Needle Valve Controller

The main component is an Eurotherm 2216e configured as a motorized valve controller. The box contains also a bipolar power supply used for the the pressure sensor and a network of resistors and diodes for the asymmetric power supply of the DC motor. The motor current is limited to 40/50 mA for closing/opening and may be reduced by means of a resistor in the motor box.

There is an upper end switch touched when the valve is sufficiently open, but there is no lower end switch. The motor is rated in a way that it does not damage when blocked.