Toggle switch/indicator circuit

Claim 1

Switching apparatus comprising in combination: a. a double-pole double-throw push-button switch having a pair of normally closed and normally open contacts; b. an indicator lamp located in close proximity to said push-button switch; c. first and second transition edge-triggered flip-flops of the type having a Clear input terminal, a Set input terminal, a Data input terminal and an Enable input terminal and first and second complementary output terminals; d. means connecting one of said pair of normally closed and normally open contacts individually to said Clear input terminal and said Set input terminal of said first flip-flop respectively and the other of said pair of normally closed and normally open contacts to a common point of fixed potential; e. means connecting said first output terminal of said first flip-flop to said Enable input terminal of said second flip-flop; f. means connecting said indicator lamp in series circuit between a source of positive potential and said Data input terminal of said second flip-flop; and g. means connecting said second output terminal of said second flip-flop back to the Data input terminal of said second flip-flop, the arrangement being such that the first momentary closure of said normally open contacts sets said first flip-flop and enables the toggling of said second flip-flop from its present binary state to its opposite binary state, said indicator lamp being illuminated only when said second flip-flop is in a predetermined one of its two possible states.