Control circuit with microcomputer capacitor charge control - provides digital adjustment of pulse frequency and duty cycle

摘要

The electronic control circuit has a capacitor (C1) which is charged up by digital impulses and discharged via a resistance dependent on an analogue physical parameter. The charge condition of the capacitor stands in equilibrium between the charge and discharge processes and is fed to a threshold switch (SW) used to trigger the control process, e.g. using a microcomputer. The frequency and duty cycle of the digital pulses controlling the charging transistor (T) can be adjusted in purely digital fashion. This is achieved by feeding the digital charging pulses to the capacitor directly through a microcomputer. The microcomputer has one output providing charging pulses directly to the control circuit to be fed to the capacitor via a resistor (R1). The threshold switch is driven by a low-pass filter (R2,C2).