Archive for category knowledge base

Headless Raspberry Pi B+ via Ethernet – from zero to success

R.Pi B+ BoadSo (somewhat late to the party, but anyway), I came up with a project I could use a Raspberry Pi for. Off to Amazon I went, and purchased this starter package (select the ULTIMATE kit), which I highly recommend. Everything you need, all in one place. I’m assuming you either bought this kit, or have the things you need, which I will also call out in case you’re a masochist and plan to try to assemble all this stuff by yourself.

To start, you will require the Pi B+, a storage card with NOOBS on it, a power supply, a wired USB keyboard, a wired USB mouse, an ethernet cable, a free port on your network router or network switch, an HDMI cable and an HDMI capable monitor.

No, there’s no other way. You need the monitor, keyboard and mouse. Sorry. Not my fault. Everything I listed except the network cable, keyboard, monitor and mouse is supplied in the kit I linked to just above. As well as a lot of other really cool stuff. Hint. Hint.
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Let’s talk Evidence.

One of the common aphorisms we hear in two varieties is, first form, “absence of evidence is evidence of absence”, and second form, “absence of evidence is not evidence of absence.” Either statement seems to make sense on its face; but this is because of a common misunderstanding. In truth, only one form actually works for us within the bounds of reason.
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Buitoni Toaster Pizza

Buitoni Toaster Pizza.

Buitoni Toaster Pizza

Buitoni Toaster Pizza

Seriously? Yes, seriously. These were amazing frozen little za’s you put in, heated a bit, let sit so they’d defrost all through, then put in for a final heating, and finally let sit for a minute after that, and then you could eat them. Oh, man were these amazingly good. A great sauce, excellent cheese, and the shell came out as a lightly browned, delicious crust.

You could do it wrong — over- or under-cook, not let it defrost completely, not wait that extra minute and burn the heck out of your mouth… all risks eminently worth taking.

Ever think you might like to do me a favor if it was easy? Then please go to Buitoni’s facebook page and nudge them about this. Or search Google and find the Buitoni Toaster Pizza page, join, “like” them, and say something nice to encourage them. I guarantee the odds are very high that if you love good pizza, you’d like these. It wasn’t fast food. It was something else entirely. Call it an accident, or a fortuitous event in frozen foods, but don’t write it off.

Buitoni Toaster Pizzas. Oh, man.

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Marantz MA700 troubleshooting

I have quite a few Marantz MA700′s; of the group, four of them exhibit random popping sounds of moderate energy at the speaker output with no audio input to the unit. Clearly this is a very common failure mode for the MA700.

I have opened one of the “poppers” up on the bench, and with the buffer amplifier signal cable to the power amplifier disconnected, the popping noise remains, so it’s definitely not in the audio path on the buffer amplifier board. The buffer amp is connected to the power amp via an electrolytic, so there’s no problem unplugging the buffer from the power amp.

There’s another problem with this unit, too: I see somewhat random engagement of the high power rail mode for the amp, but this is not co-incident with the clicking coming from the speaker.

When the high/low power state switches randomly, the associated relay clicks, which is audible at very low volumes, and this is obviously not the design intent. Erratic high/low power switching problems are going to be nearby QU05, very likely the electrolytic CU08, the diodes DU01 and DU02, or QU05 itself. I’d suspect CU08 first.

The main amp PCB shows evidence of excessive heating towards the front of the chassis, where the driver section is located. Unfortunately, it looks to me that the mechanical assembly is complex with regards to the main amp and attached heat sink; taking it apart looks to be quite a big deal, my vision has become very poor, and I don’t actually need the amp, so I’m just going to close up. However, at least this exonerates the buffer amp and provides a pointer as to how to troubleshoot high/low rail power issues.

If anyone locates a specific component that is responsible for the clicking and popping, I would very much appreciate hearing about it; I’m willing to hack in a replacement electrolytic from the component or solder side of the board if that’ll solve the problem. Likewise, if circumstances lead me there — if one of my working MA700′s fails and I really need to fix one of these “poppers” — I’ll post what I’ve learned.

I’ve put the service manual for the MA700 online here.

–Ben, AA7AS

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Analyzing the 2nd Amendment Correctly

rippedThe 2nd Amendment is in the news again. As I come across various news stories and blog posts like this one, I repeatedly find attempts to present an explanation of this portion of the constitution. Some of these attempts err because they use modern definitions for terms that meant something else when the amendment was written; some fail because they don’t catch on to the difference between an instruction to government and an explanation to the reader; some are outright propaganda, written to conform to a point of view without regard to any intent to get at an accurate reading.

I’ve spent quite a lot of time looking at this over the years. Although you may begin to feel as you read this that I am pro-gun, in fact I am not. What I am is pro-constitution. As you’ll see if you read this completely, the constitution provides for change, and the obvious path is, if you want change, you should make that change — properly. Please read this to the end before you decide that I’ve got a foot in the door here, for or against the “rightness” of American citizens being armed.

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Happy Thanksgiving

Today is a good day to remember the true spirit of the pilgrims. They would occasionally take a day off from shaming community members in the town square stocks and recreational witch-burning to deliver typhus-infected blankets to the native American Indians nearby, in the fond hope that they be decimated under the loving eyes of God, consequent to the long European tradition of biological warfare against those one would prefer go away. Lest you think the Pilgrim’s work ethic be implicated here, know you that from time to time, they would also organize and do their very best to commit genocide on the local Indian populations in fine traditional fashion, utilizing both sharp and blunt objects – stabbing Indians was equally as well regarded as bludgeoning. In addition, Indian men, women and children received equal consideration in this matter, so you can see that this is truly a multi-dimensional egalitarianism. This may be regarded as one of the true seeds of American fairness.

These are true facts. If this is not how you regard Thanksgiving, perhaps you should re-examine your knowledge of history. Google for UAINE and/or the Wampanoag tribe. Spend a few minutes reading up on actual pilgrim practices.

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Demolishing AI’s “needs a body” argument

robbyAmong other things, I’m extremely interested in the presently nascent field of artificial intelligence. I do some coding in the area as I find time, as well as in the area of artificial life and evolutionary software. One consequence of this is that I am often exposed to opinions and ideas from others with the same interests. Here, I’m going to take on – and take down – one of the less well thought-out ideas that are currently making the rounds; that idea that, in order to have intelligence, that device must also have a body.

Where does this idea come from, you may ask? Professor Alan Winfield, Hewlett Packard professor of electronic engineering at the University of the West of England, says “embodiment is a fundamental requirement of intelligence in general” “a disembodied intelligence doesn’t make sense.” Susan Greenfield, professor of pharmacology at Oxford University’s Lincoln College, says “My own view is that you can’t disembody the brain.”

So there’s the setup, as it were. Here’s the knockdown.

If a person is deaf, do they suddenly become unintelligent? No. If a person is deaf and blind, do they suddenly become unintelligent? No. If a person is deaf, dumb and blind, do they suddenly become unintelligent? No. If a deaf, dumb and blind person suffers a spinal injury and loses nervous system contact with the body, do they suddenly become unintelligent? No. And so it goes. Intelligence is not about the senses, and it is not about mobility, nor, in the end, is it about structure.
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Breaking things in martial arts

punchyBreaking things – boards, bricks, concrete, bones – is about the delivery of kinetic energy. I’m not just talking about the cheesy pine board breaks they have 6-year olds do at the kiddie martial arts class, either. I’m talking about serious breaks, with real bricks, concrete, and so forth.

Ke2First of all, the relevant physics terms are in the mass times the square of the velocity portion of the kinetic energy formulation. Mass and velocity are the user-controllable parameters that determine just how much kinetic energy will be delivered to the target. Let’s consider the fist.

Generally speaking, the mass is the fist, plus, if the wrist and elbow are held rigid, the mass of the two arm sections and even the shoulder; real experts can hold the shoulder rigid at the time of impact, and so a surprising amount of central body mass can be counted in the formula. From there, breathing (and yelling) techniques that give you a rigid structure through your chest and stomach musculature, and the locking of the hips and legs through the moment of contact. But once you get that far, you’re kind of stuck – because you don’t have any more mass.

Velocity, though, both counts more (because it’s squared) and is easier to boost as compared to your average other person, because we don’t really generally work at anywhere near our potential speed.
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