All posts on March, 2008
Posted on 20 Mar 2008
The basic idea of TinyProjector is to create the smallest possible character projector that can be either integrated into mobile device, or linked dynamically with wireless RF connections like serial low range transceivers.It used laser diodes salvaged from cheap key chain laser pointers.
A micro motor with a single swiveling servo arm, making a continuous full 360-degree rotation, drives the deflection mirror, resulting in a 38-degree left-right sweep. This leads to an unusually high overall laser projection angle of 104 degrees.[more]
Posted on 20 Mar 2008
The Scopetris is an AtMega32 was equipped with R-2R ladder D/A converters for controlling the beam of an old oscilloscope. To get some fun out of the setup, a Tetris clone with chain reactions was implemented. Beat the highscore[more]
Posted on 20 Mar 2008
The hardware is very simple, and is based around an Arduino board that is using a bit-banging SPI technique to write data to a 100KΩ digital pot (model MCP42100). Approximately 7 of the 8 bits of data actually change the value of the filter (this could be due to the resistance value of the pot).[more]
Posted on 18 Mar 2008
This is 75 Meter QRP SSB Transceiver.The transceiver switches the 4-element 1500 ohm xtal BPF ends between the inputs and outputs of the two SA602s to reverse the signal flow for R/T operation. Since no IF amplifier is used in the design, 20 dB of additional receiver gain is produced by the 2N2222 receiver RF amplifier, while automatic gain control (AGC) is produced by the peak DC swing of the LM386 output passed through a rectifier and filtered by a capacitor and fed to the gate of a BS170 enhancement mode FET acting as a variable resistor across the input of the LM386.[more]
Posted on 18 Mar 2008
This amp is rated at 100W into a 4 Ohms load, as this is typical of a “combo” type amp with two 8 Ohm speakers in parallel. Alternatively, you can run the amp into a “quad” box (4 x 8 Ohm speakers in series parallel and will get about 60 Watts. For the really adventurous, 2 quad boxes and the amp head will provide 100W, but will be much louder than the twin. This is a common combination for guitarists, but it does make it hard for the sound guy to bring everything else up to the same level. [more]
