Here is a rough block diagram for a method that uses 4000 series logic ICs.
The CD4060 is configured to give an output on Q14 of one cycle every 300 seconds. The capacitor, resistor and diode differentiate the output of the CD4060 to produce a short positive pulse on the rising edge of the waveform. This pulse does two things. 1 It resets the output latch which switches off the light. (If it was in the on state.) It also triggers the CD4047 which is configured in monostable mode to give a 1 second output pulse. The data input of the CD4013 is connected to the output of the comparator that converts the output of the LDR to a high level when it is dark. The not Q output (Which will go high at the end of the 1 second monostable period.) is differentiated to clock in the state of the comparator into the output latch. (So if the comparator was giving an output for dark it turns on the light. If it is giving a low output for light the output latch remains in the reset state and the light remains off.) You will need to look at the data sheet for the CD4047 to see how to configure it for monostble operation.
Les.
The CD4060 is configured to give an output on Q14 of one cycle every 300 seconds. The capacitor, resistor and diode differentiate the output of the CD4060 to produce a short positive pulse on the rising edge of the waveform. This pulse does two things. 1 It resets the output latch which switches off the light. (If it was in the on state.) It also triggers the CD4047 which is configured in monostable mode to give a 1 second output pulse. The data input of the CD4013 is connected to the output of the comparator that converts the output of the LDR to a high level when it is dark. The not Q output (Which will go high at the end of the 1 second monostable period.) is differentiated to clock in the state of the comparator into the output latch. (So if the comparator was giving an output for dark it turns on the light. If it is giving a low output for light the output latch remains in the reset state and the light remains off.) You will need to look at the data sheet for the CD4047 to see how to configure it for monostble operation.
Les.
