Abstract: An analog voltage to duty cycle converter is provided using a series connected resistor and capacitor. The capacitor is charged in one direction through the resistor from the difference between the analog voltage and a reference voltage maintained across a zener diode by one polarity of output from a differential amplifier responding to the charge across the capacitor. When the charge across the capacitor reaches the difference necessary to cause the differential amplifier to change the polarity of its output, a positive feedback firmly toggles the output to the other polarity and the capacitor is allowed to charge in the opposite direction due to cut-off of the zener current by a diode in the amplifier output circuit. The capacitor then charges in an opposite direction due to the analog voltage alone and the reference voltage again switches "on" when the amplifier output goes positive. The duty cycle is then proportional to the analog voltage.

Abstract: A multipoint recorder having a counter for producing sequential address signals for sequential selection by randomly addressable input switching means and recording by randomly addressable recording means. A randomly addressable visual display indicating the point being recorded is also connected to the common bus output of the counter. This provides a recorder in which no circuit or mechanical means is required solely to provide synchronization of the input switching means, the recording means and the visual display.