DickCappels
- Joined Aug 21, 2008
- 10,180
Get rid of the second amplifier - it is running open loop (Analogkid pointed this out already) and it cannot work as an amplifier that way. Just double the feedback resistor and you are done.
The LM324 can operate with its input at ground but in order for the output to run lower than a few tens of millivolts, you need to put a resistor from the output to ground -1K should work fine for your application.
By the way, an LM324 has four opamps in the 14 pin package. In the original document, the inverting input (pin 2) was mistakenly marked as "+".
You might want to spend some time admiring the datasheet.
http://www.google.co.th/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CEYQFjAB&url=http%3A%2F%2Fwww.ti.com%2Flit%2Fds%2Fsymlink%2Flm124-n.pdf&ei=vbQcU_n1NczarAePt4Eg&usg=AFQjCNEOyKTccifkq6d6zR_PLC30n98XpA&sig2=94Yq4j342gkl7zojaW3PUg&bvm=bv.62578216,d.bmk
The LM324 can operate with its input at ground but in order for the output to run lower than a few tens of millivolts, you need to put a resistor from the output to ground -1K should work fine for your application.
By the way, an LM324 has four opamps in the 14 pin package. In the original document, the inverting input (pin 2) was mistakenly marked as "+".
You might want to spend some time admiring the datasheet.
http://www.google.co.th/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CEYQFjAB&url=http%3A%2F%2Fwww.ti.com%2Flit%2Fds%2Fsymlink%2Flm124-n.pdf&ei=vbQcU_n1NczarAePt4Eg&usg=AFQjCNEOyKTccifkq6d6zR_PLC30n98XpA&sig2=94Yq4j342gkl7zojaW3PUg&bvm=bv.62578216,d.bmk
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