Mixer

Thread Starter

Falco1

Joined Apr 29, 2017
5
Hello,
I would like to ask how does an additive mixer work?
There must be a non-linear element, but I do not know why.
How is it not sum signals without the non-linear element?
 

Thread Starter

Falco1

Joined Apr 29, 2017
5
So are resistors used for additive mixing?
So, if I want to add signals, will I put them through the resistors?
And how does mixing work on a semiconductor component, such as a transistor.
 

Papabravo

Joined Feb 24, 2006
21,227
The secret to mixing can be found in the trigonometric identities for the product of two sinusoidal signals of different frequencies.

\(sin A cos B\;=\;\frac{1}{2}sin(A - B)\;+\;\frac{1}{2}sin(A+B)\)

and

\(cos A cosB\;=\;\frac{1}{2}cos(A-B)\;+\;\frac{1}{2}cos(A+B)\)

Multiplication is the nonlinear operation that produces this result.
 

Thread Starter

Falco1

Joined Apr 29, 2017
5
thank you all
Does this mean that the signals are multiplied by additive mixing?
So will the difference and sum component be created
 

Papabravo

Joined Feb 24, 2006
21,227
thank you all
Does this mean that the signals are multiplied by additive mixing?
So will the difference and sum component be created
No, only a nonlinear operation, e.g. multiplication, will produce frequency components at the sum and difference frequencies.
 

Kermit2

Joined Feb 5, 2010
4,162
The additive and difference signals are produced and the original signals remain present as well. In a two input mixer there are 4 signals at the output to choose from. The stage it feeds will select for one signal through component choice.

Active mixers can boost a freq and/or block one but the basic principles still apply.
 
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