Hooking up Christmas lights to Arduino

I decided to try syncing some LEDs to music using an arduino and was able to make it work with no problems. I am now trying to go a bit further and sync christmas lights to music. I came across this instructables: http://www.instructables.com/id/Arduino-Christmas-Light-Controller/?ALLSTEPS. Although the code for the blinking is my own I am using the circuit he has to power the lights. When I hook up the circuit to the arduino, the relay clicks whenever the lights should be blinking but the lights don't go on at all. Does anyone have any suggestions on how to fix this?

Clicking relays? I'd recommend against mechanical relays for this sort of thing. Way too much lag. Use some solid state relays. It's quite possible that between the lag of the relays, and the time it takes your bulbs to light up, you're turning them back off before they can incandesce. Check out my setup: http://www.neonsquirt.com/arduinoxmas/ Solid state relays are actually far simpler to wire to an Arduino than mechanical ones.

If the relay is clicking, it's probably working. I don't suppose you have a multimeter?

The AC side of the relay is probably wired incorrectly. In fact, the schematic on the instructables website doesn't show any AC power applied... It just shows a the relay contacts connected to an AC socket with no power. The current needs to flow through the relay contacts just like regular-old light switch.

If everything is wired correctly, and you disconect the 2 wires going to the relay, and then connect those two wires together, the light should go on. (Turn the power off before messing with the AC wiring. ;) )

i used a moc + triac. looks awesome. by me: http://dduino.blogspot.com/2012/03/moc-triac-ardunio.html

Be carefuly with triacs. If you are driving Incandescent lamps this is fine, but if you are driving ANYTHING else this could cause various malfunctions that may likely result in a FIRE. The easiest way to test the relays may be to upload the blink example and connect your relay drivers one by one to pin 13 and see if the load turns on and off based on L flashing. If this works then you have a problem with your Arduino turning the relays on and off too quickly and the armature isn't making contact or making and breaking so quickly that your lamps have not reached temperature as mentioned above.

what do you mean? i used the moc/triac as in my post there with the resistive load schematic + LED Christmas lights. no issues.

Sorry I haven’t responded in awhile. I’ve been busy with school work and other projects. I tried hooking up the relay I have using this schematic http://www.plcs.net/relay5.gif. The relay was clicking but again the lights didn’t go on so I’m thinking it’s the lights not being able to turn on and off quick enough. I’ve never really used relays before so would using a solid state relay as suggested fix this problem? Also would using the mechanical relay I already have with LED Christmas lights work as well? Any help would be greatly appreciated.


you should be able to at least see something. tried a different bulb? use a DMM to check for voltage on the relay? switch at a lower rate for testing?

I ended up switching out all of the wires for new ones and it started working. Must have been a bad wire in there somewhere. Of course its something stupid like that. Thanks everyone for all the information and help though.