Originally Posted by uaefame

Yes indeed i am trying to use low frequency for my application something around 11Hz - 1kHz. I want to visualize the viberation. If you know about a circuit that will work please guide me. I am looking forward for an answer.

The circuit above will do what you want, alter the value of the timing capacitor to get the range you require.

The oscillator circuit posted by Norlin is not a sinewave oscillator. It uses a unijunction transistor as a relaxation oscillation whose output is a series of pulses. Thus the sound will have many harmonics as well as the fundamental frequency.

A unijunction transistor is an old device type specifically designed for oscillators. B1 and B2 look like about a 6k ohm resistor between the terminals. As C1 charges through R1-R2, the voltage on E rises until it reaches the transistor standoff voltage (typically about 70% of the voltage between B1 and B2) at which time E suddenly changes from a high impedance to a low impedance and discharges the charge on C1 through B2. After C1 is discharged, E goes back to the high impedance state and the process repeats.

If you prefer a purer sinewave it can be generated with a function generator IC such as the Intersil ICL8038.

Microprocessors with a pulse-width-modulated (PWM) output could also be programmed to generate a low frequency sinewave.

A strobe light will allow a speaker to be seen at nearly any frequency.

Good luck getting hold of a unijunction transistor.

The simplest oscilator circuit is the reverse bias oscillator. You can change the frequency by varying the capacitor and resistor values.
http://www.geocities.com/CapeCanaver...s.html#REVERSE

I am interested to know how can i generated sinwave using microchip 16F84, If its possible guide me. Becasue the input to the 4ohms speaker that i will buy is AC therefore i am interested in know how can i do generate sin wave using 16F84.

Thanks in advance

Have you searched Google?

http://www.google.com/search?client=...utf-8&oe=utf-8