Here’s a project that I’ve been working on for a class recently. This is a very basic 2m AM Transmitter that operates from 144.25 to 144.31 MHz. It does put out a low powered RF signal (around 5 mW PEP) that has been copied over 1 mile from the transmitter. This is an ongoing project that will likely evolve into something else, so I should get time to do some more in-depth posts as time goes on.
a practice in designing an oscillator. this particular circuit employs a 2N2222A transistor on 6 volts. i used this Electronic-Tutorials.ws page to design the circuit. there were many reasons for this experiment, but the most immediate was to act as a simple CW practice oscillator. the final circuit looks something like the following.
Very short video of the waveform captured using Xoscpe of the PT2399 applied to the LM386 square-wave oscillator. Sorry for the bad focusing. I was in a rush. I just needed a visual capture for later analysis.
[audio:http://abrammorphew.com/notes/wp-content/uploads/2011/06/osc_delay.mp3|titles=i just broke the gameboy]
…and here’s a clip of the aforementioned wave from from around the same time.
Here’s a small LM386-based square-wave oscillator built from the following schematic. I replaced the 30k resistor with a 50k Potentiometer from my stash of parts which then, of course, acts as a pitch controller. The following audio is some track recordings made in Ableton 8.0 with a little filter on one track and some reverb the air-raid siren sounding noise.