Author: Steven Dufresne

Using a Lecher Line To Measure High Frequency

February 7, 2017 by 26 Comments

How do you test the oscillator circuit you just made that runs between 200MHz and 380MHz if all you have is a 100MHz oscilloscope, a few multimeters and a DC power supply? One answer is to put away the oscilloscope and use the rest along with a length of wire instead. Form the wire into a Lecher line.

That’s just what I did when I wanted to test my oscillator circuit based around the Mini-Circuits POS-400+ voltage controlled oscillator chip (PDF). I wasn’t going for precision, just verification that the chip works and that my circuit can adjust the frequency. And as you’ll see below, I got a fairly linear graph relating the control voltages to different frequencies.

What follows is a bit about Lecher lines, how I did it, and the results.

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Faking TV Remote Control with Paper and a Lighter

February 7, 2017 by 99 Comments

Cut slots into a piece of paper to represent the IR remote control bitstream for putting your TV into standby. Insert it between your TV’s IR receiver and the flame from a lighter, and pull the slots along to generate the coded pattern. Get it just right and you have a paper and lighter remote control. That’s just what [ViralVideoLab] did and you can see it in action in the video below.

Think of this as just the germ of an idea. Imagine how you’d automate this and extend it to include more commands. A wheel with the various bitstreams cut into the circumference comes to mind. A servo would turn the wheel to the desired command and something else would fire up the lighter just as the slots pass by. Now take it a little further. You already have a remote control with keypad and IR light. Hack that to talk to a microcontroller which would control the servo and the IR light. And there you go. A useless but fun hack (hint hint).

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Motion Detecting Camera Recognizes Humans Using The Cloud

February 6, 2017 by 31 Comments

[Mark West] and his wife had a problem, they’d been getting unwanted guests in their garden. Mark’s solution was to come up with a motion activated security camera system that emails him when a human moves in the garden. That’s right, only a human. And to make things more interesting from a technical standpoint, he does much of the processing in the cloud. He sends the cloud a photo with something moving in it, and he’s sent an email only if it has a human in it.

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Self-Lacing LEGO Power Shoe

February 1, 2017 by 12 Comments

Here’s a blast from the past, or future, reminiscent of the self-lacing shoes from Back to the Future Part II. [Vimal Patel] made his own self-lacing shoe using LEGO “bolted” to the shoe’s sole. We think these are cooler than the movie version since we get to see the mechanism in action, urging it on as the motor gets loaded down pulling the laces for that last little bit of tightness.

The electronics are all LEGO’s Power Functions parts. A Dremel was used to make holes in the soles to hot glue LEGO pieces for four attachment points. The attachment points are permanent but the rest can be easily removed. In case you want to look them up or make your own, he’s using the using the 8878 rechargeable LiPo battery box, the 88003 L-motor, the 8884 IR receiver, and the 8885 IR remote control. That’s right, these shoes are laced up under command of an IR remote control, well, provided the battery box is powered on. There’s a 1:24 worm gear reduction to get the needed torque.

This was a quick build for [Patel], done over two afternoons. He initially tried with the winding axle behind the heel but that didn’t work well so he moved the axle adjacent to the laces instead, which works great as you can see in the video after the break.

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Early Electromechanical Circuits

February 1, 2017 by 25 Comments

In the days before semiconductor diodes, transistors, or even vacuum tubes, mechanical means were used for doing many of the same things. But there’s still plenty of fun to be had in using those mechanical means today, as [Manuel] did recently with his relay computer. This post is a walk through some circuits that used those mechanical solutions before the invention of the more electronic and less mechanical means came along.

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Tesla Vs. Edison

January 25, 2017 by 174 Comments

The phrase “Tesla vs. Edison” conjures up images of battling titans, mad scientists, from a bygone age. We can easily picture the two of them facing off, backed by glowing corona with lightning bolts emitting from their hands. The reality is a little different though. Their main point of contention was Tesla’s passion for AC vs. Edison’s drive to create DC power systems to power his lights. Their personalities also differed in many ways, the most relevant one here being their vastly different approaches to research. Here, then, is the story of their rivalry.

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