The 12AU7 is a miniature medium-mu twin triode. This tube finds use as a phase-inverter/splitter in push-pull amplifier circuits in ac/dc radio equipment and in many diversified applications such as multivibrators or oscillators in industrial control devices. The tube is quite pokey and sections can even be connected in parallel to create a power amp with enough current to drive a pair of headphones or even a guitar speaker. A centre tapped heater permits operation of the tube from a 6.3V or a 12.6V heater supply. The tube requires a noval nine-contact socket and may be mounted in any position.