It Sucks to Pick Up the Pieces

Jigsaw puzzles are a fun and interactive way to spend an afternoon or twelve, depending on the piece count and your skill level. It’s exciting to find the pieces you need to complete a section or link two areas together, but if you have poor dexterity, excitement can turn to frustration when you move to pick them up. [thomasgruwez] had the disabled and otherwise fumble-fingered in mind when he created this pick and place jigsaw puzzle aid, which uses suction to pick up and transport puzzle pieces.

The suction comes from an aquarium pump running in reverse, a hack we’ve seen often which [thomasgruwez] explains in a separate Instructable. A large, inviting push button is wired in line to turn the pump on and off. An equally large and inviting momentary switch turns off the vacuum temporarily so the piece can be placed.

At the business end of this hack is the tiny suction-cupped tip from a cheap vacuum pen. To interface the pen head with the pump, [thomasgruwez] designed and printed a rigid straw to bridge the gap. With utility already in mind, [thomasgruwez] also designed a ring that can be bolted to the straw to house a steadying finger of your choice, like the pinkie hook on a pair of barbers’ shears.

Our favorite part of this hack has to be the optional accessory—a tiny platform for quickly flipping pieces without cutting the vacuum. Check it out after the break.

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Simple One-Chip Regenerative Receiver

Crystal radios may be the simplest kind to make, but regenerative receivers are more practical and only a little more complicated. A recent design by [Selenium] is super simple because it uses a single LM386 audio amplifier IC.

You might be surprised that you can convert an audio amplifier to a receiver using just a handful of components (a variable capacitor, a coil, a handful of capacitors, and a speaker). However, [Selenium] realized he could subvert the gain and bypass pins to cause regeneration and wound up with a very simple receiver.

If you haven’t looked at regenerative receivers before, the principle is simple (and dates back to 1912). An oscillator is an amplifier that gets (theoretically) an infinite amount of gain at one particular frequency. A regenerative receiver is just an amplifier that is almost (but not quite) at the point of oscillation. This gives it very high frequency-specific gain and a measure of selectivity. You can also nudge the receiver just into oscillation to receive CW or SSB signals.

[Selenium] built his prototype on an old receiver chassis because it had the IC and the variable capacitor already in place. However, others have built successful copies on breadboards ([Austin Heller] created several good looking breadboard versions) and on PCB material. [Selenium] also released some other unique LM386-based designs that use more parts (and, probably, have better performance). Looks like a simple way to build a practical receiver.

Robot Control Ties RC Receiver to Motor Controller

[Andrey Nechypurenko] has posted the second part of his robotics ground vehicle design guide. In his first post [Andrey] detailed the mechanical design decisions he faced. [Andrey] now begins covering the electrical components, starting with manual control using a standard radio control system. To accomplish this an RC system was used with an MD22 h-bridge driver and a picoUPS.

The MD22 is a neat motor control board which can take the PWM signals from the radio controller and use this to drive the DC motors. Optionally it can also use an I2C interface, giving a nice migration path to integrate with a microcontroller. Until that happens this can’t really be called a robot — its more of an RC vehicle. But the iterative design and build process he’s using is a good one!

The picoUPS provides on-board battery charging. Due to its UPS heritage it also allows the vehicle to be powered from an external supply, which has proved useful during development. Finally, a 5v regulator was required to supply the on-board digital logic. [Andrey] wanted a quick drop in solution with a budget large enough to allow for future expansion and went with the Pololu D15V35F5S3 which can supply 3.5 amps in a small and easy to use module.

After breadboarding the system [Andrey] fabricated a PCB to integrate all the components. The next step is to add sensors and and embedded computer to the platform.

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Hackaday Prize Entry: It’s Like Apple Pay, But For Receipts

There’s Apple Pay, Samsung Pay, Google Wallet, and a host of other ways to pay for stuff with your phone. What about receipts, though? Do you really need to carry around little bits of paper to prove to incredulous friends you have, indeed, bought a donut? The proof is back home, in the file. Under D, for donut.

[Hisham] is working on a very interesting system for the Hackaday Prize. It’s effectively the the opposite side of every point of sale transaction that Apple Pay, Samsung Pay, and Google Wallet are working on. Instead of handling payment, [Hisham]’s Aelph handles receipts.

[Hisham]’s project is hardware, with a small device that plugs into a point of sale terminal. This device transmits a receipt to the Aleph app (or a third party app), and uploads a PDF copy of the receipt to a server. Other than a small hardware box, there’s no additional software required for a POS terminal. For retailers, it’s as easy as plugging in a box, and for consumers, it’s as easy as downloading an app.

The hardware was prototyped on a TI LaunchPad featuring a TIVA C microcontroller. This, along with the NFC eval kit give Aleph more than enough power to connect to a company LAN and spit out a few PDFs. You can check out one of [Hisham]’s demo videos below.

There are a lot of benefits to a electronic receipts; if you ever need a receipt, odds are you’ll scan it anyway – a dead tree receipt is just inefficient. There’s also some nasty chemicals in thermal receipt paper. You only need to Google ‘BPA receipt’ for that evidence. Either way, it’s a great idea, and we long for the day that our wallets aren’t stuffed to Costanzaesque proportions, and a time where we won’t need a scanner to complete an expense report.

The 2015 Hackaday Prize is sponsored by:

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3D Miniature Chess Pieces Made With A Laser Cutter

When you think of laser cutters, you generally don’t think of 3d parts. Well, at least not without using something like glue, nuts and bolts, or tabs and slots to hold multiple parts together. [Steve Kranz] shows you how to make these very tiny 3D chess pieces by making 2 passes at right angles to thick acrylic. The first pass cuts one side’s profile, then the part is rotated 90 degrees and a second pass is cut, giving the part more of a “real” 3D look, rather than something cut out of a flat sheet. If you’re having a hard time imagining how it works, his pictures do a great job of explaining the process. He even added some engraving to give the chess pieces for a selective frosted look. We think it’s a cool idea, and well executed too!

But that got us to thinking (always dangerous) that we’ve seen rotary attachments for laser cutters, but they are mainly for etching cylindrical objects like champagne flutes and beer bottle. What if you added a rotating “3rd” axis to a laser cutter that could hold a block of material and rotate it while being cut? (Much like a traditional 4th Axis on a CNC machine). Would the material also need to be raised and lowered to keep the laser focused? Surely software that is aimed at 3D CNC would be needed, something like Mach3 perhaps. A quick Google search show that there are some industrial machines that more-or-less do 3D laser cutting, but if you, or someone you know of, has attached a 3rd axis to a desktop laser, let us know in the comments, we would love to see it.

(via Adafruit)

EDF Removes Hill Necessity For Snowboarding

Getting stuck on a flat portion of a trail while snowboarding is a major buzz kill. You can either hop yourself to the nearest slight downhill or unstrap your board and take a walk. Neither option is fun. [Jude] was tired of getting stuck on the flats so he strapped an electric ducted fan to the back of his snowboard.

The powerplant is an Electric Ducted Fan (EDF) intended for RC Aircraft. It is supported on the snowboard by a 3D printed mount. [Jude] made his mount design available for anyone interested in following his lead. Good ole glue holds the fan to the mount and the mount to the snowboard.

The battery is a 12S, which means it has 12 LiPo cells, 3.7 vdc each, wired in series to put out 44.4 volts. Inbetween the battery and brushless motor in the EDF is an Electronic Speed Control (ESC) that is normally used for RC vehicles. [Jude] purchased an ultra-cheap RC transmitter and receiver setup to give him one-handed wireless control of the fan’s speed. He estimates he can hit 15 mph on flat ground. If nothing else, it looks darn fun to ride!

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Simple Superheterodyne SW Receiver Harks Back Almost 100 years

Early radio receivers worked on a principle called Tuned Radio frequency (TRF), patented in 1916. They weren’t very easy to use, requiring each stage to be tuned to the same frequency (until ganged capacitors made that a bit easy). The Superheterodyne design, devised in 1918, was superior, but more expensive at that time. Cost considerations led adoption of the Superhet design to lag behind TRF until almost 1930. Since then, until quite recently, the Superhet design has been at the heart of a majority of commercial radio receivers. Direct Conversion Receivers were devised around 1930, but required elaborate phase locked loops which restricted their use in commercial receivers. The point of all this background is that the Superhet design has served very well for more than 90 years, but will soon be rendered redundant once Software defined Radio (SDR) becomes ubiquitous. Which is why this study of the simple Superheterodyne shortwave receiver deserves closer study.

[Dilshan] built this two transistor and two IF transformer based superheterodyne radio designed to receive 13m to 41m bands. The whole build is assembled on a breadboard, making it easy to teach others to experiment. [Dilshan] offers very useful insights into antenna, rod coil and IF transformer parameters. To dive in to Radio architecture, check this post on Amateur Radio. And if you would like to get a closer look at Antique Radios, check this post on Restoring Antique Radios.