CIRCUIT FOR CONTROLLABLY DRIVING A SCHMITT TRIGGER IN RESPONSE TO PRESELECTED VARIATIONS IN AN ANALOG INPUT SIGNAL AND IN A DIGITALIZED INPUT SIGNAL

摘要

A circuit is disclosed for controllably driving a Schmitt trigger in response to variations in both an analog and a digitalized input signal. A Schmitt trigger normally comprises a pair of electronic devices, each of the devices having a control electrode. The circuit of the present invention applies the analog signal to one of the control electrodes and applies the digitalized signal to the other of the control electrodes. The control electrodes of the Schmitt trigger are biased by voltage divider means so that the electronic device whose electrode is receiving the analog signal is normally in the nonconducting or "off" condition while the electronic device receiving the digitalized information is normally in the conducting or "on" condition. A portion of the digitalized signal is derived by suitable switching means from the input analog signal.