Help in volt amplifying

renaissances21 said:

Hi I had build my own cct but the signal and waveform I get was very small.So I intend to rebuild another cct,(pls refer to my pic name as propose cct),can anyone advise me on the op-amp to use and the resistors values to use,so I can make my signal and waveform big as compare to my current one.Thks



(pic/photo) http://community.webshots.com/user/renaissances07

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Nigel Goodwin said:

renaissances21 said:

Hi I had build my own cct but the signal and waveform I get was very small.So I intend to rebuild another cct,(pls refer to my pic name as propose cct),can anyone advise me on the op-amp to use and the resistors values to use,so I can make my signal and waveform big as compare to my current one.Thks



(pic/photo) http://community.webshots.com/user/renaissances07

Click to expand...

You proposed circuit is an inverting amplifier, so the output will be inverted - is that what you want?.

Your original circuit is far too blurred to read, but the second stage looks to be a similar inverting amplifier?, why not just change the feedback resistor in that and increase it's gain?.

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renaissances21 said:

I didn't know that the output will be inverter. So how do I use a feeback resistor?? PLs enlighten me. U mean in my propose ciruit, as a feedback resistor? Can you show me the circuit? and what value should I use for all the resistors in my circuit? and what type of op-amp should I use? I really poor in all this,so pls really advise me.Many thanks

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