A new recording wind vane

Abstract

New techniques applicable in the design of remote recording wind vanes are presented, and two preferred systems are described in detail. A small Duralumin vane is coupled to the shaft of a continuous rotation potentiometer, which may be a high resolution wire wound instrument, or constructed from a low-torque rotary switch. In one system the potentiometer has provision for alternative inputs, the supply voltage being automatically switched from one input to the other following a positional triggering action of the moving contact. Another technique utilizes a step potentiometer with one supply position, the sign of the output reference voltage being automatically changed as the wiper traverses the input connections. The outputs of the transducers change progressively over ranges of up to two revolutions of the shaft, and when range extremities are reached, revert to voltages which correspond to angular changes of 360°. The overlap provided prevents an incoherent recording which would otherwise be obtained when the moving contact reaches the ends of the track. A complete instrument weighs 350 g, has a vane 25 cm long and operates in winds down to 25 cm s−1 and the systems are well suited to automatic weather station operation.