Remote portable load indicator for power presses and the like

Claim 1

APPARATUS FOR INDICATING THE PEAK VALUE OF THE STRAIN ON A MACHINE MEMBER COMPRISING AT LEAST ONE STRAIN GAGE MOUNTED ON SAID MEMBER AND A PORTABLE APPARATUS FOR CONNECTION TO SAID STRAIN GAGE FOR MEASURING OF ITS PEAK RESISTANCE, SAID PORTABLE APPARATUS INCLUDING A BATTERY CONNECTABLE IN A CLOSED CIRCUIT WITH SAID STRAIN GAGE TO DEVELOP A CURRENT THERETHROUGH OF AMPLITUDE DETERMINED BY THE INSTANTANEOUS RESISTANCE OF THE GAGE, A FIRST AND A SECOND DIRECT CURRENT AMPLIFIER EACH OF AMPLIFICATION TOO LOW FOR BUILDING UP CURRENT CHANGES THROUGH SAID GAGE TO A LEVEL SUITABLE FOR INDICATION BUT OF CASCADED GAIN SATISFACTORY THEREFOR, AND EACH AMPLIFIER BEING SUBJECT TO LONG-TERM DRIFT, SAID FIRST AMPLIFIER BEING DIRECTLY CONNECTED TO SAID GAGE TO MEASURE THE INSTANTANEOUS CURRENT THERETHROUGH, THE OUTPUT OF SAID AMPLIFIER BEING CAPACITIVELY CONNECTED TO THE INPUT OF SAID SECOND AMPLIFIER TO MINIMIZE THE EFFECTS OF LONG-TERM DRIFT OF THE FIRST AMPLIFIER, AND AN R-C CIRCUIT INCLUDING THE SERIES COMBINATION OF A FIRST CAPACITOR, A RECTIFIER AND A SECOND CAPACITOR CONNECTED ACROSS THE OUTPUT OF SAID SECOND AMPLIFIER, THE CAPACITANCE OF SAID FIRST CAPACITOR BEING MAY TIMES HIGHER THAN THE CAPACITANCE OF SAID SECOND CAPACITOR SO THAT VOLTAGES REPRESENTING PEAK STRAINS ARE TRANSFERRED FROM THE SECOND AMPLIFIER THROUGH SAID FIRST CAPACITOR INTO SAID SECOND CAPACITOR FOR STORAGE THEREBY, AND MEANS FOR INDICATING THE VOLTAGE ACROSS SAID SECOND CAPACITOR.