| 摘要 |
An air-core gauge comprising two coils (X, Y) has a driving system with switches (Sc, Sx, Sy) on the junction terminal (Tc) and end terminals (Tx, Ty) of the two coils, and a drive circuit (D) controlling the switches so that each terminal is selectively at ground or +V, with one terminal being connected alternately to the two signal levels (ground, +V) with variable duty cycle depending upon the angle through which the pointer of the gauge is to be turned. For any given angle, one terminal is held at ground, another at +V and the third is alternated with appropriate duty cycle. Any angle of pointer deflection from 0 - 360 DEG can be achieved with just the two voltage levels (ground, +V) and calculating the duty cycle from an appropriate function of tan theta values for theta in the range 0 - 45 DEG . |
