there are cursors for measuring voltage, frequency, and time. Here you see them measuring frequency. They have to be put in place by turning dials, and then they tell you the voltage or time difference between the two points where they intersect the wave.

Then there's B mode. In B mode, you see the same waveform as in A mode, but you only see part of it, magnified horizontally, and you can choose what part to look at.

B mode by itself is less useful than alternating A and B mode, which you see here:

The upper trace is the whole waveform, with part of it highlighted, showing what's magnified in the lower trace. Obviously, this would be more helpful with a more complicated waveform — and most waveforms are indeed a good bit more complicated than this one.


California Nebula

Here's the California Nebula, so called because of its shape. It's a gas cloud in the constellation Perseus. Elsewhere in the picture you see a bright cloud of stars and two dark nebulae (dust clouds in interstellar space). North is to the upper right.

This is the first picture that I've processed from my trip to Deerlick on Sunday, November 3. Stack of sixteen 1-minute exposures with a Canon 60Da (at ISO 3200) and Sigma 105-mm f/2.8 lens on an iOptron SkyTracker, corrected with dark frames, flat fields, and flat darks using DeepSkyStacker. Because DeepSkyStacker was used in "sigma clip" mode to reject deviant pixels, the computer deftly edited out the effects of poor tracking in a couple of frames, and even an airplane that flew through the field.

I did the postprocessing with PixInsight — this one hasn't been touched with Photoshop. Although people complain about its "steep learning curve," I think PixInsight is as easy to learn as Photoshop, if not easier. The secret to both of them is that there are hundreds of tools, most of which you're not going to use.



Sunspots on November 3. Mostly, this is proof that my new Thousand Oaks solar filter works well. Celestron 5, stack of three 1/2000-second exposures postprocessed with RegiStax and Photoshop.

Short notes

There's a lot going on here... I went to Deerlick on November 3 and took quite a few good astrophotos, which you'll eventually see here. I'm also getting my electronics workshop back into action after some months of neglect... more about that soon.

And although I don't often write about politics, I do want to refer you to this. Besides the expected economic feasibility problems with Obamacare, and the unexpectedly inept implementation of the web site, we also have an issue with false claims or, at best, culpable ignorance. "If you like your present insurance you can keep it" — says who? Regardless of whether it's conservative or liberal, this is not competent, honest government.

I wish people (especially Congress) were thinking about making urgent changes and corrections rather than just demanding total repeal or nothing.

Has anybody noticed that the quality of the U.S. government has fallen in recent years? Apart from questions about what policies they want to implement, they have fallen down in practical ability to make anything run smoothly.



Today (Nov. 2) I went to the Lawrenceville (Stone Mountain) Hamfest, which is primarily a ham radio swap meet, for the first time since 2009.

I scored big. The items of most interest to me are the offbeat ones — not common radio or computer gear, but unusual laboratory items and the like. What I ended up with was an Olympus Zuiko 600-mm f/6.5 telephoto lens in a custom-fitted carrying case, with an OM-2 camera body. For $40. Probably resalable for $800 immediately — it is so rare that KEH doesn't have one in stock — but I plan to use it for astrophotography (on a Canon DSLR body with an adapter).

That, in turn, will take a while, because I do not yet have an equatorial mount capable of carrying it. (It's essentially a 4-inch refracting telescope with a 6-element multicoated optical system.) But I can use it on a fixed tripod for full-face shots of the moon, and I can test it on star trails (and plan to do so right away).

Unexpectedly nice feature of this lens: The stiffness of the rack-and-pinion focuser can be adjusted by the user, by turning the knobs in opposite directions. (Turning them in the same direction changes the focus.)

I will test the OM-2 camera body later. It is a pro-grade camera and I don't see any obvious problems, although I haven't opened it up to look for crumbling foam or the like, nor have I put batteries in it.

It is a close relative to the only camera body I came close to wearing out. I used an OM-2S incessantly from 1985 to 1998 and it looks visibly worn, although when last used, it was still working fine.



Motorola 3360 DSL modem — "Internet" LED stays dark

If you are an AT&T customer using a Motorola 3360 DSL modem, and you've connected it to a router, and the router is in charge of logging into your AT&T account, then your Internet connection will work fine but the "Internet" LED will remain dark and not light up green.

Contrary to all documentation, this is apparently perfectly normal. Now you know.

We replaced our 5-year-old Westell modem, which had become slightly unreliable. No settings has to be made on the Motorola — we just plugged it in, powered it up, power-cycled the router, and gave it a few minutes to find the connection.

[Update:] The "Internet" light only blinks green when data packets are being sent or received from the Internet. Now you know.

To set up this modem for use with a router, where the router stores your DSL username and password, do the following:

(1) Factory-reset the modem per instructions. (With power on, hold down the reset button for several seconds, then let the modem power up.)

(2) Connect the modem directly to the Ethernet port of a PC. For now, leave your router unused.

(3) In the advanced menu, choose "PPP location" and tell the modem that you are using it in bridged mode, i.e., the router, upstream from it, will take care of logging into DSL.

(4) Save settings.

(5) Connect the modem to the "Internet" connector on your router, and connect your PC to the router in the usual way. From there, do the setup on the router if you have not already done so.


"For all the saints..."

I wish all of you a blessed All Saints' Day, the day we Christians honor our great predecessors in the faith.

Reinventing mortgages

Five years ago, our nation was brought to its knees by a bad mortgage underwriting system. Today, I'm involved in reinventing it and fixing the problems.

I work with Formfree Holdings, Inc., which has received a major award from Mortgage Technology magazine. A token of good things to come...

Short notes

Where's the astrophotography? Coming soon, probably tomorrow. I've gotten busy with real work (which is good).

Yesterday morning (October 31) I was at a business meeting and was the only one wearing a tie. Well, it was Halloween...

If what you are looking for is not here, please look at previous months.