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2013-08-31 11:54 6001894 Anonymous (ss.png 216x123 4kB)
i want to try some stuff with op amps (LM324) but only have one 9V battery. normally you have +Vcc and -Vcc,but is it possible to run them with 9V and GND without having any disadvantage? pic related, some kind of single supply circuit i found

4 min later 6001906 Anonymous
simple, just set up a voltage divider with two resistors to get 4.5V, this serves as your ground, with the battery +4.5 and -4.5 off this respectively

18 min later 6001928 Anonymous
but wouldn't i have to invert the voltage to get -4.5V?

9 hours later 6002775 Anonymous (opamp.png 610x392 17kB)
you font need -Vcc. The only thing it restricts is what you can have for output and what voltages can be applied to the op-amp. Here is a simplified equivalent model of the op-amp

10 hours later 6002798 Anonymous
>>6001928 -4.5V is a difference of potentials. It's -4.5V with respect to the ground. so basically, you put two resistors between the two poles of your battery, and a wire in between those resistors will be the ground; the - side will be at -4.5 and the + side will be at 4.5V :)

10 hours later 6002813 Anonymous
It depends on the opamp. Some are designed for single rail operation, some require positive and negative power rails to function properly.

24 hours later 6003760 Anonymous
There isn't really such a thing as negative voltage

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