# Arduino UNO operated LED problem **URL:** \ **Category:** Arduino\ **Created:** [February 7, 2020, 5:25am UTC](https://community.sparkfun.com/t/arduino-uno-operated-led-problem/38839 "2020-02-07T05:25:12Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![dsavas](https://avatars.discourse-cdn.com/v4/letter/d/a9adbd/32.png) [@dsavas](https://community.sparkfun.com/u/dsavas)\ **Post date:** [February 7, 2020, 5:25am UTC](https://community.sparkfun.com/t/arduino-uno-operated-led-problem/38839/1 "2020-02-07T05:25:12Z")
Hi, I have a project where I am trying to light up two serially connected LEDs ([https://www.ledsupply.com/leds/custom-3 … -power-led](https://www.ledsupply.com/leds/custom-3-up-cree-high-power-led)) by using an Arduino UNO board and I purchased a relay control kit ([https://www.sparkfun.com/products/13815](https://www.sparkfun.com/products/13815)) to feed the system enough power. I established all the connections as depicted in this video: [https://learn.sparkfun.com/tutorials/be … 1580261792](https://learn.sparkfun.com/tutorials/beefcake-relay-control-hookup-guide?_ga=2.239267587.1641042775.1581052202-883739833.1580261792) I tried the system by using an arduino code that is supposed to keep the lights on at all times. Although the relay is on at all times (red light is on), the LEDs I am using are flashing with a certain frequency instead of staying on. I tried different codes for the arduino as well as different LEDs but the problem seems to be consistent with every combination I tried. Could you please instruct me how I can troubleshoot it. P.s.: I am using a 12V 2000mA power source. Thank you ---
**Author:** ![TS-Brandon](https://avatars.discourse-cdn.com/v4/letter/t/cc9497/32.png) [@TS-Brandon](https://community.sparkfun.com/u/TS-Brandon)\ **Post date:** [February 7, 2020, 4:38pm UTC](https://community.sparkfun.com/t/arduino-uno-operated-led-problem/38839/2 "2020-02-07T16:38:30Z")
Hello dsavas, While I can’t speak for the LED board or your power supply the issue could be in the code. If it is, we’re unable to support or debug custom code. That aside, I would check the LED board separately as well as the power supply. This would at least be a starting point.