Think Create | Deqing Sun

My gadgets

Sigma Delta DAC DDS

by on Mar.13, 2011, under My gadgets

To build a DDS we need a DAC. As a hobbyist DDS, R2R Resistor Ladder Networks or PWM is often used. PWM waves generated by a built-in module in the micro-controller may be the most simple and cheap choice. But when we have to generate the wave with our own code, we can also choose the Sigma Delta modulator to convert the N-bit PCM data to one-bit PPM stream for output.


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8pin AVR fuse resetter

by on Dec.26, 2010, under My gadgets

An 8pin AVR only has 5 IO pins in default which is not enough in some applications. The reset pin can be treated as the additional pin at the cost of disabling the ISP function. Then the chip can only be programmed by a High-voltage Serial Programmer. So this device is useful to reset the fuses in AVR and enable them to be reprogrammed again.
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Pepper Protocol Analyze

by on Dec.25, 2010, under My gadgets

Pepper is tiny IO board using USB. It is compatible to Gainer, which can be easily controlled by Flash, Max/MSP or Processing. The Pepper is a good choice to link the computer and the physical world without concerning the programs outside the computer. It is more efficient than Arduino in some simple applications.
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Experience “Octave illusion” with Arduino

by on Dec.21, 2010, under My gadgets

The original design is on Elektor, “Ear boggle”. In that case, a 40106 is used to output alternating square waves. Although that circuit is simple, it can be ever simplified by using a micro-controller. I used an Arduino board to output the sound in sine wave form which is the same to the original experiment by Diana Deutsch. In addition to the Arduino, two resistors, two capacitors, a 3.5mm jack and an earphone are all we need.
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Digital variable resistor

by on Nov.28, 2010, under My gadgets

Resistors are essential parts in a circuit. When we prototype our ideas, we need various kinds of them. But it is annoying to put the resistors back to their original pocket after the experiments and it is a bit wasteful to put them in trash bin. With this digital variable resistor, the problem is solved.
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Perfboard in 3D

by on Nov.15, 2010, under My gadgets

Perfboard is widely used in prototyping. But it is not easy to expand. Besides, most boards are flat and boring. This snowflake perfboard can solve the problem.
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Neon light controller

by on Nov.11, 2010, under My gadgets

Neon lamps are easy to use, but hard to control. A neon lamp with a resistor can be lit directly by a wall plug. There are neon bulbs which sports flowers and leaves. And they can be good ornaments for our home. Unfortunately, they are hard to control its lightness. So I modified a electrical ballast from a fluorescent lamp to control its lightness.
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Solar pummer with breathing light

by on Nov.09, 2010, under My gadgets

This is an original designed BEAM bot. It stores sun light during the day and “breath” through the led at night. The whole circuit was free formed and no board was used. Copper wires form the structure and hot glue strengthened the joints.
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Smart ruler

by on Nov.08, 2010, under My gadgets

In order to measure length, we use a ruler. If we want to read the result easier, we can use a digital caliper. But if we want to measure the graphics without suffering reading the marks, we can use this gadget.


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Solar toy car with hand switch

by on Nov.07, 2010, under My gadgets

The original car only has a solar panel and a motor. That means it will run under strong light. I added a boost converter, a battery pack and control circuit. So it can store the energy from sun and be started and stop simply with our hand without a mechanical switch. A quick push can start the car and it will stop after hitting an obstacle.
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