Need a circuit! Sinewave Generator

Gordon posted:

You aren't going to find an oscillator that can directly drive any speaker very well.

However, you will find some fairly good function generators such as the B&K

3011B on eBay. They can drive an amp of your choice. Many of them, including the 3011B, have a frequency counter, and the bonus is that you can sweep a range of frequencys if you like that method. If you have a scope, you can use the ramp output of the function generator to drive the horizontal channel so you can plot frequency to the horizpntal channel and amplitude to the vertical. It gives you some nice options.

Don

Check out my freeware DaqGen software. It uses the sound card in your computer to provide a complete low-distortion audio signal generator. Besides pure sine waves, you can generate much more complex test signals like narrow bands of noise. You can use slow frequency sweeps to watch for resonance.

DaqGen is the signal generator portion of the upcoming Daqarta for Windows, which will be released in a few months (hopefully!). Daqarta will also allow you view the response to the generated signal, so you could have the entire resonance analysis in one view, automatically.

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

The software mentioned above is capable of rather complex outputs, patterns, and is as good/better than commercial (read: $$$) offerings I've looked at.

Well worth a look if you need that sort of thing.

Louis--

********************************************* Remove the two fish in address to respond

Bob,

Can you indicate how the Windows versions is coming along? (Or, can the DOS version run on Windows XP?)

Thanks and regards,

Mark

DaqGen is a Windows-only signal generator program that has been available for about a year. It will run fine on XP.

Daqarta does signal acquisition/analysis as well as signal generation.

Daqarta for Windows does will hopefully be ready in a few months, and will run on any Win9x, NT, 2K, XP etc platform.

Daqarta for DOS will only run on Win9x or earlier because it needs real-mode DOS. But the biggest problem is that there is no such thing as a standard DOS sound card driver, so I have had to write custom drivers for each card supported. Since Creative Labs dropped all pretense of supporting developers for anything beyond ISA bus, that's where I quit. So Daqarta for DOS requires an ISA-bus Sound Blaster. (Or one of a huge family of legacy ISA-bus lab-type data acquisition boards, or a simple 8-bit "board" you can build yourself.)

I'll post a note here when Daqarta for Windows is ready.

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

Hi, and thank you all for your information and suggestions. I eagerly await the full version of the software, which no doubt will be extremely useful for analysing the sound/respose of finished violins.

Unfortunatley, the 'kit' I need is for my workshop (no computers there). Basically, it will be a worktop with a woofer set into it, and the violin belly or back supported at nodal points above it. Sprinkled with the fine grains of tea from a tea-bag, when cranked up to resonant frequency (with quite high amplitude), the plate vibrates and the tea grains form 'Chladni' patterns on the plate - it's really the only way there is to determine symmetry of vibration across the plates.

Many thanks, Gordon

You may want to consider getting an old "junker" computer to keep in the shop, and run Daqarta for DOS on it. You can pick these up really cheap, if not for free, and the only hitch is finding a compatible sound card. Note that the LPTX driver module contains complete instructions for a super-simple 8-bit D/A that plugs into the printer port... just a handful of resistors. It will be roughly comparable to a lab-type function generator as far as distortion goes... around 1%. It would be just fine for this application, in the event that you can't locate a Sound Blaster or other supported card.

If you can find an ISA-bus Sound Blaster, then the Daqarta analysis functions will be really handy as well.

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis