LED staying on after first relay trigger I seem to have a strange issue with a simple circuit involving a relay. 

The problem is that the relay appears to work absolutely fine (judging from the onboard led) but the the led stays on after the first pull up on the relay. 

It doesn't turn off and match the onboard relay led. I'm sure it's something minor but I can't seem to spot the problem.

I've attached a video and the code below. Thanks in advance

video

#include &lt;Arduino.h&gt;
int Relay = 3;

void setup()
{
  pinMode(Relay, OUTPUT);     //Set Pin3 as output
}
void loop()
{
          digitalWrite(Relay, HIGH);   //Turn off relay
          delay(2000);
          digitalWrite(Relay, LOW);    //Turn on relay
          delay(2000);
}
If using a solid state relay, consider such a device may rely on driving a load using AC rather than DC.  That is, the solid state relay my not turn off until a zero crossing occurs.  Solid state relays intended to switch DC driven loads are normally designed using MOSFET switches.  Solid state relays intended to switch AC driven loads are normally designed using SRC or TRIAC switches.  Read more about this here.