oscillatorwave
I'm looking to create several sine waves on a single circuit. All must be under 20Khz frequency and each must be unique. Mostly it will be 5-10 frequencies needed.
As I found – almost all crystal oscillator are in Mhz frequencies and only one kind is 32Khz (which is still too high).
I should be able to get this wave on the other side using FFT.
Ideas? 🙂
Thanks
Usually 32768Hz quartz crystals are used in the clock applications. This standard is very widespread and these crystals are cheap and highly easy to find.
In order to switch the clock to work twice as fast, you will need 65536Hz crystal, that is not standard, not so common and probably not so easy to be purchased. For example my local distributor has 32768Hz crystals on $0.1 each and the next frequency available is 1.8432MHz
Another possible issue is the work of the internal oscillator with the changed crystal. It will probably work, but some capacitors might need to be replaced with other values.
And at the end, the last possible problem is the stepper motor of the clock. Is it capable of stepping twice as fast as usual?
You will need a 74 series IC (7400, 7404, 7406 etc.), two capacitors and two resistors.
Here is one possible circuit for a square wave clock generator:
Source: z80.info by Thomas Scherrer. Also check his site for more Z80 related information.
Best Answer
You could easilly divide the 32KHz crystal frequency with a Binary Counter (such as the 4040) to give 16KHz, 8KHz, 4KHz, 2KHz, 1KHz, 500Hz, etc...
Then some clever filtering can create a sine(ish) wave from each of those square waves.