Simple Inverting amplifier example. Amplify the input signal -5 times. To amplify more, replace the 75 k and 15k Ohms resistors, to a larger ratio. Example replace 15k with a 1.5k and you'll get a ratio of 50 times amplification, but will saturate the output. The +15 V and -15 V, are the operating linear range forma this model.
