# very very low sine wave amplifier

#### mostaghfir

Joined Dec 29, 2010
10
Hello ... Sorry for my mistakes in English
I want to complete the circuit for the generator sinusoidal signals low of 0.1 Hz to 50 Hz with an output producing 0-10v 200mA for explinning the nature of AC current .... almost i used integrated circuit xr2206 and everything is fine for the purity of the signal ....the problem is on the amplification of the very low frequencies between 0.1hz to 2hz a big distortion loses the signal ... the attached pdf file swho the amplier circuit using

please : i ask you to help me to accomplish the perfect amplification circuit

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#### R!f@@

Joined Apr 2, 2009
9,890
You would need an amplifier that can go down to 0Hz.
Audio Amps cannot go that low, unless it is designed for that.
Think Sub Woofer amps

#### atferrari

Joined Jan 6, 2004
4,730
As-tu vu cette remarque ci?

It would be good if you show your circuit (signal generator).

#### DickCappels

Joined Aug 21, 2008
10,104
Can you describe the distortion?

Just a guess from the schematic, but does the distortion look anything like crossover distortion (below)?

Or does it look like clipping (below)?

#### Picbuster

Joined Dec 2, 2013
1,045
Use a PIC to generate sinus put that in a dac and use an opamp ( one chip version like the INA126)
At this point you have a correct shaped Sinus. next step is to use a paired set pnp/npn transistors.
make sure that your supply is > then wanted 10V ( eq 12V= +6 and -6V) set the opamp gain so that the amplitude =10V.
Correct the offset and make sure that you eliminate non linearity in the last stage.

#### AnalogKid

Joined Aug 1, 2013
10,785
My guess is that you have a lot of crossover distortion, like the first image in post #4. And, there might be bursts of oscillation in there. The circuit you have is a good approach, but it has a very poor output stage. Do you want to build a better amplifier, or buy one?

ak

#### wayneh

Joined Sep 9, 2010
17,471
I believe there are op-amps capable of 200mA directly without an additional output stage? That would simplify things quite a bit.