amplify a sine wave

hii member on this forum, I have a problem, I make a sine wave generator and the project to generated wave is work, after generated wave I want to connect it to a amplifier, I have tried, but output signal on amplifier is no sine wave generator but just straight line,
after I research that sine wave that I make is not enough / not able to make transistor in amplifier to be ON condition,
So I want to ask, how to make sine wave greater then able to operated in the amplifier?

Use an op-amp duel op amp One half to be amplify the signal the next half as a buffer stage "Unity gain " Non Inverting mode TL082 or similar will do the job very efficiently

In this project I used TLO82 to make sine wave, then sine wave is formed, but the wave not able to make transistor to be ON condition,
please tell me clearly sir,
sir, actually what the wave is produced by the power amplifier / amplifier?

Hi Ahmad,
You are not getting the output on the amplifier, probably because the the output of the generator does not have enough power to handle the input imeadance of your amplifier. Hard to tell but that is waht it sounds like. Based on your answer to the other persons response, you are trying to drive a transistor input to the amplifier circuit. What is the voltage peak to peak output of the generator? I has to be enough to turn on the transistor,

The suggestion of using another dual opamp was a great suggestion, one as a buffer with unity gain directly on the output of the generator, take the output of that to the input of the second opamp in the package. Set this opamp up with enough gain to give you the volatge and currrent to bias the transitor to the on state.

This is a common problem and why we opamps as a buffer. You can try to take the output of the buffer direct to the amplifier first, to see if that is all you needed.

Hope this helps!
Bob

thanks Robert,
my sine wave have 2volt peak to peak,
I have tried use single op amp (741), my output signal (sine wave) generator is connected to pin 2 op amp and pin 3 ground, I found square wave ( no sine wave), and from op amp to amplifier, then signal shown by oscilloscope just straight line.

what I must need a preamplifier ?

thanks for discussion sir, I'll try your idea.

There is a lot of missing information in your request:

1. By how much do you want to amplify this sine wave?
2. Do you want to amplify voltage, current, or power?
3. How are you coupling the output of your sine wave generator to the transistor? Direct coupled? AC coupled?
4. Do you know how to bias a transistor for linear operation (I'm assuming you want to amplify your sine wave with minimal distortion)?
5. Do you know how to set the gain of a common-emitter transistor amplifier?
6. Are you even using a common-emitter transistor circuit, or is this intended to be something like a push-pull power amp, or ???

A schematic would help, also.

Hi Ahmad,

if I may quote you :

_"I have tried use single op amp (741), my output signal (sine wave) generator is connected to pin 2 op amp and pin 3 ground, I found square wave ( no sine wave), and from op amp to amplifier, then signal shown by oscilloscope just straight line"_

You cannot connect directly to the input pins of an OpAmp without a feedback network. Otherwise the OpAmp will just act like a comparator and you will get a square wave output - just like you have.

Look on the Wikepedia link http://en.wikipedia.org/wiki/Operational_amplifier and see what I mean, the second diagram is like your arrangement and operates as a comparator, the third diagram has negative feedback and is what you need. Read about this and choose resistor values which set your gain.

I hope this helps,

Jeff