This is a unique channel relay that works with 5v and a positive signal.

2 x 1k SMD 805 resistors;

1 x SMD Diode that suport more than 5v of reverse voltage;

1 x 5v relay;

1 NPN sot23 transistor similar of BC548/337;

1 Optocoupler TLP621 or PC817;

1 double face PCB with 50mm x 23mm