Hello all I've been working on a simple voltage follower circuit that will be used to protect an analog output on a data acquisition/output board that is connected to a computer. The voltage follower will go between the analog output and will drive a single LED. I planned to vary the outputted voltage to vary the current that goes through the LED. Even though this circuit is really simple, it hasn't been behaving as it should. Two problems I've had with it are: The Op amp is still drawing current from the source, even though it should have a nearly infinite input impedance. The current it draws from the source is about the same amount of current that the LED is receiving. What gives? This problem has been super frustrating because it should be so simple. I've tried building the circuit in different ways and am not sure if I've fried something or not. I've attached my schematic. The op amp is powered by one 9V battery. The input can go from +10 to -10v, though I'm basically planning to use in the 3-4V range. Thanks!