D.-c. clamp-on meter including a hall plate flux detector

Claim 1

A D.-C. AMMETER, COMPRISING IN COMBINATION, A HANDLE HAVING AN OPENING LENGTHWISE THERETHROUGH; A FIXED CLAMP HOLDER AFFIXED TO SAID HANDLE; A MOVEABLE CLAMP HOLDER, PIVOTALLY AFFIXED TO SAID HANDLE; THUMB ACTUATION PRESSURE MEANS ON SAID MOVEABLE CLAMP HOLDER ADAPTED WHEN PRESSED TO PIVOTALLY MOVE SAID CLAMP HOLDER TO AND AWAY FROM SAID FIXED CLAMP HOLDER; SPRING MEANS TENDING TO MAINTAIN SAID MOVEABLE CLAMP HOLDER TOWARDS SAID FIXED CLAMP HOLDER; INNER AND OUTER MAGNETIC POLE PIECES HELD BY SAID FIXED CLAMP HOLDER, BOTH HAVING ARCUATE POLE FACES ADAPTED TO PARTIALLY ENCIRCLE A CABLE, THE OUTER FIXED POLE PIECE INCLUDING ONE MEMBER OF A PAIR OF INTERLEAVING MATING MEMBERS; A PIVOTING MAGNETIC POLE PIECE HAVING AN ARCUATE SHAPED FACE COOPERATING WITH SAID FIXED POLE PIECES ARCUATE FACES SO AS TO ENCIRCLE A CABLE BETWEEN AN SAID FACES, AND HAVING THE OTHER MEMBER OF SAID PAIR OF INTERLEAVING MATING MEMBERS; A RECTANGULAR HALL CRYSTAL DISPOSED BETWEEN SAID INNER AND OUTER FIXED POLE FACES SO THAT ONE EDGE THEREOF IS PARALLEL TO A CABLE ENCIRCLED BY SAID POLE FACES, SAID HALL CRYSTAL HAVING OUTPUT LEADS; HALL CRYSTAL EXCITATION LEADS PASSING THROUGH SAID HANDLE OPENING TO OPPOSED SIDES OF SAID CRYSTAL SO AS TO SEND A HALL EXCITATION CURRENT THERETHROUGH AT RIGHT ANGLES TO THE MAGNETIC FIELD CREATED BY A CURRENT CARRYING CABLE ENCIRCLED BY SAID POLE FACES; WHEREBY WHEN AN EXCITATION CURRENT SOURCE FEEDS AN EXCITATION CURRENT THROUGH SAID HALL CRYSTAL, THE MAGNETIC FIELD CREATED BY A CURRENT CARRYING CABLE ENCIRCLED BY SAID POLE FACES WILL CAUSE A MEASUREABLE HALL VOLTAGE DROP ACROSS SAID CRYSTAL AT RIGHT ANGLES TO SAID EXCITATION CURRENT AND SAID MAGNETIC FIELD TO PROVIDE A SIGNAL IN SAID OUTPUT LEADS, CORRESPONDING TO THE MAGNITUDE OF THE D.-C. CURRENT PASSING THROUGH SAID CABLE.