MV^nSPS BEFORT 76^0 



The nonlinear! ty is due to the fact that the frequency varies as the 

 square root of the tension. For a frequency deviation of Vy^o, the 

 linearity can be held to within 3^ if "the tension deviates about 22^. 



Figure 6 shows the oscillator that induces vibrations in the wire. 

 The potentiometer in the feedback loop is adjusted for each Vibrotron^ 

 and the thermistor in the loop improves temperatiore -amplitude stability. 

 The circuit operates on 2^)- volts and draws h milliamperes . 



The specifications for the Vibrotron are : 



Repeatability: short term, 0.25^ 



Linearity: within +3^ of a straight line between end points 



Temperattire sensitivity: +0.1^ of bandwidth per C change of 



zero frequency 



SUI4I>a:NG AI4PLIFIER 



The amplifier shown in Fig. 7 combines and amplifies the soimd- 

 velocity, temperature, and pressvire signals so they may be transmitted 

 as a mixed frequency signal over the single-conductor cable. The 

 individual signal levels are adjusted by the 50,000-ohm potentiometers. 

 The complementary- symmetry push-pvill amplifier can furnish 6 volts, 

 peak-to-peak into an impedance of 50 ohms . 



IVECHMICAL PACKAGING 



The pressure case of the SVTP instrument is made of 504 stainless 

 steel tubing, l8 inches in length, 3-inGh inside diameter, and j/^-inch 

 wall thickness . The end caps are 1-inch thick and have 0-ring seals . 

 Sound -velocity, temperature, and pressure sensors are mounted with 

 0-ring seals in the lower cap. A bulldiead-type 2-conductor electrical- 

 signal output plug (Wo. X8l04-57 of the Joy Manufacturing Co., St. Louis, 

 Mo.) is compression mounted in the upper cap. 



The case has a computed static pressure crushing strength of 

 75,000 psi. All components of the SVTP instrument including transducers 

 have been pressure tested to 10,000 psi with no evidence of leaks. The 

 present output plug limits operation to oceanic pressures less than 

 10,000 psi, and a higher pressure output pltig should be used for pres- 

 sures above 5,000 psi. 



To permit recharging of the 7.2- and 2*1- volt nickel -cadraium batteries 

 without their removal from the case, gravity-actuated mercury sid-tches 

 have been installed that disconnect the batteries from the electronic 



15 



