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ThomasVDD‘s DIY capacitance meter uses a 555 timer circuit as a monostable multivibrator, where the output pulse interval depends upon the value of the capacitance to me measured. An ATTiny84 is used to measure the duration of the 555 timer output pulse, and thus compute the capacitance, which is then displayed on a seven segment LED display module. A while ago I also posted a tutorial on how to measure capacitance with a PIC microcontroller.
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This cellphone-controlled toy car is controlled over a phone line by sending DTMF tones from another cell or landline phone. This Project implements the functionality of IVRS (Interactive Voice Response System) technology. The car is controlled by a Mobile phone that makes a call to the phone attached to the Car. During the call, if any key is pressed, a DTMF (Dual Tone Multi Frequency) tone corresponding to the key is sent at the other end. The received tone is processed by the Atmega16 microcontroller with the help of MT8870 DTMF decoder. The decoder converts the tone into an equivalent
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Pete Mills’ has shared his cool-looking DIY Nixie clock design on his personal blog. His design is based on Atmega328 and uses software driven RTC and voltage booster to achieve ~175V DC for Nixie tubes. Nixie tubes are cool. They have great aesthetic appeal with their difficult-to-photograph, warm orange glow, and dem curvy numerals. They add an organic je ne sais quoi to a hobby with ostensibly digital design cues. Further, they pose technical challenges in the way of producing and switching the ~175 V DC needed to light each tube element. And as far as I am aware, there are
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Dmitry Griberg’s musical holiday card project is really cool and plays a full song in full fidelity from an SD card. The project uses Attiny85 microcontroller and a 4-MOSFET amplifier circuit, both powered from a LiPo battery. The complete circuit is enclosed inside a CD case, and a simple flexible metal strip is used to make a contact sensor that will activate the player when the CD case is opened. The songs are saved on the SD card as WAV files with 32KHz sampling rate and 8-bit samples. Here is a demo video of this:
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Two Cornell University students, Michael Wang and Jennifer Qian, have built Selfiebot, a personal photo companion that will capture your special moments autonomously. It consists of a physical selfie robot unit with camera holder (webcam in this example) that can pan and tilt the camera for proper positioning, and a control module residing in a laptop computer that relays pan and tilt commands to the robot based on the feedback received from the camera. The user gets control of various settings such as image properties, centering properties, and photo taking parameters. Michael and Jennifer write, We have designed and constructed an
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