Circuitry for sequentially energizing first and second load devices from a direct current source, comprising:
- a first relay coil (K-1) electrically associated with the first load device, and a second relay coil (K-2) electrically associated with the second load device;
- first power contacts (22a) controlled by said coil (K-1) connecting the first load device to the current source only when said first coil (K-1) is energized;
- second power contacts (22b) controlled by said second coil (K-2) connecting the second load device to the current source only when said second coil (K-2) is energized;
- means for energizing the first relay coil comprising a first capacitor (C-1) having one of its leads normally connected to ground at 38 and its other lead connected to the first relay coil, a first interruptable high resistance path including a switch (33) (34) (35) connecting the current source to the other capacitor lead only when the first relay coil is de-energized whereby the first capacitor is charged without operating the coil, a first interruptable low resistance path including a switch (40) (39) connected to the current source, and cycle-initiating switch means (P.S.) operable to disconnect the ground and connect said one capacitor lead to said low resistance path whereby a relatively large voltage is then impressed on said one capacitor lead to thus cause the capacitor to energize the first relay coil (K-1);
- means for energizing the second relay coil (K-2) comprising a second capacitor (C-2) having one of its leads connected to ground through relay contacts (24a) only when relay coil (K-1) is energized, said second capacitor having its other lead connected to the second relay coil (K-2), a second interruptable high resistance path including a switch (33) (43) (45) supplying current from the aforementioned source to said other lead of the second capacitor only when the first relay coil (K-1) is energized, a second interruptable low resistance current path including a switch (33) (34) (46) connecting the current source to said one lead of the second capacitor only when the first relay coil is de-energized, a timer switch (S-1) operable to de-energize said first relay coil (K-1) and thereby enable a relatively large voltage to be impressed through the second low resistance path onto said one lead of the second capacitor, whereby that capacitor energizes the second coil.