Flexible Phototransistor Will Make Everything Subtly Better In The Future

February 13, 2016 by Gerrit Coetzee 23 Comments

University of Wisconsin-Madison is doing some really cool stuff with phototransistors. This is one of those developments that will subtly improve all our devices. Phototransistors are ubiquitous in our lives. It’s near impossible to walk anywhere without one collecting some of your photons.

The first obvious advantage of a flexible grid of phototransistors is the ability to fit the sensor array to any desired shape. For example, in a digital camera the optics are designed to focus a “round” picture on a flat sensor. If we had a curved surface, we could capture more light without having to choose between discarding light, compensating with software, or suffering the various optical distortions.

Another advantage of the University’s new manufacturing approach is the “flip-transfer” construction method they came up with. They propound that their method produces a vastly more sensitive device. The sensing silicon sits on the front of the assembly without any obstructing material in front; also the metal substrate it was built on before flipping is reflective; also increasing the sensitivity.

All in all very cool, and we can’t wait for phone cameras, with super flat lenses, infinite focus, have no low light capture issues, and all the other cool stuff coming out of the labs these days.

Deaccelerating The Apple IIc Plus

February 13, 2016 by Brian Benchoff 40 Comments

The Apple IIc Plus is arguably – very arguably from my experience – the best Apple II computer ever made. It’s portable, faster than the IIe, had a much higher capacity built-in drive, and since the Plus could run at 4MHz, it was faster than the strange eight or sixteen bit Apple IIGS. Recently, [Quinn] has been fascinated with the IIc Plus, and has gone so far as to build a custom gamepad and turn the IIc Plus into a laptop. Now, she’s turned her attention to the few things Apple got wrong with the Apple IIc Plus – the startup beep and defaulting to 4MHz on every boot instead of Apple II’s standard 1MHz that’s used in the Apple II, II Plus, IIe, and IIc non-Plus.

The original Apple II is surprisingly primitive. Apart from writing a loop of NOPs and counting cycles, there’s no way to keep time. There is no clock, no timer, no tick counters, and no interrupts. If you’re writing a game for the Apple II that depends on precise timing, the best you’ll be able to manage is a delay loop. This worked for a time, until the Apple IIc Plus was released with a default clock of 4MHz. It was a great idea for AppleWorks and other productivity apps, but [Quinn] is doing retrocomputing, and that means games. Booting the Apple IIc Plus into its 1MHz mode means turning it on and holding escape while resetting the computer every time. It’s very annoying, but a mod to make the IIc Plus run at 1MHz by default would turn her into one of the most accomplished currently active Apple II developers.

The process of booting into the IIc Plus’ 1MHz mode requires holding down escape while restarting the computer. This should tell you something: it’s not a hardware switch that changes speed. It’s in the ROM, and that means diving into the Technical Reference Manual, looking at the listings in the ROM monitor, and figuring out how everything works.

The IIc Plus ROM is incredibly complex – it’s 32k of hand assembled code with jump tables bouncing everywhere. After a ton of research, [Quinn] successfully reverse engineered the ‘slow down if the ESC key is pressed’ routine, allowing her to boot the machine at 1MHz by default, and 4MHz if there’s a soft reset with the option key pressed. Everything works great, and [Quinn] has the video to prove it

This isn’t [Quinn]’s first attempt at hacking the lowest levels of the Apple IIc Plus ROM. Because the IIc Plus ran at 4MHz by default, the startup beep was so very wrong. She fixed that, and with two very useful patches under her belt, she burned a few new chips with her ROM patches. In total, there’s only a few dozen bytes of hers in the new 32k ROM, but that’s enough to make her one of the top current firmware developers for the Apple II platform.

Brushed DC Servo Drive

February 13, 2016 by Anool Mahidharia 37 Comments

Brushless DC motors, and their associated drive electronics, tend to be expensive and complicated. [Ottoragam] was looking for a cheaper alternative and built this Brushed DC motor servo controller and the results look pretty promising. Check out the video after the break.

He needed a low cost, closed loop drive for his home-brew CNC. The servo drive is able to supply a brushed DC motor with up to 7 A continuous current at up to 36 V which works out to about 250 W or 1/3 HP. It does closed loop control with feedback from a quadrature encoder. The drive accepts simple STEP and DIRECTION signals making it easy to interface with micro controllers and use it as a replacement for stepper motors in positioning applications. All of the control is handled by an ATmega328P. It takes the input signals and encoder data, does PID control, and drives the motor via the DRV8701 full bridge MOSFET driver. There’s also some error detection for motor over-current and driver under-voltage. Four IRFH7545 MOSFETs in H-bridge configuration form the output power stage.

This is still work in progress, and [Ottoragam] has a few features pending in his wish list. The important ones include adding a serial interface to make it easy to adjust the PID parameters and creating a GUI to make the adjustment easier. The project is Open Source and all source files available at his Github repository. The board is mostly surface mount, but the passives are all 0805, so it ought to be easy to assemble. The QFN footprint for the micro controller could be the only tricky one. [Ottoragam] would love to have some beta testers for his boards, and maybe some helpful comments to improve his design.

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Glitching Square Wave Clock Is Designed To Confuse

February 12, 2016 by Gerrit Coetzee 25 Comments

[Voja Antonic] has built a clock that tells the time in binary with square waves, and trolls the uninitiated in electronics.

The clock itself is very attractive. If you look closely you can see the circuitry backlit behind the dot LED matrix display. The whole thing is housed in a nicely folded steel case. RGB LEDs are used to good effect to highlight some additionally obfuscating circuit schematics. The workmanship is very top notch, and we would gladly host such an object on our desks.

The clock’s standard time telling mode is three sets of square waves showing the binary values for the hours, minutes, and seconds. Every now and then the clock will glitch out. The waves will distort. The colors will change. And every now and then, tantalizingly, the alpha-numeric time will show up for just a split second, before returning to those weird squiggles again.

We’ve seen a whole slew of binary clocks before. This one, for instance. But the waveform display makes us feel just that little bit more at home — it’s just like we’re sitting in front of our oscilloscope.

New Efficiency Standards For Wall Warts In The US

February 12, 2016 by Gerrit Coetzee 190 Comments

The common household wall wart is now under stricter regulation from the US Government. We can all testify to the waste heat produced by many cheap wall warts. Simply pick one at random in your house, and hold it; it will almost certainly be warm. This regulation hopes to save $300 million in wasted electricity, and reap the benefits, ecologically, of burning that much less fuel.

We don’t know what this means practically for the consumer. Will your AliExpress wall warts be turned away at the shore now? Will this increase the cost of the devices? Will it make them less safe? More safe? It’s always hard to see where new regulation will go. Also, could it help us get revenge on that knock-off laptop adapter we bought that go hot it melted a section of carpet?

However, it does look like most warts will go from a mandated 50-ish percent efficiency to 85% and up. This is a pretty big change, and some hold-out manufacturers are going to have to switch gears to newer circuit designs if they want to keep up. We’re also interested to hear the thoughts of those of you outside of the US. Is the US finally catching up, or is this something new?

Gatling Gun Shoots Arrows Out Of Coke Bottles

February 12, 2016 by James Hobson 20 Comments

[JoergSprave] has done it again. His latest, most ridiculous weapon? A Gatling gun that fires crossbow bolts, using compressed air inside coke bottles — and an electric screwdriver.

For those of you not aware, [Joerg] is our favorite eccentric German maker, a purveyor of slingshots and all things ridiculous and weaponised. He runs the SlingShot Channel on YouTube, and has graced us with things like a slingshot cannon (firing 220lb balls!), a machete slingshot for the upcoming zombie apocalypse, and more.

Each coke bottle has a quick release pneumatic air valve, with a wooden lever attached to it to make opening the valve easier and quicker. The coke bottles are pressurized separately using an air compressor, but can also be filled using a bicycle pump — he got his hands on a pump capable of putting out 300 PSI! Word of safety though — you really don’t want to use coke bottles as pressure vessels — but [Joerge] is crazy so we’ll let it slide. Continue reading “Gatling Gun Shoots Arrows Out Of Coke Bottles” →

Frickin’ Amazing Clock

February 12, 2016 by Anool Mahidharia 22 Comments

We’ve featured a lot of clock builds, but this one, as the title suggests, is frickin’ amazing. Talented art student [Kango Suzuki] built this Wooden Mechanical Clock (Google translation from Japanese) as a project while on his way to major in product design. There’s a better translation at this link. And be sure to check out the video of it in motion below the break.

[Kango]’s design brief was to do something that is “easy for humans to do, but difficult for machines”. Writing longhand fits the bill, although building the machine wasn’t easy for a human either — he needed six months just to plan the project.

The clock writes time in hours and minutes on a magnetic board. After each minute, the escapement mechanism sets in motion almost 400 wooden cogs, gears and cams. The board is tilted first to erase the old numbers, and then the new numbers are written using four stylii.

The clock doesn’t have any micro controllers, Arduinos, servos or any other electronics. The whole mechanism is powered via gravity using a set of four weights. [Kango] says his biggest challenge was getting the mechanism to write the numbers simultaneously. While he managed the geometry right, the cumulative distortion and flex in the hundreds of wooden parts caused the numbers to be distorted until he tuned around the error.

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