Mixer - Part 2 - Using the OPA2134

Hi,

This is just a quick post showing my tests of the OPA2134 OPAMP from TI.

Datasheet - http://www.ti.com/lit/ds/sbos058a/sbos058a.pdf

I'm not sure whether or not I'll use this in the final design but as its touted as a "High Performance Audio Op Amp" I figured it's not a bad place to start.

At around $7 AUD its not necessarily the cheapest Op Amp around.

It's available in single, dual and quad versions but as I'm after individual control of the Left and Right channels, I chose the 2 channel 2134.

Now to the breadboard!

If you read the previous entry I explained how to setup a split power rail (and the reasons why you need one) to supply the + & - voltages used by the chip. Whilst not shown in this quick example, I used a TLE2426 rail splitter IC to supply +6V and -6V from a 12V power supply. I'll show the use of this chip in detail in another entry.

Rather than go through the theory of the values used I've decided to just give a quick rundown of the components I used.

  1. Microphone - Negative to ground, Positive to a 0.1uF capacitor.
  2. Capacitor Negative to a 47k resistor which then goes to Pin 3 or +In A
  3. Pin 2 (-In A) goes to a resistor divider. There's a 1k resistor to ground a 2.2k resistor to pin 1 (Out A)
  4. Pin 1 (Out A) then connects to the positive of the speaker.
Now to test it! 

Sending a sine wave signal using a wave generator and measuring the output on the oscilloscope gives us the following result.


The green wave form is the input from the wave gen and the yellow is the output from the OPA2134. It works! Based on the Pk-Pk values it would appear we're getting a bit over 3X gain increase. For my use , at least at the moment, that is ample.

Well there you go. Hopefully you've found this entry useful and please leave any questions or suggestions in the comments section.

Thanks


Justin 

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