Patent GB-1252632-A (GB)
IPC: B60R16/02
Filed: 1969-03-10
Abstract: 1,252,632. Selective control and indication. MOTOROLA Inc. 10 March, 1969 [1 April, 1968], No. 12390/69. Heading G4H.  A power distribution and control system for a car comprises a power source 20 supplying pulsating power 21A, Fig. 1, a number of stations arranged in sets, all stations in a set having the same address, and each set including a control station and a receiver station with a device to be operated, a single power line and a signal distribution line serving all the stations, a master sequencing circuit supplying a start pulse to the signal line, address means at each station responsive to the start pulse and having means responsive to one pulse of the power voltage 21A (a different pulse for each of the sets of stations) to switch both the control station and the receiver station to the signal line, the control station in each set being operative when connected to the signal line to apply a control signal to the signal line, the receiver station in each set being adapted to receive the control signal and responsive to it to perform a corresponding function. Power source 20 may be a transistor square-wave generator having a frequency of 400 cycles/sec. Sequencer 22 repetitively supplies address signal sets consisting of a negative start signal and 40 positive pulses. Each station counts a predetermined number of power pulses after the start signal. Fig. 3 shows an arrangement for controlling lamps 44 from console 35. The counters 40 and 40A both count 12 pulses and open associated gates 41, 41A. The control circuit 45 generates a control pulse which at the twelfth pulse of the series passes on to line 23 and through the gate 41A to circuit 42 which applies a signal to storage 43 switching on the lamps 44. A number of pairs of stations are grouped together in sets for the purpose of control or indication e.g. fuel level. Counters 40 and 40A are reset via diodes 46 by the start pulse which is negative and at least twice the magnitude of the signal pulses. A control station such as 28 may control more than one receiver station 29. A number of stations having different addresses may use the same counter, gates being opened at different counts. In another form the cycle of 40 pulses is replaced by a cycle of 7 pulses 71, Fig. 6, of different amplitudes. This is provided by a circuit in which a large capacitor is repetitively charged from a small capacitor. The resulting staircase wave is turned into a series of isolated pulses by switching to ground during the negative half-wave of the power supply. The leading edge of the seventh pulse is sloped to provide a start signal. In the control circuit a Zener diode is arranged to switch at one of the pulse levels. The control switch causes a positive or negative signal to be inserted in the gap following the operative pulse. The receiver station is also enabled by the same level in the same way and the control signal causes the required function to be performed. In another arrangement two receivers of this kind, each responding to a different amplitude pulse may be used to set flip-flops. The outputs of the flipflop gate power pulses to a lamp so that the lamp may be controlled to be off or to have one of three levels of brilliance. The state of operation of the lamp is indicated by its impedance. This impedance is converted to a signal which is relayed to an indicator at a predetermined instant in the cycle. The basic pulse train may be derived from the output of the car's alternator having therefore a variable frequency.