I need a sound

[Hrothgar]

Can anyone link me some utilities or mp3 files for a steady loopable sound in the 8 - 22 khz range? I'm wanting to use it for pulsed dc timing. Using a cheap stereo and an mp3 player is preferable to shelling out money for fancy equipment.

[dR-Green]

Get a free VST host or sequencer:

Free VST Host Application Roundup! - Bedroom Producers Blog

Choose from the list above, such as this one:

SAVIHost

Then get a free VST instrument plugin that will generate the sounds (there are hundreds available):

LinPlug Virtual Instruments - Alpha

http://www.linplug.de/stock/alpha/FreeAlpha%20Installer%20330.exe

Set sequencer/host MIDI track output to trigger synth plugin. Program sequencer to play desired note = frequency, select waveform etc on plugin interface.

Piano note to frequency converter:

Audio Downloads : Frequency Converter /// AnalogX

You can also use this to turn the computer keyboard into a virtual piano keyboard (MIDI controller) to trigger the synth plugin:

VMPK. Virtual MIDI Piano Keyboard

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Alternatively you can use MathSounds

[kenssurplus]

I prefer to use this spec lab software:
DL4YHF's Ham Radio and Homebrew Homepage
as it allows 3 independant oscillators for output signal and allows you to view input in a spectrum alalyzer format.