Hello, I am interested in building my own AC generator for experimental purposes. I want to be able to vary the frequency. Also I want it to be able to produce really high frequencies. Does anyone have any cool ideas of how to put something together easily and cheaply? Also what is the highest frequency I can hope for? Is there a limit? I have done a lot of mechanical engineering subjects but not much electrical. Is it possible to generate AC at say 2 GHz?

 

The device you want is called an oscillator. 2 GHz is well within the range of possibilities. With no idea of your application, I might suggest you check with the ARRL website, or google "high frequency oscillators".

A cynic might suggest the bst way to come up with an oscillator is to try to design a linear power supply regulator.

 

Low frequency oscillators are relatively easy to build, and require very few components.

The higher you go in frequency, the more difficult it is to design, and the more expensive the components get.

For example, your typical SMT 0603 ceramic capacitor isn't an ideal capacitor. It may be rated at 50pF, 1%. That 50pF is measured at around 1kHz, and actually stays fairly close to that for many MHz. However, the higher in frequency you go, the more capacitance you'll get. That same 50pF cap will measure in excess of 150pF at 500 MHz. If that cap is a part of a resonant circuit, it may still resonate - but not at the frequency you thought you'd get.

Start with the low frequency stuff first, then gradually go higher. Keep your power levels low, unless you want the FCC breaking down the door and confiscating your equipment.