The HD9008TR and HD9009TR are single block RH and temperature microprocessor transmitters.
The HD9008TR is a passive transmitter with a 4…20mA output and 7…30V DC power supply.
The HD9009TR is a transmitter with a 0…1V standard voltage output (other outputs available on demand) and 7…30V DC power supply.
Sensors are mounted at the end of a plastic tube: a capacitive humidity sensor and a platinum temperature sensor (100O @0 °C).
These instruments can be reprogrammed by means of a key, no jumper or potentiometer actions are required.
The humidity sensor is a condenser which dielectric is made with an hygroscopic polymer. As water dielectric constant is approximately 80, you’ll get a strong change in capacity as the humidity content of this polymer changes.
The advantages of this kind of sensor are: good linearity, insensitivity to temperature changes, fast response time and long-lasting life.
