Adjustable Infinite Cycle Timer Delay On/Off Switch Relay Module (DC5V,0-15min) Features: It is a timer relay module with high precision, stable and reliable performance. Support 2 modes, mon mode(once) and cycle mode, and you can simply switch mode by adjusting the jumper. There are many voltage and time range for your choice, both "on" time and "off" time are adjustable. It is great to control the reciprocating stroke, or repetitive power on and off for equipment and products burn-in test. Widely used on timer operating equipment, machine repetitive test circuit, fish tank intermittent pump, etc. Specifications: Max. Load Capacity: 10A250VAC, 10A30VDC Size: 70*20mm / 2.75*0.78" Time Error: <2% T1(the relay turn on delay time),T2(the relay turn off delay time)  Once Mode(Jumper OP3): 1. The module Power-on, When triggered the relay is switched on, delay T1, and the relay disconnected. 2. When triggered on the delay process, again triggered, it will immediately interrupt the delay. Cycle Mode(Jumper OP4): 1. The module Power-on, When triggered the relay is switched on, delay T1,and the relay is disconnected, delay T2, the relay is switched on again. Such cycle. T1 and T2 are set by two adjustable resistors, respectively. 2. When triggered on the delay process, again triggered, it will immediately interrupt the delay. How to Set Time Quickly: Time can be quickly set by measuring voltage(Uc) of resistor. Take a 5V 15min module as example. If Uc=2V, time=2V/5V*15min=6min. Package Includes: 1 x Timer Relay Module