Powering An Ultrasonic Transducer

January 30, 2012 by Kevin Dady 25 Comments

[Lindsay] has a wonderful writeup about a new toy in the shop, an ultrasonic transducer. The 28kHz, 70W bolt-clamped Langevin transducer by itself is not much use, you need a power supply, a horn to focus the energy, and a way to tune it. [Lindsay] starts off by showing how to find out the resonant frequency of the transducer, designing and building a high voltage high frequency AC power supply, and how to design a horn.

Not missing the meaning of DIY [Lindsay] casts and machines a horn for the transducer with a high level of precision as this will also tune the horn to the correct frequency. Once some brackets are machined the whole setup is put through some fun experiments in water and lemonaide, but the real purpose is to drill fine holes in glass for his home made Panaplex displays.

Join us after the break for a short video.

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DIY Ultrasonic Plastic Welding

January 20, 2012 by Brian Benchoff 40 Comments

Here’s something that may be of interest to all the reprappers, vacuum formers, and other plastic fabbers out there: ultrasonic welding of plastics. If you’ve ever wanted to join two pieces of plastic without melting them together with acetone or screwing them together, [circuitguru] is your guy.

Ultrasonic welder setups are usually reserved for companies that don’t mind spending tens of thousands of dollars on a piece equipment. There are smaller versions made for heat staking – melting plastic pillars into rivets on the work piece – and [circuitguru] was lucky enough a somewhat reasonable price.

Because the heat staking gun was a handheld unit, a rotary tool drill press was put to work. The end result is a relatively inexpensive way to join two plastic parts without screws, glue, or solvents. The bond is pretty strong, too. Check out the video after the break to see [circuitguru] join two pieces of a plastic enclosure and try to tear them apart.

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Cloud Mirror Adds Internet To Your Morning Ritual

December 18, 2011 by Mike Szczys 21 Comments

This mirror has a large monitor behind it which can be operated using hand gestures. It’s the result of a team effort from [Daniel Burnham], [Anuj Patel], and [Sam Bell] to build a web-enabled mirror for their ECE 4180 class at the Georgia Institute of Technology.

So far they’ve implemented four widget for the system. You can see the icons which activate each in the column to the right of the mirror. From top to bottom they are Calendar, News, Traffic, and Weather. The video after the break shows the gestures used to control the display. First select the widget by holding your hand over the appropriate icon. Next, bring that widget to the main display area by swiping from right to left along the top of the mirror.

Hardware details are shared more freely in their presentation slides (PDF). A sonar distance sensor activated the device when a user is close enough to the screen. Seven IR reflectance sensors detect a hand placed in front of them. We like this input method, as it keep the ‘display’ area finger-print free. But we wonder if the IR sensors could be placed behind the glass instead of beside it?

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Ultrasonic Combo Lock

December 14, 2011 by Mike Szczys 3 Comments

[John Boxall] took a different route for a single-input combination lock. This unit uses a Ping ultrasonic range finder to input a four digit code. It’s a hardware upgrade, but uses the same basic concept as his button-based combo lock. That design used an Arduino to measure how long you hold down a single button, with a one second pause between inputs, to enter the code. This one also uses timing to establish when each digit is read, but that digit is grabbed as the distance between your hand and the sensor.

There are things we like and dislike about the redesign. This is obviously much more expensive than other button-based locks like this garage door opener we built. If we were to run with [John’s] design, we might spring for the Ping sensor (because it’s a pretty cool input) and replace he character LCD with an LED or two. The other drawback that we see here is that it may be easy for someone to steal your code by watching from afar. Still, we love the project and think you will too after seeing the demo clip below.

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Ultrasonic Rangefinder As Scanning Radar

October 10, 2011 by Mike Szczys 14 Comments

Ultrasonic rangfinders are a cheap and easy way to gather obstacle avoidance data. When added to a servo motor they form something of a scanning radar for near-proximity objects.

In this implementation, [Rui Cabral] is driving the servo, and collecting data from the sensor using a PIC 18F4520. The servo rotates 180 degreees, taking sensor measurements in increments of nine degrees. If it discovers obstacles, the distance and orientation are recorded. Feedback is displayed on a 20-LED bar graph display which shows a moving LED to track the sensor orientation, with LEDs remaining lit whenever an object is found. Right now the obstacle data is pushed over a serial connection with a PC, but could easily be injected into navigation logic for a robot in order to triangulate a path around the obstruction. You can see [Rui’s] project in action after the break.

We looked in on the same concept with a different display technique a couple of years back. That hack used an Arduino and Processing to map sensor data with a traditional green sweep display.

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Boost Your Garden’s Output Using Ultrasonic Mist

August 11, 2011 by Mike Nathan 97 Comments

ultrasonic_aeroponic_growing_rig

If you enjoy gardening, it’s never too early to start thinking about next year’s growing season. [Jared Bouck] over at InventGeek loves his tomatoes, but the slow grow rates of his dirt-bound plants were less than impressive. To get things moving faster, he created a low-cost aeroponics system that uses ultrasonic mist to produce some pretty impressive results.

The construction process of this ultrasonic aeroponics rig looks dead simple, and [Jared] said that he had everything assembled in about half an hour. A cheap ultrasonic mister was mounted in the bottom of a plastic tub, and holes were cut in the tub’s lid to make room for his growing baskets. Tomato seedlings were wrapped in rock wool and placed in a clay growing medium, suspended over the water bath. The mister was turned on, and after just a few days, the results were obvious.

In the last step of his tutorial, he compares his aeroponically grown plant to one grown in soil – the difference is unbelievable. Considering how reasonably priced his setup is, it seems like a no-brainer to start growing your entire vegetable garden this way.

Harvesting Ultrasonic Sensors

February 3, 2011 by Caleb Kraft 25 Comments

With many modern cars coming equipped with an array of ultrasonic sensors mounted in the bumpers, it stands to reason that many junk yards have them too. [jimk3038] points out that, unless they’re crushed, they’re probably good. The list of features on these is pretty long, including being short proof, water proof, EMF proof and fast. These tough little suckers can be used in a multitude of projects and can have a range of roughly 2 meters. [jimk3038] documents in great detail how to use these things as well as offering some sample code to get you started. Why didn’t we think of this?