uaefame

Hello there, I want to do a project where i can control the frequency of the speaker. I want to know how can i control frequency of the speaker.

For example apply a certain voltage to control different freqency?

Can some one give me a clue about it? or a website that explain it?

Norlin

Try this:


Adjust R2 to adjust the frequency

uaefame

Thanks norlin,
I wanted to control the frequency of the speaker. In simple words, i wanted to control the viberation. I know your diagram is for tone, i wanted viberation.
8ohms speaker i began understanding how speaker can be classified.
Thanks in advance

crutschow

All vibrations have frequencies associated with them which are tones. By vibration are you meaning a low frequency tone? If so, what frequency?

Abeer_engjbr

You can use an RC circuit in parallel and change R , or you may use a crystal osclliator as far as I know.

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.

Nigel Goodwin

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

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uaefame

I will give it a try Btw, what value of capacitor you suggest.
For Q1 B2 is the .....(collector)??? B1 is the ....(emitter or base) ??? E is the ...(emitter)?? can you point this out please and what type of transistor if its a transistor?

Thanks in advance

crutschow

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.

rjvh

your frequency range should be lower if you want to folow it with you eyes
(1Hz to 20Hz)

the frequencys you talk about is posible to see with a trill plate and sand on it but folowing the speaker with your eyes is imposible at frequencys higher than 25 Hz

Robert-Jan

audioguru

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

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Hero999

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

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uaefame

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

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Hero999

Have you searched Google?

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

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