APT 1000 series transducers are a kind of direct electro-pneumatic conversion unit which can change different current signals into corresponding output pneumatic signals. The pneumatic power amplifier inside the transducer can obtain pneumatic signals of high output power to increase the work speed of various pneumatic actuators. In addition to the conversion unit between electric meter and pneumatic controller or pneumatic valve, it can also be applied with the pneumatic-pneumatic valve positioned to achieve the function of electro-pneumatic valve positioners. APT1000 series transducer converts electric signal to a pneumatic output which can be used to many different operates, such as valve, valve actuators, air cylinders, liquid or gas systems etcs.