4 relay extension board for Micro:bit - plug and play
Here is a super easy module to use. Plug the board on Micro:bit's edge connector and the relay can be controled via the P13, P14, P15, P16 pins.
Each relay do have normaly open & normaly closed contacts (namely NO & NC). The normaly open (NO) is active when the relay is activated.
Each relay can drive a current of 3A @ 24V DC.
The relays have 5V coils so the Micro:bit must be connected to USB to have the required 5V.