| 摘要 |
1530123 Analogue to digital converter; pulse frequency modulator LUCAS ELECTRICAL Ltd 21 Oct 1975 [1 Nov 1974] 47295/74 Headings H3H and H4L Analogue voltage inputs to either or both inputs 111,110 vary the frequency of pulse train output of bi-stable 121, subsequently converted to digital by counter 135. An input voltage applied to 110 charges capacitor 120 via potential divider 113, 114 and op. amp. 118 to the voltage level on 111 detected at comparator 122. Bi-stable 121 changes state causing transistor 115 to conduct and the input to discharge capacitor 120 via potential divider 116, 117 and resistor 119 to a preset level detected at comparator 123. The frequency of the pulse train is thus dependent on the sawtooth shape (due to 110) and amplitude (due to 111). The pulse train is counted in 135 for a period due to input 139, which may derive from a further analogue input. The analogue inputs may be due to engine speed, manifold pressure or airflow &c. |
