Fig.1 (left): the NCH Tone Generator is easy to drive and can generate a range of waveforms from 1Hz to about 20kHz.

Audio tone generators are very useful gadgets when it comes to setting audio levels and for testing audio circuits and loudspeakers. However, provided your requirements are fairly modest, you don't need dedicated hardware. Instead you can use your PC's sound card to generate a range of audio tones.

After all, why pay out big bucks when you can make a PC do the work for you? All that's required is a suitable program to make the sound card do its stuff.

One such program is "NCH Tone Generator" - a freeware utility from NCH Swift Sound. It works with all flavours of Windows, including Windows 3.1 (remember that?), Win95/98/Me, Windows NT and Windows 2000. You can obtain a copy from their website at www.nch.com.au/action/index.html and downloading tnsetup.exe (208KB).

Double-clicking this archive file automatically creates a folder called NCHTONE on your C: drive and extracts and installs three files: nchtoner.exe (the executable), nchtone.hlp (the help file) and uninst.exe (so that you can later uninstall the software). In addition, a shortcut to the program is placed in the Start menu.