Light Chaser Assistance

Hi All,

I always wanted to have a fancy light display at my home during Xmas. I could spend lots of money on LOR (Light-O-Rama), or I could build something myself. So my project has been to use my Arduino and build my own light chaser hardware/software. I'm essentially all done, but I need help advancing my project.

Let's start with what I have done and the basics on how it works. Currently using an Arduino Duemilanove, but soon upgrading to a Mega. Each digital pin is connected to a circuit to drive a relay. Each relay will power 1 set of lights. I'm just using Xmas lights, some run on 240V others use a 12V transformer. I then have an app on my PC that I have written which sends the sequence commands to the arduino. The arduino processes these and essentially just switches the pins high or low, hence turning the lights on or off. So on my Duemilanove I basically have 14 channels - on the Mega, 54 channels.

Took me a month or 2 to get to this stage working on ti in my spare time - but now it all runs really nicely. The software can drive mulitple arduino's, theoritcally as many as you have USB ports on the PC. The only concern is power consumption and making sure you don't blow a fuse in your house with all the lights connected.

But anyway, the next step is rather than just having lights on or off, but to fade them in and out. I presume I would do this using PWM, but I do not know how to use the PWM on the arduino to control an external power supply (12V or 240V).

Can anyone help out with this? Let me know if you need more info.

Thanks.

It would be difficult to "fade" lights controlled by relays on the AC-side of their power circuit. Relays just aren't fast enough. A typical AC dimmer circuit will shut off the power part way through each half-cycle of AC power, 120 (probably 100 in your case) times each second, using a fast semiconductor switch like a triac....

bump

Someone suggested using a solid state relay. I'm already using an SSR to switch the lights on and off. So I hooked up one of the channels to a PWM pin and tried it - the lights fade in and out ok, except with a lot of visible flicker. I tried changing the frequency of the PWM pin but this didn't make much of a difference...

Still looking for help.... Thanks.

It has to be the right type of SSR not just any old one. One that offers phase angle control.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1230333861/0

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1252713674/1