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Electronics => Electronics => Topic started by: aruna1 on June 28, 2011, 05:36:36 AM

Title: summing amplifire resistor selection
Post by: aruna1 on June 28, 2011, 05:36:36 AM

hi
I'm making a non inverting summing amplifier using LM324. I will be adding 5V inputs (supplied using micro controller pins to get voltages 5,10,15,20 from summer) since all the resistor values are equal, is there any procedure to select a proper resistor value ? see the attachment
thank you.

Title: Re: summing amplifire resistor selection
Post by: TrickyNekro on June 28, 2011, 06:35:57 AM

Every op amp has a very small but existing biasing current. Keep that in mind when selecting resistors for op amps generally.
So taking that into consideration, you select feedback resistors accordingly.

But yes, if you don't have any extreme power consumption requirements the 10 - 100 kOhm range usually works with most op amps