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Homemade Radio Frequency Generator

Electronics technology offers several different ways for the home hobbyist to produce radio frequency signals. You can make traditional oscillators from transistors and other discrete parts, or take a more modern approach and make radio signals from computer-based circuits.

Colpitts and Hartley Oscillators
- A few basic electronic designs, sometimes based on a single transistor, can easily produce radio frequencies. Each of two different circuits, the Colpitts and Hartley oscillators, can generate a sine wave having a frequency determined by a set of coils and one or two capacitors. Adding a quartz crystal to the circuit makes the frequency highly accurate and stable.
Function Generator
- A circuit called a function generator produces sawtooth, triangle or pulse waveforms, in addition to sine waves. Although a function generator produces a variety of wave shapes, it is only moderately more complex than a Colpitts oscillator.
Digital Synthesis
- Many current radio designs generate signals by repeating at high speeds a sine wave stored in computer memory. This approach produces an accurate frequency and wave shape that you can control from software. While these circuits are complex, you can make or buy them at low cost.

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