Machine tool timer

Claim 1

A TIME CONTROL SYSTEM COMPRISING (A) AN A.C. ENERGIZING SOURCE, (B) AN A.C. MOTOR, (C) A SWITCH OPERATING TO INITIATE A TIME PERIOD, (D) A CONTROL REALY INCLUDING (1) AN OPERATING COIL, (2) NORMALLY OPEN PRIMARY RELAY CONTACTS ESTABLISHING AN ENERGIZING CIRCUIT BETWEEN SAID SOURCE AND SAID MOTOR ON OPERATION OF SAID RELAY, AND (3) NORMALLY OPEN SECONDARY RELAY CONTACTS ESTABLISHING A HOLDING CIRCUIT FOR SAID COIL FROM SAID SOURCE ON OPERATION OF SAID RELAY AND (E) AN ELECTRONIC TIMER CONNECTED IN SERIES WITH SAID SAID COIL AND SAID SWITCH AND FUNCTIONING TO EFFECT OPERATION OF SAID RELAY AT THE EXPIRATION OF A PREDETERMINED TIME PERIOD, SAID TIMER INCLUDING (1) A FULL-WAVE RECTIFYING BRIDGE CONNECTED THROUGH SAID SWITCH TO SAID SOURCE, (2) A HIGH IMPEDANCE CIRCUIT PATH CONNECTED BETWEEN OUTPUT TERMINALS OF SAID BRIDGE, SAID HIGH IMPEDANCE PATH INCLUDING (A) A TIMING CAPACITOR (I) CHARGING TOWARD THE VOLTAGES OF SAID BRIDGE ON OPERATION OF SAID SWITCH TO INITIATE A TIME PERIOD; (II) AT A RATE DETERMINED BY THE PARAMETERS OF SAID HIGH IMPEDANCE CIRCUIT, (3) A LOW IMPEDANCE CIRCUIT PATH CONNECTED BETWEEN SAID OUTPUT TERMINALS OF SAID BRIDGE, SAID LOW IMPEDANCE PATH INCLUDING (A) A CONTROLLED RECTIFIER HAVING (I) A GATING TERMINAL (4) A NEON TUBE CONNECTED BETWEEN THE HIGH VOLTAGE SIDE OF SAID CAPACITOR AN THE GATING TERMINAL OF SAID CONTROLLED RECTIFIER, SAID NEON TUBE (A) OPERATING TO TRIGGER SAID CONTROLLED RECTIFIER TO ITS CONDUCTING STATE WHEN THE VOLTAGE ACROSS SAID CAPACITOR EXCEEDS A THRESHOLD VOLTAGE ESTABLISHED BY SAID NEON TUBE, AND (5) A DISCHARGE PATH CONNECTED BETWEEN SAID CAPACITOR AND THE ANODE OF SAID CONTROLLED RECTIFIER TO SUPPLY HOLDING CURRENT FOR SAID CONTROLLED RECTIFIER, (F) WHEREBY SAID TIMER IS CONVERTED FROM A HIGH IMPEDANCE NETWORK TO A LOW IMPEDANCE NETWORK ON EXPIRATION OF SAID TIME PERIOD TO INCREASE THE ENERGIZATION LEVEL IN SAID COIL TO A LEVEL SUFFICIENT TO OPERATE SAID CONTROL RELAY.