GAGE PACKAGES 



Figure 16 details the electrical circuitry of a modular 

 package for measuring temperature. The temperature sensor 

 consists of a pair of thermistors which control the frequency 

 of a Wien-bridge oscillator. Tests have shown that, with 

 suitable padding resistors, the frequency can be made a 

 linear function of the temperature. Typically, the oscillator 

 frequency may be made to vary from 6000 cycles per second 

 at 0° C to 12,000 cycles per second at 30°C„ In this way, 

 by means of a shipboard counter and timer, direct digital 

 readout of temperature may be obtained. 



Figure 16 shows also the seven "bit" circuits which 

 decode the control signal. Each bit circuit has two 

 outputs of opposite polarity. The polarities are interchanged 

 when the primary winding of the transformer is caused by the 

 control signal to carry current. The binary number identi- 

 fying a package is determined by the seven binary choices 

 involved in connecting one of the two outputs (A or A , 

 B or -B, etc) of each of its seven bit circuits into the 

 7-input "and" circuit. The carrier oscillator, the frequency 

 of which is controlled by the measured temperature or 

 pressure, will be turned on only if all seven inputs to the 

 "and" gate are of the proper (same) polarity. Thus, each of 

 128 different packages can be interrogated separately by 

 the proper combination of the presence or absence of exciting 



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