Oscillator Sine Square

sine wave generator?doubt?

friends how can i make a circuit which can take input +12V
DC and a loudspeaker connected to the output of the
circuit,i should hear a constant tone(constant AC voltage),
from the loudspeaker.i want the output to be SINE WAVE not square, can u please suggest me
some ideas to do it .thank u,do u think this can be done by a wein bridge oscillator of 40Khz

Any sine wave oscillator will work but 40kHz is too high of a frequency. You gotta have something in the audio frequency spectrum if you want to be able to hear it.

A look at what is currently available on eBay

HP 209A Sine/Square Oscillator Operating & Service Manual, 3115B-1 US $29.99

FARNELL FREQURNCY SINE SQUARE OSCILLATOR LFM3 50/60Hz US $88.00

Items recently purchased from this site