• Timing from Microseconds to HOURS
• Simple Circuitry
• Precision Pulse Generation / Timing,
• FMAX = 500 KHz
• Use a single 4 to 16 VDC supply
• Excellent temperature stability 0.005% / °C
• Adjustable Duty Cycle
• Countless Application and Information Sources

Chip (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 conductive

• Module Properties : NE555 chip
• Dimension : 77 (L) x 23 (W) x 18 (H) mm (with potentiometer)
• Input voltage : DC12V
• Adjustable time : 0 to 10sec
• Control voltage : AC 0~250V / max. 10A, DC 0~30V / max. 10A
• Max. loading : 2200W

We suggest  using a diode connected to the VCC in series, in order to prevent damaging the chip due to overvoltage or reverse polarity. (The board does not have a  diode because relay would not activate if power used is very low)