The main function of the circuit is to delay it can pull, delay the release of three working modes delay conversion. The so-called pull-delay means that the relay in the boot preferences, the relay does not pull. Only when the timer reaches the preset time, the relay was energized. Delay and delay the release of the pull the contrary, in turn relay after the preset, when the timer reaches the preset time, the relay releases. Delay and delay the release of Pick two working conditions for the one-time operation, when the relay to complete a work process, the control section of the circuit into a stable state. Delay the work cycle is as long as the boot state, the circuit will be in accordance with good pre-opening and stop time interval automatic cycle, and never stop until the power switch on or switch off the work of the state so far. The circuit as shown.