Characteristics adjusting apparatus of physical quantity sensing device and a thermal type air flow measuring instrument, and associated adjusting method

A thermal type air flow measuring instrument comprising at least one heating resistor arranged in an auxiliary passage through which part of air flowing through an air intake passage of an internal combustion engine flows;

• and an electronic circuit for controlling heating temperature of said heating resistor and for outputting a signal corresponding to a flow rate of air flowing through the air intake passage based on a quantity of heat radiated from the heating resistor to the air, which comprises an output characteristic adjusting circuit for adjusting output characteristic or a control adjusting circuit for adjusting a heating state of said heating resistor provided in said electronic circuit and a housing containing therein said electronic circuit, and which further comprises, outside said housing, an adjusting terminal electrically connected to said adjusting circuit for transmitting an electric signal to said adjusting circuit;
• and at least one of:
• an output terminal connecting said electronic circuit and external devices for transmitting an output signal of said electronic circuit, a power source terminal connected to an power source, and a ground terminal electrically connected to the ground;
• and wherein said adjusting terminal and said connector terminal are positioned outside the air intake passage when said housing its inserted through and fixed to a hole provided on the wall surface of said air intake passage so that said auxiliary passage is positioned in the air intake passage.