Somewhat of a technical question: every op amp tutorial always talks about how both inverting and non-inverting pins are at the same voltage and the op amp itself works to ensure that. I get that they are always talking about ideal op amps and real will differ a bit. I've been working with typical dual op amps. Every op amp OD/distortion circuit that I build when set up in a non-inverting configuration with Vref = 1/2 VCC and a bias resistor on the + pin always measures around 0.1 - 0.5 V lower than my output and inverting pins measure (which are only 0.001 V different). The non inverting pin is always a good bit less than Vref, and approaches Vref as I reduce the bias resistor size (values between 2 M and 470k). I even measured some of my assembled OD pedals and observe the same behavior. What's going on here? Is the current into pin 3 really that high that would cause that kind of voltage drop across a 470k bias resistor?
Another related question: if my pin 3 measures 4.3 VDC and pin 2 measures 5 VDC and my gain is 100, why doesn't the op amp drive to the positive rail? 100*(5-4.3)=70. Really trying to understand this stuff and can't find any resource that addresses these questions. Thanks!
Another related question: if my pin 3 measures 4.3 VDC and pin 2 measures 5 VDC and my gain is 100, why doesn't the op amp drive to the positive rail? 100*(5-4.3)=70. Really trying to understand this stuff and can't find any resource that addresses these questions. Thanks!