Frequency Doubler
A frequency double can be built using just NAND gates and passive components. A good example with explanations can be found on this page. http://users.otenet.gr/~athsam/frequency_doubler_with_4011.htm.
Ok…ya, its in Greek, but the schematic is fairly self explanatory. Its the same sub circuit used in Ken Stones Sub Oscillator.
Follow the above links for the schematics. Kens uses a 330pf capacitor and 47k resistor. If you can imagine, these are pretty small numbers. Because of this, the frequency is doubled, but the size of the pulse is pretty small. In Kens sub oscillator, the output is sent to a counter, so the width is not particularly important.
See how tiny it is.
When I listened to it, it was hard to even tell it was an octave up. It just sounded like a mosquito buzzing, but running the samples through Audacity shows yep…theres the octave.
The source is at 100 Hertz or so:
The doubled frequency sample shows the amplitude higher now at 200 Hertz.
Here is a Sample of the original squarewave.
Here is the frequency doubled.
The small capacitor makes sense if your sending the signal to a clock, but if you want to hear a doubled signal, its not much to listen to. To fatten up the width of the pulse, I swapped one of the 330pf caps with a .01uf cap. You can see the bigger pulse next to the small one (the one controlled by the smaller 330pf cap).
Additonally, these caps have long leads so you can squeeze them with your fingers to get touch contact effects.
By squeezing the leads, you can here the pulse get bigger and bigger. As a bonus (of sorts) the capacitance gets high enough to force the doubled frequency into the original frequency. Mostly breaking the circuit, but isn’t that the point of circuit bending?
Here is what it sounds like:
