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Comment: A modern drawback (Score 1) 105

by bjs555 (#45173599) Attached to: Crossing the Divide From Software Dev To Hardware Dev

I love hardware. Built a 6800 machine on solderless breadboards quite a few years back. Kind of a dumb thing to do durability wise, but it was quick and easy. That brings me to my point. Many new devices these days are only available as surface mount devices. Have you ever tried to solder one of those bad boys into a circuit? The Arduino and its ilk are great but shields and stuff are basically pre-built and component level design is becoming a lost art. Well, I suppose you could say that the advent of ICs turned discrete transistor design into a dying art to an extent. Of course, things that can be done today are magical compared to 20 years ago. Ch-ch-ch-changes.

Does anyone know of an inexpensive and easy way to work with surface mount devices? Prototyping SMT boards are available from Schmartboard and others but they sure aren't inexpensive.

Comment: Re:97% of money is debt - owed to banks (Score 1) 387

by bjs555 (#44879571) Attached to: True Size of the Shadow Banking System Revealed (Spoiler: Humongous)

What if you look at it like this:

An ISP signs up customers assuming that they will not all be using their full bandwidth at the same time. So they sign up, say, 9 times more customers than they have actual bandwidth to support. Have they created bandwidth out of nowhere? If so, it doesn't seem to hurt the customers in most cases and even helps them by making their bills lower than they would have been otherwise.

Isn't this something like fractional reserve banking? Isn't the debt you're talking about something like the bandwidth from nowhere above? Maybe I'm wrong. I'm trying to get a better understanding of how banking works.

Fractional reserve banking isn't the only way to set up a banking system. For instance, there could be a 100% reserve banking system where a bank could only loan money equal to assets it holds like savings accounts and certificates of deposit. I'm not sure if that would be better.

Comment: Re:Simple comparison (Score 1) 329

by bjs555 (#44214203) Attached to: Ask Slashdot: Best Way To Store Data In Hard Copy?

How about writing the information in pencil on high quality paper? I understand that the second page of the Nicolay copy of Lincoln's Gettysburg Address that was written in pencil in 1863 (reference: http://www.loc.gov/loc/lcib/9503/gettysburg.html) is very readable to this day (image: http://myloc.gov/Exhibitions/gettysburgaddress/exhibitionitems/ExhibitObjects/NicolayCopy.aspx).

Comment: Re:PV is more practical (Score 1) 170

by bjs555 (#44175051) Attached to: Google Science Fair Finalist Invents Peltier-Powered Flashlight

But it is solar powered. The sun shines on plants. The human eats plants (or, more indirectly, animals) to generate heat to power the flashlight. Of course, there are a lot of losses along the way so there isn't much energy left to power the LED.

Congrats to her for coming up with an interesting, if impractical, science project. There's a link in the article to a video of her describing her project and it shows that she considered how much power is available from a Seebeck/Peltier device, how much is needed to power an LED, and what voltage is needed to overcome the forward LED drop.

As an emergency power source, it might be better to mount the one surface of a Peltier device on a metal bar and heat the other end of the bar in the flame of a gas stove or a barbeque grill which would still work during a power outage. An enhanced temperature difference across the Peltier device could be achieved with a heat sink on the surface opposite the one touching the hot metal bar. Power from the device could be used to charge a battery for the flashlight. Or, instead of a flashlight, an LED on a stick might serve as an electronic candle for use during an extended power outage or for camping. The battery of the electronic candle could be charged using a stove, grill, or campfire during the daytime and then provide some light at night.

The project was likely a good learning experience for her. In the comments below the video, someone mentions that both her parents are engineers. I don't know if that's true but, if so, who can claim that we don't all stand on the shoulders of giants? She just happened to be closer to some shoulders than many of us.

Comment: Re:Wow... (Score 1) 491

by bjs555 (#43733027) Attached to: Windows Blue Is Officially Windows 8.1, Free For Existing Users

I always liked the old Turbo Pascal type interface with a menu along the top that you navigated left to right along with the arrow keys. When you got to the menu item you wanted, the down arrow key opened the menu for that item. That type of interface was popular just before Win 3.0 was released. It seemed to me that Windows interface of the time was about the same except you used the mouse instead of the arrow keys. The mouse seemed slower to me mainly because of the time needed to move my hand from the keyboard to the mouse. I suppose that kind of interface still exists in the CMOS settings screen and, to this day, I prefer it to the mouse.

Comment: Re:dub in the "a" (Score 5, Interesting) 149

by bjs555 (#42431239) Attached to: Origin of Neil Armstrong's 'One Small Step' Line Revealed

Until about 10 years ago I remember hearing all broadcasts of Armstrong's quote with a definite crackling "a" before the word "man". Then the crackling "a" disappeared. It seems to me someone decided the audio sounded better without the crackling sound, edited it out, and threw away the original. Thus history was changed. It's disturbing.

Comment: Re:Desulfate lead acid batteries instead (Score 1) 198

by bjs555 (#42023121) Attached to: Old Electric-Car Batteries Put Into Service For Home Energy Storage

Maybe. I haven't tried it myself. But if you read the comments below the article you'll see that people who have nothing to sell say pulse delulfators have worked for them on batteries that won't hold a charge. People on other sites say the same thing. The stuff about matching the natural frequency of the battery sure sounds like BS but maybe the need for high frequency has something to do with the size of the sulphate crystals. Or maybe just charging at high voltage over and over at the 555 timer rate breaks up the sulphate deposits. I agree that there's a lot of BS around and it annoys me too but this seems to be in a gray area.

Comment: Re:Desulfate lead acid batteries instead (Score 1) 198

by bjs555 (#42017213) Attached to: Old Electric-Car Batteries Put Into Service For Home Energy Storage

Streetlight, you're correct in pointing out that battery failure can occur by lead shedding causing a short or open circuit. But that's only one failure mode. Sulfation occurs when a lead acid battery is discharged too deeply. That can occur by self discharge when a battery is left to stand for a long time (10 months or so) without recharging. Here's some info:
http://batteryuniversity.com/learn/article/sulfation_and_how_to_prevent_it
The comments at the bottom of the link are interesting and include some real world results. Seems there is a bit of snake oil salesmanship in the battery additive/reconditioner industry but the pulse desulfators have been around for a while and do seem to work.

Comment: Desulfate lead acid batteries instead (Score 4, Interesting) 198

by bjs555 (#42012465) Attached to: Old Electric-Car Batteries Put Into Service For Home Energy Storage

The FA talks about Li-ion batteries but I've read about people buying dead car batteries real cheap and bringing them back to life by desulfating them with a simple circuit based on a 555 timer. The idea is to pulse the battery at its resonant frequency of about 4 MHz with high voltage pulses to break up the lead sulfate crystals that often cause a battery to fail. Car batteries might be a cheaper alternative to Li-ion batteries for a home system. Here's a link to the circuit:
http://www.reuk.co.uk/Battery-Desulfation.htm

Comment: Re:Use compressed air instead! (Score 1) 198

by bjs555 (#42012397) Attached to: Old Electric-Car Batteries Put Into Service For Home Energy Storage

You need to pump a lot of water to store the equivalent energy of a 50 Amp hr car battery. In fact, you'd need to pump all the water from a typical size swimming pool up 8 feet. And for a 10 KWhr system you'd need at least 16 batteries or 16 swimming pools. That suggests a new unit of energy - the swimming pool = at a height of 8 feet, the energy storage capacity of one car battery. Here are my calculations:

A typical car battery is rated at 50 Amp hr.
To get energy, multiply by battery voltage of 12.5 V.
Max energy stored in battery = 50 Amp hr * 12.5 V = 625 Watt hr.
Battery could supply 625 Watts for one hour or 62.5 Watts for 10 hours.

1 Watt hr = 3600 Joules
1 Joule = 0.7376 ft lb

625 Watt hr * 3600 Joules / Watt hr = 2,250,000 Joules

2,250,000 Joules * 0.7376 ft lb / Joule = 1,659,600 ft lb

1,659,600 ft lb * 1 ton / 2000 lb = 830 ft tons
Must lift 1 ton 830 feet or 10 tons 83 feet to store the same energy as a car battery.

1 gallon of water weighs 8.34 lb.
24,000 gal of water weighs 100 tons.
An average swimming pool holds 20,000 gal of water or about 100 tons of water.
Must pump all the water in a swimming pool up 8 ft to store the same energy as a car battery.

The test of intelligent tinkering is to save all the parts. -- Aldo Leopold

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