3D Printed Abacus iPhone 5s Case

We aren’t sure whether you know how to use the ancient calculating device, but if you just need a unique way to protect your iPhone 5/5s, the 3D printed iPhone 5s case may be suitable for you. This is an interesting form-fitting protective case that measures approx 2.4 x 5.0 x 0.5 inches, and designed for iPhone 5 and iPhone 5s.

As we can see from the images, the iPhone 5 case is shaped as an abacus along with Apple logo-like beads, and all the tiny beads can be moved smoothly and freely so you can use the protective case as a real abacus. Moreover, the iPhone 5s case is made of white nylon plastic polished to reveal a smooth matte finish in order to protect your iPhone 5/5s from bumps and scratches and provide a comfortable grip. Apart from that, all iPhone buttons and ports are accessible via custom openings.

The 3D printed abacus iPhone 5s case is priced at $24 USD. If you’re interested, jump to Shapeways official site for more details. Additionally, if you need other options you might like to check O!Coat FaaGaa iPhone 5s case and more via “iPhone 5 case” tag. [Via]

Room Recorder

My wife was working on a doctoral dissertation and needed to do some field work involving personal interviews in various settings. What would be the best way, technically speaking, to record the interviews? To pass a tape recorder or microphone back and forth seemed too awkward and clipping wired microphones to interviewees didn’t make for a particularly informal atmosphere. Radio microphones seemed overly expensive, too. After some thought, I can up with the "Room Recorder", an add-on microphone preamplifier circuit for use with a tape recorder. While I don’t make any great claim to originality for the circuit, it has produced first class results over one year of interviews and might prove useful to anyone doing similar work.

Circuit diagram:

Room Recorder Circuit Diagram

The preamplifier was plugged into a Sony Cassette-Corder (any similar device will work) by means of a long, screened microphone cable and placed in a central location in a room or on a bench. The circuit will pick up every whisper, so background noise should be considered when choosing a location. A 2-terminal electret microphone picks up the sound, which is then amplified by a TL071CN low-noise op amp. Note that the microphone’s negative terminal is connected to its case. Negative feedback is applied to the inverting input through a 10kO resistor. Increasing the value of this resistor will increase sensitivity, and vice versa. For ease of use and quietness of operation, the circuit is powered from a 9V battery. The power switch is mounted on the case. The circuit draws about 2mA and would therefore give about 10 days continuous service from a 9V alkaline battery.

Author: Thomas Scarborough - Copyright: Silicon Chip Electronics

Romo the Smartphone Robot

So you happen to be a smartphone user for the past few years already, and have more or less gotten bored of the device, so much so that you are thinking about the possibilities of a new kind of smartphone accessory which would make you a starry-eyed kid once again, with wonder written all over your face.

Perhaps there might be something out there in the ever evolving consumer market, and the $149.99 Romo the smartphone robot could very well fit your desires to a ‘T’. Romo might even end up being your new best friend if you are a social outcast, as Romo will learn and grow up with you the more time you spend with it and interact alongside. Basically, I guess you could call this the geek’s Furby, as the more you make use of him, the faster and more he will be able to learn.

Sure, he looks cute as heck – at least getting near Wall-E levels, and is controllable via any Wi-Fi enabled computer or iOS device. The Romo the smartphone robot might be the perfect fodder to help you break down walls if you are not too good with kids, and it also brings your standard video chat sessions to a totally new level. [Via]

Power Diode For Solar Power Systems

Apart from the sun, solar power systems cannot work without a reflow protection diode between the solar panel and the energy store. When current flows into the store, there is a potential drop across the diode which must be written off as a loss in energy. In the case of a Schottky diode, this is not less than 0.28 V at nominal current levels, but will rise with higher ones. It is clear that it is advantageous to keep the energy loss as small as possible and this may be achieved with external circuitry as shown in the diagram. The circuit is essentially an electronic switch consisting of a high precision operational amplifier, IC1a, a Type OP295 from Analog Devices, and a MOSFET, T1.

This arrangement has the advantages over a Schottky diode that it has a lower threshold voltage and the lost energy is not dissipated as heat so that only a small heat sink is needed. When the potential at the non-inverting input of the op amp, which is configured as a comparator, rises above that at the inverting input, the output switches to the operating voltage. The transistor then comes on, whereupon light-emitting diode LD1 lights. Diode D3 clamps the inputs of IC1a so that the peak input voltage cannot be greater than half the threshold voltage, provided the values of R3 and R4 are equal.

The op amp provides very high small-signal amplification, a small offset voltage, and consequent fast switching. The MOSFET changes from on to off state and vice versa at drain -source voltages in the microvolt range. In the quiescent state, when UDS is 0 V, the transistor is on, so that LD1 lights. The operating voltage (C–A) may be between 5 V (the minimum supply for the op amp and the input control potential, UGS, of the transistor) and 36 V (twice the zener voltage of D1). Zener diode D1 protects the MOSFET against excessive voltages (greater than ±20 V). Diode D3 and resistors R3 and R4 halve the potential across the inputs of the op amp.

This ensures that operation with reversed or open terminals is harmless. The substrate diode of the MOSFET is of no consequence since it does not become forward biased as long as the forward voltage, USD, of the transistor is held very low. The on -resistance, RSD(on), of the transistor is only 8 mΩ and the transistor can handle currents of up to 75 A. When the nominal current is 10 A, the drop across the on-resistance is 80 mV, resulting in an energy loss of 0.8W. This is low enough for a SUB type with a TO263-SMD case to be used without heat sink. When the current is 50 A, however, it is advisable to use a SUP type with a TO220 case and a heat sink since the transistor is then dissipating 12.5 W.

Even then, the voltage drop, USD = 0.32 V is significantly lower than that across a Schottky diode in the same circumstances. Moreover, owing to the high precision of IC1a, a number of transistors may be used in parallel. The circuit proper draws a current of 150 µA when only one of the op amps in the OP295 is used. An even lower current is drawn by the alternative Type MAX478 from Maxim. However, the differences between these two types are only relevant in the low current and voltage ranges. Both have rail-to-rail outputs that set the control voltage accurately even at very low operating voltages.

This is important since the switch-on resistance of MOSFETs is not constant: t drops significantly with increasing gate potentials and decreasing temperature. A experimental circuit may use an LM358 op amp and a Type BUZ10 transistors, but these components do not give the excellent results just described.

Toshiba Excite 7 Android Tablet Announced

Toshiba has announced Excite 7, its latest Android tablet. If you’re looking for a balance option between price and performance, the 7-inch tablet may be able to catch your eyes. Toshiba Excite 7 is a budget friendly and high performance Android tablet that runs on Google Android 4.2.2 Jelly Bean mobile operating system.

The Android tablet is powered by Rockchip RK3188 quad-core processor, and comes with 1GB RAM, 8GB eMMC internal storage, 7-inch capacitive 5-finger multi-touchscreen LCD display with 1024 x 600 pixels resolution, 0.3-megapixel front-facing webcam and 3-megapixel rear camera.

Moreover, other specs also include WiFi, Bluetooth 4.0, microSD card slot, stereo speakers and 14W-hours rechargeable battery for up to 8 hours of video playback. Toshiba Excite 7 Android tablet is priced at $169.99 USD. If you’re interested, jump to Toshiba official site for more details.

Flashback iPhone 5s Case

Hard-shell iPhone5 case in a throwback design that'll have you partying like it's the year 2000. Allows for full access to all ports and controls & easily snaps right on n' off.

Content care ,Plastic,Wipe clean,Imported,Size Fits iPhone 5

Cookie Shaped USB Mug Warmer

Want to comfortably enjoy your favorite coffee beside your computer? Take a look at the cookie shaped USB mug warmer, it may be able to catch your eyes. This is an interesting and practical USB mug warmer that measures 4 inches in length and 1 inch in width.

As we can see from the images, the USB mug warmer is shaped as a chocolate sandwich cookie, and features delicious details and colors. Of course, you can put it into your mouths, but using integrated USB cable you can connect the cookie shaped USB cup warmer to your computer in order to keep your favorite beverage piping hot – up to 140 degrees. Apart from that, the mug warmer is compatible with all Mac and PCs.

The cookie shaped USB mug warmer is priced at $14 USD. If you’re interested, jump to Urban Outfitters for more details.