Author: Al Williams

4469 Articles

Key-tar Lets You Jam At The Hackerspace

November 8, 2017 by 4 Comments

We’ve seen our share of stepper motors making music, but [Tanner Tech’s] key-tar takes it to a whole new level. Incorporating an acoustic drum to accentuate the stepper motor sounds and a preamp to feed a guitar amplifier, the key-tar is a fully playable instrument.

Moving the stepper via an Arduino at different speeds creates different notes. The user interface is an old PC keyboard. Apparently, [Tanner] recycled most of the parts in his model. The stepper came from an old printer and the keyboard was a dumpster rescue.

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Bionic Eye Trial Approved

November 7, 2017 by 27 Comments

Pixium Vision, a French company, has received the approval to begin in-human trials of a miniature wireless sub-retinal implant. Named PRIMA, the device may help those with advanced dry age-related macular degeneration get improvements in their eyesight. The company is in talks to also conduct trials in the United States.

The PRIMA implant is a photovoltaic chip about 2mm square and only 30 microns thick. That’s tiny, but the device has 378 electrodes. The patient uses a device that looks like a conventional pair of glasses but contains an integrated camera that sends data wirelessly to a small pocket-sized image processing computer. This computer then commands the glasses to send data to the implant via invisible infrared light. The chip converts the light to electrical impulses and conducts them to the optic nerve. You can see a video about how the system works below.

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Roll Your Own JBC Soldering Station

November 6, 2017 by 23 Comments

[Marco Reps] was soldering some boards with a lot of thermal mass and found his usual soldering iron was not up to the task. He noticed some professional JBC soldering stations that he liked, but he didn’t like the price. Even an entry-level JBC station is about $500 and they go up from there. He decided to build his own, but it did take awhile to complete. You can see two videos about the project, below.

How can you build your own soldering station and still claim it is a JBC? [Marco] noticed that the real performance of the iron came from the tip — what JBC calls a cartridge. In addition, the handle provides good ergonomics. You can buy the tips and handles from JBC for considerably less than a complete station. You just have to add the electronics to make it all work.

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Circuit Challenge: Two Transistor 3.3V Regulator

November 4, 2017 by 26 Comments

[Kevin Darrah] wanted to make a simple 3.3V regulator without using an integrated circuit. He wound up using two common NPN transistors and 4 1K resistors. The circuit isn’t going to beat out a cheap linear regulator IC, but for the low component count, it is actually pretty good.

In all fairness, though, [Kevin] may have two transistors, but he’s only using one of them as a proper transistor. That one is a conventional pass regulator like you might find in any regulator circuit. The other transistor only has two connections. The design reverse biases the base-emitter junction which results in a roughly 8V breakdown voltage. Essentially, this transistor is being used as a poor-quality Zener diode.

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Listening For Hand Gestures

November 1, 2017 by 15 Comments

[B. Aswinth Raj] wanted to control a VLC player with hand gestures. He turned to two common ultrasonic sensors and Python to do the job. There is also, of course, an Arduino. You can see a video of the results, below.

The Arduino code reads the distance from both sensors — one for the left hand and the other for the right. This allows the device to react to single hand gestures that get closer or further away from one sensor as well as gestures involving both hands. For example, raising your left hand and moving it closer or further away will adjust the volume. The right hand controls rewind and fast forward. Raising both hands will start or stop playback.

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Graphene Biosensors Are Extra Quiet

October 31, 2017 by 9 Comments

Graphene has attracted enormous interest for electrically detecting chemical and biological materials. However, because the super material doesn’t act like a normal semiconductor, transistors require multiple layers of the material, and that’s bad for 1/f noise especially when the transistors operate at maximum transconductance. Researchers have found a way to operate graphene transistors at a neutral point, significantly reducing 1/f noise while not impacting the sensor’s response.

The team created a proof-of concept sensor that could detect an HIV-related DNA hybridization. The sensor was able to detect very tiny concentrations of the material.

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Quick And Easy Solar Hot Air Balloon

October 30, 2017 by 63 Comments

[Becky Stern] likes to harness the power of the Sun. Most of us will immediately think of solar cells and other exotic solar energy techniques. But [Becky] shows how to make a hot air balloon using nothing but tape and garbage bags.

The idea is quite simple. You form a large envelope from black trash bags and fill it with air. Becky does that by just running with it, tying it off, and topping off with a little manual blowing. Once the sun heats the black bag, it floats.

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