EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: funkimunky on October 22, 2012, 09:45:57 am
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I am learning to use the lm741 op amp but I cannot get any gain, in both the non inverting and inverting setup. I can get the signal to invert but the most I can get is about 1 to 1. I have the op amp powered by a switching benchtop power supply set at 18v and put through voltage divider (2x 100ohm) so I can get +9v 0v and -9v. The voltage divider has some 220uF caps to clean the signal. I am using a cheapo signal generator built for £5.00 powered by a 9v battery that outputs a sin wave of 500mV max. The output is connected to the non inverting input on the op amp while the ground is connected to the 0v rail of the voltage divider.
I have tried to adjust the power supply to see where the gain maxes out when it is the same as the input signal. This happens when the power supply is set at 4.4V or +2.2 -2.2.
Can anyone help me figure out why this is not working as I now have no Idea where to try.
I have attached a diagram of my setup.
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You're trying to drive a ten ohm load. Look at the resistor divider chain in the feedback loop. It takes a mighty powerful opamp to drive ten ohms with any appreciable gain. Change the ten ohms to 5K, change the other to 50K.
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you have it miswired, your just shorting the output through the 10 ohm, you want it on the other side of the 1K to the inverting input, to divide the voltage on that pin,
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(https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSuCygxNY9Vbq1kIC1iqF4wkOcZMxokVIwYlHh96zS0_Ymqdxbk)
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Thank you its all working as expected now. Its obvious now that you have shown me what the mistake was. ;D