Designing a frequency multiplier

[eddy66t6]

Hi, I'm working on a project and found this circuit for a frequency multiplier that could be of use to me. I would be dealing more in the Hz range than the MHz range, and was wondering if anyone can point me in the direction of a good tuitorial or the like for it... What are the drawbacks to such a circuit too?
I'd be dealing in audio signals so I'd want to keep noise to a minimum too...
Thanks
http://electriciantraining.tpub.com/14181/img/14181_95_1.jpg

[c4757p]

It's a tuned circuit. It's set to multiply 1 MHz to 2 MHz, and it's not going to do anything but that unless you retune it. It's basically a 2 MHz oscillator being excited by a 1 MHz input. (And you'll need one massive inductor to use this circuit in the Hz range.) I don't think this will be useful for you.

You might find something like the 4046 PLL of more use, though you'll need a bit of extra circuitry, and it's square wave only.

[eddy66t6]

Yeah, I thought so, I was hoping for a sine wave multiplier... I shall certainly take a look at the cd4046 though

[c4757p]

If your specific problem is "doubling a low frequency sine wave", you can use an analog multiplier, because a sine wave squared is a sine wave of double the frequency. Those specific ones aren't cheap, but you might be able to find a cheaper one.

[w2aew]

The multiplier is a good route to explore.  The typical RF techniques for frequency multiplication can get into unwieldy component values at low frequencies.  If you want to learn more about the 4046, you might want to view my video on the basics of PLLs and frequency synthesis, which uses the 4046: