# about power supply of opertional amplifier

I am constructing an operational amplifier as shown in the following figure. I use a batter as supplier for the OP Amp and set it up as a non-inverting amp circuit. I saw that the output was clipped while I feed it with a sine at about 1kHz. I wonder if there is any thing to do with the power supplier, what supplier should I use if so.

p.s. the intpu signal is of sine form, the peak-to-peak voltage is about 650mV, the frequency is about 1KHz or less

• What's the actual input voltage of the sine wave? Also what's the output load? Commented Aug 27, 2013 at 21:51
• You need to put a Vcc/2 bias on the noninverting pin, and eliminate the amplifier's DC gain. Also, the TL08x is a horrible choice for a 9V single supply. Look for a CMOS rail to rail op amp such as the TLC2272, LM7322, or LMC6462. Commented Aug 27, 2013 at 21:52
• I think the TL081 designation comes from the default component labels in CircuitLab -- I would verify what opamp the OP is really using. For some component types, CircuitLab allows you to change the part number; for others, it doesn't, which can be quite confusing! Commented Aug 28, 2013 at 5:11

The gain of the circuit is +11 (Gain = 1 + $\frac{R_F}{R_1}$). This means when the input sinewave is positive 0.1V you'd expect an output that is +1.1V and when the input is negative 0.1V you'd expect an output that is -1.1V. These numbers are all relative to ground. The first problem is that your op-amp has supplies that are +9V and 0V so immediately it's clear that the op-amp can't produce the -1.1V or indeed any negative voltages.
What to do? Both the input signal and the ground connection of $R_1$ need to be set to halfway between 9V and 0V - at the moment you're throwing darts at a board that is 2 foot higher than you thought - you are just hitting "three" when you should be aiming for bullseye (sorry about the darts analogy but it seems apt!).
OK, so the problem is that your input AC signal is 0V (or ground) referenced - if you just wish to amplify AC signals then you can use a capacitor (that blocks the steady 0V connection) and then have a resistor divider that sets midrail on the input at 4.5V. You have to do the same for $R_1$ - I would make R1 2 x 200ohm resistors; one going to +9V and one going to 0V and joined together at the -Vin input.