It's an "optocoupler" relay module operating at 12 Volt. Does this mean that 12 V is galvanic isolated from the arduino, that should control the relays? My first impression was: I am missing a separate ground for the relay control and for the arduino! However, after some study I discovered that you CAN operate the board with galvanic isolated 12 V and the arduino's 5 V. How? Don't use the straps!! So don't connect the 4 middle pins with straps to Ground or to VCC of the relay module, but connect these 4 pins to the arduino's ground! Now the 12V and the arduino's 5V are galvanic isolated! See photo!

It's an "optocoupler" relay module operating at 12 Volt. Does this mean that 12 V is galvanic isolated from the arduino, that should control the relays? My first impression was: I am missing a separate ground for the relay control and for the arduino! However, after some study I discovered that you CAN operate the board with galvanic isolated 12 V and the arduino's 5 V. How? Don't use the straps!! So don't connect the 4 middle pins with straps to Ground or to VCC of the relay module, but connect these 4 pins to the arduino's ground! Now the 12V and the arduino's 5V are galvanic isolated! See photo!

It's an "optocoupler" relay module operating at 12 Volt. Does this mean that 12 V is galvanic isolated from the arduino, that should control the relays? My first impression was: I am missing a separate ground for the relay control and for the arduino! However, after some study I discovered that you CAN operate the board with galvanic isolated 12 V and the arduino's 5 V. How? Don't use the straps!! So don't connect the 4 middle pins with straps to Ground or to VCC of the relay module, but connect these 4 pins to the arduino's ground! Now the 12V and the arduino's 5V are galvanic isolated! See photo!

Item as described and expected. Fast delivery and service from Banggood :)

Item as described and expected. Fast delivery and service from Banggood :)

Item as described and expected. Fast delivery and service from Banggood :)