In the simplest electronic terms, a voltage amplifier is any amplifier that creates a voltage output higher than the input voltage originally fed through the amplifier. This is different from a power amplifier, which creates a more powerful output than the original signal strength fed into the amplifier. A voltage amplifier is used when the transmittal of a higher voltage across a longer wire or larger area is necessary, and it is similar to a transformer in the sense that it can increase voltage output. A voltage amplifier can be thought of like a hose nozzle — the amount of water flowing in the hose is amplified in strength coming out of the nozzle.
A voltage amplifier does not supply power, but merely increases the amount of power coming through a given circuit in order to obtain a desired result. These amplifliers are typically not suitable for powering devices such as motors, but rather are intended to increase the amount of available voltage to assist in reading signals from various controls or other items. For example, a low voltage sensor that might read the level of oxygen in the exhaust of a vehicle or the amount of torque coming from an electronic motor might need a voltage amplifier to receive enough voltage to properly measure the signal it is supposed to be receiving.
Creating a voltage amplifier circuit is fairly simple, and generally requires only two resistors and an operational amplifier. Combining these will create a simple amplifier that can potentially perform a number of tasks. There are several different types of voltage amplifiers, including inverting and non-inverting amplifiers, which can either reverse the natural sine wave of the incoming current or not reverse it, depending on the desired output. There are also voltage amplifiers, known as voltage difference amplifiers, and they can amplify the difference in voltages in a circuit so that this differing voltage output can be read and analyzed.
It is important to fully understand what outcome an individual is attempting to get with a voltage amplifier. This must be done before deciding which type one is right. Once an individual has designed his electrical circuit for the proper amount of output and input voltage, he will be able to determine what voltage amplification, if any, is necessary to make his electronic devices operate properly.