modified 5 years ago

Non inverting signal mixer with 1 opamp

01:28:35

Passively mixed by the 3 of 5M6 resistors then the opamp makes up the losses in the mixer. Extra inputs could be added via 5M6 resistors tied at the non inverting input of the opamp. For each additional input the opamp gain needs to increased by 1 ( e.g. 4  inputs needs X4 gain, 5 inputs needs X5 gain, etc. )

published 7 years ago

hurz

7 years ago

5.6MOhm is a little high in impedance and cause quite some bandwidth limitations http://everycircuit.com/circuit/5114921573679104

gasboss775

7 years ago

Yeah, that's a good point, the choice of 5M6 was to reduce interactions between channels as varying the 100K pots only has a slight effect on adjacent inputs with a lower value of resistor, there would be a lot more interaction between channels. I wanted to demonstrate that it was possible to make a non inverting mixer with only 1 opamp. For the application I had in mind wide bandwidth wouldn't have been necessary ( D.C. control voltages in electronic music applications )

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