Programmable Gain amplification

Using Arduino General Electronics
1

Hi,
does any of you know how I can change the gain of an Op-amp connected to Arduino, just by using the code?.

Thanks

Marc

2

The Arduino only has PWM and digital outputs. The Due (discontinued) also has several analog outputs (DAC). Note there are programmable gain amplifiers available (PGA). Could also use a digital pot.

3

marco_p92:
Hi,
does any of you know how I can change the gain of an Op-amp connected to Arduino, just by using the code?.

Thanks

Marc

You probably need to use arduino output pins to make switches (relays) open and close..... which could switch extra resistors in parallel to existing resistors that controls the gain of your amplifier.

4

switching-op-amp-gain-resistances-how

AD595

LT1215 OP AMP

5

Sounds like you want a programmable gain amplifier like the MAX9939. Programmable by SPI.

700×606 25 KB

6

well I see there are a lot of possibilities. I should also give the amplified signal an offset, so to have it centered around zero (I have a square wave from arduino, between 0V and 5V). Any chance to do that?

7

The analog input bias voltage is usually set by voltage dividers.

8

You can also use a digital Pot to control the feedback in a standard Op amp.

9

The MCP4161 would work.

10

Is this for the project started here?
http://forum.arduino.cc/index.php?topic=414300.0

A few herz could be made with smoothed PWM.
The coil could be driven by a volume controlled audio/power amplifier.

You could start with the software to generate "a few Hz" sine wave from PWM.
Leo..

11