I've been working with an old book by Yannis Tsividis "A First Lab in Circuits and Electronics" published by John Wiley & Sons some time ago. No date given. While working on one of the Op Amp exercises I set up the following circuit using an LM741. I added a 560Ω load resistor to the output and the needed rail capacitors. I used my dual individual power supplies connected to provide +/- 5V to the rails but the -5V drifted to -5.03V even when intially set to 5.04V it supplied -5.0V at the rail.
I set the Vref to 2.50V on pin 2 and ran the voltage to pin 3 up and down. And was surprised that the closeness to the positive and negative supply rails was different. So I pulled up the LM741 PDF from Fairchild up and looked for what the Voltage offset from the rail should be.
That is for +/-15V but 14V/15V*100% tells me it should only be a ~7% offset. But the numbers I was getting didn't support that. I knew I had 2 different lots of 741s and I was seeing 2 different sets of outputs so I tried the 2 TI uA741CPs from DK and got a 3rd unique set of values. The TI chips gave me a 12% offset on the + rail and ~38% offset on the - rail.
So my question is, how much offset from rail should there be? And, Is there a parameter on the PDF that I am missing?
I set the Vref to 2.50V on pin 2 and ran the voltage to pin 3 up and down. And was surprised that the closeness to the positive and negative supply rails was different. So I pulled up the LM741 PDF from Fairchild up and looked for what the Voltage offset from the rail should be.
That is for +/-15V but 14V/15V*100% tells me it should only be a ~7% offset. But the numbers I was getting didn't support that. I knew I had 2 different lots of 741s and I was seeing 2 different sets of outputs so I tried the 2 TI uA741CPs from DK and got a 3rd unique set of values. The TI chips gave me a 12% offset on the + rail and ~38% offset on the - rail.
So my question is, how much offset from rail should there be? And, Is there a parameter on the PDF that I am missing?
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