Monitor control circuit

Claim 1

A MONITOR CONTROL CIRCUIT FOR AN EVENT RECORDER WHEREIN EVENTS ARE RECORDED ON A MOVING ELECTROSENSITIVE PAPER CHART BY A WRITING CIRCUIT SUPPLYING VOLTAGE PULSES TO A CONDUCTIVE STYLUS IN CONTACT WITH SAID PAPER AND WHEREIN WRITING IS PREVENTED BY EFFECTIVELY SHORT CIRCUITING THE SECONDARY OF A CONTROL TRANSFORMER HAVING A PRIMARY SHUNTED ACROSS SAID WRITING CIRCUIT, COMPRISING A COMPARATOR OSCILLATOR INCLUDING A BLOCKING OSCILLATOR HAVING A FEEDBACK LOOP WHEREIN FEEDBACK IS NEGATIVE WHEN A PRESET TRIP VOLTAGE EXCEEDS AN INPUT SIGNAL VOLTAGE, AND POSITIVE WHEN THE INPUT SIGNAL VOLTAGE EXCEEDS THE TRIP VOLTAGE WHEREBY SAID BLOCKING OSCILLATOR GOES INTO OSCILLATION, A SENSING CIRCUIT RESPONSIVE TO SAID OSCILLATIONS, A LOW FREQUENCY MULTIVIBRATOR CONTROLLED BY SAID SENSING CIRCUIT, A GATE CONTROL CIRCUIT RECEIVING THE OUTPUT OF SAID MULTIVIBRATOR AND CAUSED THEREBY TO OPEN CIRCUIT INTERMITTENTLY THE SECONDARY WINDING OF SAID CONTROL TRANSFORMER WHEREBY SAID STYLUS WRITES A DOTTED LINES, AND MEANS CAUSING SAID GATE CONTROL CIRCUIT TO OPEN CIRCUIT CONTINUOUSLY THE SECONDARY WINDING OF SAID CONTROL TRANSFORMER WHEN THE INPUT SIGNAL VOLTAGE ATTAINS A HIGH LEVEL WHEREBY SAID STYLUS WRITES A SOLID LINE.