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Tuesday, December 10, 2013

Pocket Dice Kit Model K-28 by Elenco

The Pocket Dice Kit is made up of fourteen LEDs to represent two dice, and three main circuits: Clock Oscillator, Presettable Counter, and Decoder Circuit. There are seven LEDs per dice for the six possible dice combinations. To create a number on the dice (LEDs), a switch is pressed down, causing a short, and producing a number. The Clock Oscillator is an IC that consists of two NAND gates that are digital integrated circuits that inputs are tied together to form an inverter circuit. The frequency of the oscillation is about 60 cycles per second producing a square wave. By pressing the switch one causes a short and the feedback stops hence the oscillator halts. The Presettable Counter function are two IC. These two IC convert the square wave of the Clock Oscillator. Every time the clock puts out a pulse, the counter will change its output. The two counters convert the clock pulses in six combinations of "1" and "0". The Decoder Circuit takes the output of the Presettable Counter and lights the correct LEDs. It consists of a NAND gate and an OR gate. 






Friday, December 6, 2013

Lie Detector Kit Model K-44 by Elenco

The Lie Detector Kit is an oscillating circuit based on the theory that when one is lying there is a change in galvanic skin resistance that would cause the oscillator frequency to increase. This kit uses the IC 555, and one can change the sensitivity with a low and high switch and a in series trim pot. In operation, a person would hold a wire connected to washers in each hand. When the person is lying to a question there GSR changes causing the frequency to change or the sound to increase to indicate lying. In testing this theory I found that it did not work. Lastly, this kit can also be used as a moisture indicator, and in the video, I demonstrate that this idea is very promising.  


Testing
Water Detecting

MK193 3x3x3 3D LED Cube by Velleman

This is Velleman's 3x3x3 LED light Cube uses a 9v battery; in addition, this is a programable LED light cube. Velleman recommends starting with this kit before assembling the there 5x5x5 LED Cube.