CENTRAL SCIENTIFIC CO., CHICAGO, U. 8. A. 



225 



Nos. 4972-8. 



RHEOSTATS, Dodge Design, providing a system of wiring whereby a Cenco Rheostat may be con- 

 nected either in series with the load or as a shunt across the line, the change being made simply 

 by closing a single-throw switch. By means of the slider, the resistance may be varied from 

 zero to the maximum of the rheostat. When connected in series with the load, this variation 

 of the resistances produces a variation in the voltage across the load, the minimum of which is 

 limited by the ratio of the load resistance to the total resistance of the circuit. The current 

 through the load is varied in the same proportion. By this connection it is impossible to obtain 

 very small currents and voltages. By closing the switch and thereby shunting the rheostat 

 across the line, a potentiometer effect is secured by means of which the voltage and current 

 may be varied from zero to a maximum amount, which is the same as the minimum of the series 

 connection. In this manner one secures the full value of the rheostat and in a simple fashion 

 can run the entire range of voltage and current. 



OTHER ADVANTAGES OFFERED BY THE DODGE RHEOSTAT. 

 1 Substantial mounting upon base of asbestos slate. 

 2 Clear distinction between terminals of load and line. 



3 Rating of rheostat in maximum current and voltage stamped in plain figures on slider. 

 4 High efficiency. Greatest possible current range for given voltage and size of tube. 

 5 Easy selection of proper capacity. Voltage of source and maximum load current determine the 



particular rheostat to purchase. 



In ordering rheostats of the Dodge design it is necessary to consider only the available voltage 

 and the maximum current required by the load. Those listed first under each catalog number 

 are designed to give the very highest capacity possible within the limits imposed by voltage, 

 length of tube, and a moderate temperature rise, and therefore have the lowest resistance. 

 These rheostats should be ordered unless it is absolutely certain that a higher resistance is 

 needed. For these cases the other sizes are provided, wound with smaller wire, and hence of 

 smaller current carrying capacity. Current rating is for continuous service with moderate tem- 

 perature rise. Overloads of 50 per cent, and more are permissible on intermittent service. 

 4972. RHEOSTATS, Dodge Design, Single. For a maximum voltage of 40. Length of tube, 12 inches. 



No 12 6 4 



Maximum current, amperes 6 3 2 



Approximate resistance, ohms 10 40 90 



Each $12.50 12.50 12.50 



4974. RHEOSTATS, Dodge Design, Single. For a maximum voltage of 110. Length of tube, 12 inches. 



No 5 4 3 



Maximum current, amperes 2.5 2.0 1.5 



Approximate resistance, ohms 65 90 175 



Each 12.50 12.50 12.50 



4976. RHEOSTATS, Dodge Design, Single. For maximum voltage of 110. Length of tube, 20 inches. 



No 8 6 



Maximum current, amperes 4 3 



Approximate resistance, ohms 35 75 



Each 16.00 16.00 



4978. RHEOSTATS, Dodge Design, Single. For a maximum voltage of 220. Length of tube, 20 inches. 



No 4 3 



Maximum current, amperes 2 1.5 



Approximate resistance, ohms 160 315 



Each 16.00 16.00 



4980. RHEOSTATS, Dodge Design, Double. Two tubes in parallel on one base. 



No A B C D 



Maximum voltage 40 110 110 220 



Maximum current, amperes ." 12 5 8 4 



Approximate resistance, ohms 32 17 80 



Length of tube, inches 12 12 20 20 



Each 22.00 22.00 27.50 27.50 



