# Relay 30A 5v **URL:** \ **Category:** General Electronics\ **Created:** [June 2, 2020, 7:57pm UTC](https://forum.arduino.cc/t/relay-30a-5v/658457 "2020-06-02T19:57:44Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![gui21540](https://avatars.discourse-cdn.com/v4/letter/g/da6949/32.png) [@gui21540](https://forum.arduino.cc/u/gui21540)\ **Post date:** [June 2, 2020, 7:57pm UTC](https://forum.arduino.cc/t/relay-30a-5v/658457/1 "2020-06-02T19:57:44Z")
hello, I just bought this relay. Could you tell me how to connect it. ![](https://europe1.discourse-cdn.com/arduino/original/4X/d/2/2/d221d115c40459cc7f8ee3665bdc8d41c8f94a19.jpeg) ---
**Author:** ![idv7](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/idv7/32/522153_2.png) [@idv7](https://forum.arduino.cc/u/idv7)\ **Post date:** [June 2, 2020, 8:18pm UTC](https://forum.arduino.cc/t/relay-30a-5v/658457/2 "2020-06-02T20:18:09Z")
very easy, connect vcc to 5v, gnd to gnd and the other two pins to 2digital pins on the arduino, set it to HIGH if you want the relay to switch ... ---
**Author:** ![gui21540](https://avatars.discourse-cdn.com/v4/letter/g/da6949/32.png) [@gui21540](https://forum.arduino.cc/u/gui21540)\ **Post date:** [June 2, 2020, 8:25pm UTC](https://forum.arduino.cc/t/relay-30a-5v/658457/3 "2020-06-02T20:25:25Z")
that's what I did. the relay LED lights up. but the relay does not trigger ---
**Author:** ![raschemmel](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/raschemmel/32/241282_2.png) [@raschemmel](https://forum.arduino.cc/u/raschemmel)\ **Post date:** [June 2, 2020, 10:16pm UTC](https://forum.arduino.cc/t/relay-30a-5v/658457/4 "2020-06-02T22:16:18Z")
Is COM connected to GND ? ---
**Author:** ![sone0121](https://avatars.discourse-cdn.com/v4/letter/s/6a8cbe/32.png) [@sone0121](https://forum.arduino.cc/u/sone0121)\ **Post date:** [June 3, 2020, 1:57am UTC](https://forum.arduino.cc/t/relay-30a-5v/658457/5 "2020-06-03T01:57:46Z")
there are some PINs sticking on the side, they may need jumpers, can you show picture from other side, it might help you to get ppl to help you 🙂 and dont jump anything without knowing what it does, just to make that clear, as you may end up frying your module ! ---
**Author:** ![Paul\_B](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paul_b/32/216376_2.png) [@Paul\_B](https://forum.arduino.cc/u/Paul_B)\ **Post date:** [June 3, 2020, 11:02pm UTC](https://forum.arduino.cc/t/relay-30a-5v/658457/6 "2020-06-03T23:02:27Z")
> sone0121: > there are some PINs sticking on the side, they may need jumpers, can you show picture from other side, it might help you to get ppl to help you Correct. 😀 You have to jumper COM to HIGH (for **both** relays) if you want to connect the COM terminal to ground and trigger with HIGH level, or vice versa. Or possibly the other way round, I haven't the time just now to research it. Point is, you **must** set both jumpers to either "High" or "Low". No harm in playing around with it to determine which. Note this design uses AC opto-isolators to make this choice possible. The "COM" terminal should connect to either Vcc or ground on the controlling Arduino **together** with the wires to the outputs for the "IN" terminals, the "DC+" and "DC-" terminals should connect as a separate paired cable back to the relay power supply to maintain isolation. * * * On further thought, I really cannot figure out what those jumpers are supposed to do. I am unable to find a schematic of this particular sort of relay module - I would have to see it myself and trace out the circuit. 🙄 ---
**Author:** ![dlloyd](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/dlloyd/32/751911_2.png) [@dlloyd](https://forum.arduino.cc/u/dlloyd)\ **Post date:** [June 4, 2020, 6:02pm UTC](https://forum.arduino.cc/t/relay-30a-5v/658457/7 "2020-06-04T18:02:09Z")
I found a bottom view pic of the 12V version ... COM is connected to GND. ![](https://europe1.discourse-cdn.com/arduino/original/4X/c/c/2/cc29a753edf834e978dfd05c436891c90f8e6fe9.jpeg) The circuit might be a dual version of this. To get full opto isolation no jumpers are required. Arduino Connections: Trigger1, Trigger2, CH1, CH2. ![](https://europe1.discourse-cdn.com/arduino/original/4X/a/3/d/a3d867971799cb4c9ed4032a5085fb3dc45f9876.png) ![RM_schematic.png](https://europe1.discourse-cdn.com/arduino/original/4X/a/3/d/a3d867971799cb4c9ed4032a5085fb3dc45f9876.png) ---
**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\ **Post date:** [May 6, 2021, 2:33am UTC](https://forum.arduino.cc/t/relay-30a-5v/658457/8 "2021-05-06T02:33:27Z")