For the past year and a half I (Mark) have been part of an Ann Arbor, Michigan based group named GO-Tech. The common thread among the group members is that each of us is interested in making things using technology (combining hardware, software, metal, wood, etc. ). I refer to it as Do It Yourself Tech (DIYTech). The group meets monthly to pres
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ent projects and have interesting discussions. I attend when I am able; it is a fun, enriching after hours activity. At the most recent meeting that took place on January 13th, there was a contest in which everyone was invited to build a device and demonstrate it at the meeting. As Dale (the group organizer and leader) described it: The Five-Minute Timer Contest goal is to design a timer to time presentations at our meetings. It should semi-accurately time the presenter, and give some audible or visual indication when their time is up. Portability, coolness, and robustness will be helpful. Cool prizes supplied by O`Reilly, publishers of Make. I created a traffic signal based timer that I named 5 Minute Signal. The time is actually settable to one minute and up (in one minute increments). To build it, I hacked an inexpensive plastic traffic signal (about one foot tall) that I purchased from Oriental Trading Company. To control the signal and provide accurate time keeping, I used my trusty Bare Bones Board (BBB) Arduino-compatible microcontroller board. The hardware is fairly simple (the BBB, a pushbutton control switch, and 3 relays to control the red, yellow, and green lights) and the software was fun to write. I put the whole thing together the weekend before the GO-Tech meeting. Basic operation is as you would expect: Push the button to start the timer. When the time interval is set to 5 minutes, the green light will...
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The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
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The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
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This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
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