nikongod
DIY-ku
- Joined
- Jan 24, 2005
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Quote:
If using the OPA551 opamp, why doesn't the (-) input (pin 2) need to be connected to ground? Pete Millett just mentioned putting it in the feedback loop by connecting it to pin 6.
The op amp compares the 2 inputs and tries very hard to make them equal.
When you connect the - input to the output the op amp tries to make the voltage on the output (which is hooked up to the - input) equal to the + input which gives you a buffer.
When you ground the - input and apply signal to the + input the op amp applies full gain to the signal on the + input and bad things usually happen. Full gain on the opa551=100dB=voltage gain ~10000.
http://en.wikipedia.org/wiki/Operational_amplifier