volts in the day when the photo switch p1 is off the photo voltaic array 105 charges the capacitor array c2 at night the photo switch p1 closes and supplies electrical power from the capacitor array c2 to the timer chip 101 to operate the light emitting diodes 35 39 51 amp 73 under rainy conditions which occur during the day and once the ambient light is low enough the timer chip 101 will go into operation it is expected that the photo switch p1 will have a sufficiently high threshold that the timer chip 101 will probably not operate during periods where any significant light falls on the photo voltaic array 105 ideally the photo switch p1 should come on only under the darkest conditions likely to be encountered in order to conserve charge and thus to conserve the energy capacity of the capacitors it is preferred to set the oscillation frequency of the timer chip 101 to have a duty cycle of from about 6 to about 15 with triggering to occur more often than one second a low duty cycle can be used where the time during which the light emitting diodes 35 39 51 amp 73 will be on for 0 050 seconds and off for a duration of 0 779 seconds before being turned on again this corresponds to a duty of 6 03 a high duty cycle might energize the light emitting diodes 35 39 51 amp 73 for 0 124 seconds followed by an off time of 0 705 for a 15 duty cycle a medium duty cycle would be an on time of 0 107 seconds followed by.