relay control will this work?

**homegrowncorals** · 03-09-2012, 09:48 AM

OK I'm a brain dead newbie. i am using some tennsylights 16 light boards for my Christmas lights and was wanting to turn off and on some 110 volt motorized items(rotisserie motor / inflatables transformer) once or twice a night.
can one drive a relay right from the control card via a light channel or might there be a better simpler way.

**raplass** · 03-09-2012, 10:23 AM

Welcome! Yes, if its a control board channel normally provides 120 V AC and the relay has a 120 V AC coil. I use the NC side of relays to keep some lights on when a sequence isn't running. Just don't forget the channel's purpose and start to dim it. Also keep in mind that is recommended for Vixen to turn off all channels at the end of a given sequence. If you simply want a display element on during prime time, a timer will likely be the simpler approach.

**homegrowncorals** · 03-09-2012, 11:04 AM

thank you for the fast responds, yes a timer for the inflatables was a thought i had, but other elements i was wanting to run with just certain sequences. and its good to know the relay idea will work for them.

**homegrowncorals** · 03-09-2012, 02:11 PM

Just to be sure i understand this right.
the relay coil is energized with the leads (110 v) the Christmas lights would plug into, and the rotisserie and the power for it will be separate switched with the contact side of the relay. and the relay wont fry the triac as long as i don't dim that channel?
this is the board im working with.

**KeithW** · 03-10-2012, 12:06 PM

I do the same with a fog machine - elsewhere someone was worried about a relay coil affecting the triac - I haven't noticed this, but if there are worries about backfeeding when turning off the channel, some have suggested a diode. I haven't done this, but when I do my rotisserie motor, maybe I'll just stick an el-cheapo diode inline with my ice cube relays - only problem I have is the audible -click- during on/off - but if you're running during an entire sequence, I see no issues.

**ErnieHorning** · 03-11-2012, 12:15 AM

Originally Posted by homegrowncorals

... and the relay wont fry the triac as long as i don't dim that channel?

You're not going to fry the TRIAC by dimming; TRIAC's don't work that way. The dimming just won't work the way that you would expected because of a phase shift between voltage and current. Because of the phase shift, you may need to add a resistive load across the coil to make it turn on/off correctly. An acceptable load would be a C7 size light bulb. I recommend using two, in case one burns out.

**raplass** · 03-11-2012, 12:11 PM

Originally Posted by KeithW

- elsewhere someone was worried about a relay coil affecting the triac - I haven't noticed this, but if there are worries about backfeeding when turning off the channel, some have suggested a diode. I haven't done this, but when I do my rotisserie motor, maybe I'll just stick an el-cheapo diode inline with my ice cube relays - only problem I have is the audible -click- during on/off - but if you're running during an entire sequence, I see no issues.

Keith, are you referring to what Don did with his Megatree?

http://downloads.eshepherdsoflight.c...d-MidiTree.pdf

Can't find the associated forum thread at the moment, but his instructions are quite clear. I believe in that case, his use of diodes was to reduce the channel count used by the tree via multiplexing, but the drawback comes when you want to turn on all colors on at once. He elected not to do this for current load reasons. The C7s across the relay coils are to ensure there is enough current draw to latch the triacs on since you don't want the relays to switch states until Vixen sends more change commands to the triacs. I have not had a problem leaving the C7s off.

I have been using these relays: LY1-0-AC1 - Omron General Purpose / Industrial Relays - PCB SPDT 110-120VAC, with corresponding sockets for easy replacement. Considering adding "MY series" units this year for lines with low current loads. Both have coils drawing ~9 milliamps. And yes, there is a significant on/off click. As usual, buy a couple units first and experiment before buying needed quantities of something that didn't work as expected. Rich

P.S., Thanks Ernie, forgot to mention the potential phase difference issue, coils being inductive loads...

**KeithW** · 03-12-2012, 02:06 AM

Rich,
I'm an idiot, I think I was remembering someone was using a dc relay - not even applicable for this. That's a better spec/price than my radio shack relay - I was just impatient to start hacking my fog machine. Now you've got me curious about Don's megatree!

**homegrowncorals** · 03-15-2012, 09:56 AM

OK one last dumb question before i run out and pick up parts to test this out,

when adding the c7 bulb do i connect it in series on one of the legs of the coil, or in parallel across.

sorry for so many newbie questions just don't want to see and funny blue smoke.

**ErnieHorning** · 03-15-2012, 10:24 AM

Originally Posted by homegrowncorals

when adding the c7 bulb do i connect it in series on one of the legs of the coil, or in parallel across.

I would just try it to see if it’s necessary, it depends on the relay and the TRIAC. If needed, the C7 goes in parallel.

BTW, I would recommend that you use two C7’s in parallel. There’s a pretty good chance that one bulb will burnout but significantly less that you would burnout two.