Description:Timing from Microseconds to HOURSSimple CircuitryPrecision Pulse Generation / Timing,FMAX = 500 KHzUse a single 4 to 16 VDC supplyExcellent temperature stability 0.005% / °CAdjustable Duty CycleCountless Application and Information SourcesChip (NE555) Characteristic:When unconnected with the supply power, the state of the module is "NO" [ normal open ], CB and COM are conductive. CK and COM are unconductive.When connected with the supply power, delay for 0-10s, the module will in the state of "NC" [ normal closed ], CB and COM are unconductive, CK and COM is conductiveSpecification:Module Properties : NE555 chipDimension : 77 (L) x 23 (W) x 18 (H) mm (with potentiometer)Input voltage : DC12VAdjustable time : 0 to 10secControl voltage : AC 0~250V / max. 10A, DC 0~30V / max. 10AMax. loading : 2200WConnection drawing:We suggest you using a diode connectiong to the VCC in series. In order to prevent from damaging chip of Power Reverse or Voltage Fluctuation. ( The board does not add diode because the power would not enough to pull-in the relay for the buck from diode when power is too low. )Package included:5 x Delay Timer Switch