sunDial

while true do
  sleep(0)
  local time = os.time()
  if time >= 6 and time <= 18.5 then
    rs.setOutput("back", false)
    while time <= 18.5 do
    sleep(0)
      time = os.time()
    end
  else
    rs.setOutput("back", true)
    while time < 6 or time > 18.5 do
    sleep(0)
      time = os.time()
    end
  end
end