The control unit contains four positive and negative 15 V dc power supplies, as 

 shown on DTNSRDC Drawing C- 508-1 in Appendix D. Power supply C provides power to 

 operational amplifier PI; the common lead is at a potential above ground equal to 

 the positive out of the Kepco power supply. Power supply B furnishes negative 30 V 

 to the depressor instrument housing via one lead and ground of the towcable. A 

 momentary depression of the CAL START switch parallel with the Zener diode causes a 

 5 V decrease in the negative 30 V output which starts the electrical calibration 

 sequence within the depressor instrument housing. The sequence is ZERO CHECK (ZC) , 

 CAL 1 (CI) , and CAL 2 (C2) . Power supply A provides power to all the operational 

 amplifiers denoted N&O and the common lead is connected to the depressor instrument 

 housing ground and isolated from the control unit ground. Power supply D supplies 

 power to the operational amplifier denoted by S and the common is tied to the 

 control unit ground. The control unit front panel contains four controls; an ON-OFF 

 power switch, a CAL START pushbutton switch, a RANGE SWITCH, and a RANGE VERNIER 

 10-turn potentiometer. The ON-OFF power switch controls the power to the four posi- 

 tive and negative power supplies in the control unit. The CAL-START switch is used 

 to start the electrical calibration sequence for the depth and flap measurements. 

 The RANGE SWITCH is used to set the desired depth of the depressor in 100-m incre- 

 ments. The RANGE VERNIER potentiometer allows for fine adjustment of the depressor 

 depth. Ten full turns of this control is equivalent to 105 m of depth; the smallest 

 increment on the dial is equivalent to 1/500 of full scale or 210 mm. 



The Kepco power supply provides the positive voltage to the depressor instru- 

 ment housing electronics. 



The Hewlett Packard Function Generator is incorporated into the system to dy- 

 namically control the depth of the depressor through a range of frequencies and 

 amplitudes. 



BASIN EVALUATION 

 Evaluations were conducted in the deep-water basin at DTNSRDC to examine towing 

 charactertistics of the depressor and operation of the control electronics. Evalua- 

 tions with active control were severely limited since the towcable length, by neces- 

 sity, was short and in no way representative of an operational configuration. There- 

 fore, depressor depth response to dynamic flap input could not be determined directly. 



17 



