Day: November 24, 2020

Eulogy To Arecibo: With Demise Of A Unique Scientific Facility, Who Will Carry The Torch?

November 24, 2020 by 50 Comments

Few telescopes will get an emotional response from the general public when it is ultimately announced that they will be decommissioned. In the case of the Arecibo Observatory in Arecibo, Puerto Rico, the past months has seen not only astronomers but also countless people across the world wait with bated breath after initial reports of damage to the radio telescope’s gigantic dish.

When the National Science Foundation announced that they would be decommissioning the telescope, there was an understandable outpouring of grief and shock. Not only is Arecibo a landmark in Puerto Rico, it is the telescope from iconic movies such as GoldenEye (1995) and Contact (1997). Its data fed public programs such as the Seti@Home and Einstein@Home projects.

Was Arecibo’s demise truly unavoidable, and what does this mean for the scientific community?

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Bet You Didn’t Know Arduinos Are Psychic

November 24, 2020 by 3 Comments

Are you running out of ways to entertain yourself and your family? If you’ve read all the books and watched all the movies, it might be time to explore the psychic abilities of silicon. [Hari Wiguna] has just the trick to keep them guessing for a good long time.

This trick doesn’t take much, just a couple of Arduinos, some momentary buttons, a number pad, and a large helping of math. As you can see in the demo after the break, there is nothing connecting the two, not even 802.11(n). On the randomizer Arduino, [Hari] generates random numbers with the push of a button until the audience sees one they like. Then [Hari] locks in the number with the other button.

What happens next is key: the randomizer generates another random number, but uses it as a hint to set a sentinel digit. The randomizer Arduino subtracts the larger of the two digits in the number from nine and stores the result as the flag. When the next number comes up that has the flag digit in the correct place, the number after that will be the random number chosen at the beginning.

The psychic Arduino’s secret is that it knows the first guess it receives is special. It does the same sentinel digit math as the randomizer, so when the guesser enters the guess with the sentinel digit, it knows the next number entered is the winner. Clear as mud? Check out the second video below where [Hari] explains the trick, a new take on a magic classic.

Looking for a more exciting way to generate random numbers? Try using fish tanks, lava lamps, or muons from outer space.

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Trashed Tablet Lives Again Thanks To New Charger IC

November 24, 2020 by 12 Comments

Have you ever pulled a piece of electronics from the trash that looked like nothing was wrong with it, only to take it home and find out it really is dead? Since you’re reading Hackaday, we already know the answer. Trash picking is an honored hacker tradition, and we all know it’s a gamble every time you pull something from the curb. But when the Samsung Galaxy Tab S that [Everett] pulled from the e-waste bin wouldn’t take a charge, he decided to crack it open and see if it was really beyond repair.

The first step was using a USB power meter to see if the tablet was actually pulling any current when plugged in. With just 10 mA on the line, [Everett] knew the device wasn’t even attempting to charge itself. So his next step was to pull the battery and charge it from a bench supply. This got the tablet to wake up, and as far as he could tell, everything else worked as expected. It seemed like the only issue was a blown charging circuit.

Where we’re going, we don’t need ribbon cables.

Now at this point, [Everett] could have just gone online and bought a new motherboard for the tablet and called it a day. But where’s the fun in that? Instead, he wired up a simple charging circuit using a TP4056 IC on a scrap of flexible PCB and mounted it to a square of Kapton tape. He then used 34 AWG magnet wire to connect it between the tablet’s USB port and the battery, bypassing the tablet’s electronics entirely.

The fix worked, but there was a slight problem. Since the TP4056 only goes up to 4.2 V and the battery maxes out at 4.35 V, [Everett] says his hacked charger can only bring the tablet up to 92% capacity according to Android. But considering the alternative, we think its more than a worthy trade-off.

It’s easy to dismiss tablets as largely disposable devices, but this isn’t the first time we’ve seen somebody save one with little more than solder and patience. Of course, what you do with that old tablet once you get it fired back up is another story entirely.