Temperature measuring apparatus

DETAILED DESCRIPTION In the FIGURE, a positive power supply terminal 10 supplies power to a differential amplifier 12 and to a constant current generator generally designated as 14.
A terminal 16 is connected to ground potential 18 while a negative terminal 20 of the power supply is connected to supply power to a constant voltage supply means 22 as well as to a negative voltage input of the amplifier 12 and to a wiper 24 of a potentiometer having a resistance element 26.
Resistance element 26 is connected across appropriate terminals of the amplifier 12 to compensate for offset occurring in the 741 type amplifiers as produced.
These 741 amplifiers are produced by a plurality of manufacturers such as National and Fairchild.
Within constant current supply means 14, a zener diode 28 has its cathode connected to power supply 10 and its anode connected to a base of a PNP transistor generally designated as 30 having its emitter connected through a resistor 32 to power supply terminal 10.
A resistor 34 is connected between the base of transistor 30 and ground 18.
The collector of transistor 30 is connected to a junction point 36.
A capacitor 38 is connected between junction point 36 and ground 18 and is connected in parallel with a temperature sensing diode 40.
Diode 40 is inserted such that its direction of easy current flow is from junction point 36 to ground 18.
A resistor 42 is connected between junction point 36 and a junction point 44 which constitutes an input to the negative or inverting input of amplifier 12.
A resistor 46 is connected between junction point 44 and an output 48 of the constant voltage means 22.
Output 48 is further connected to a wiper of a potentiometer generally designated as 50 and connected at one end through a resistor 52 to ground 18 and at the other end through a resistor 54 to a junction point 56.
A transistor generally designated as 58 has its collector connected to junction point 56, its emitter connected through a resistor 60 to terminal 20 and its base connected through a resistor 62 to ground 18