can CTB16PC controller + a few relays = 2 separate shows?

merryoncherry

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Am only on the other side of country (via I-90), not world. Last one I mailed was well under $100.

I think the LoR modulates the 16 hot wires, and the neutral and ground are always connected. If you use a relay to intercept the neutral you only need 1 relay, rather than 15 to intercept all the other hot wires.

Some LoR can do 30A and have 2 power plugs. Those you would do 2 relays for neutral.

So hot1 -> comnect to both set 1 prop 1 and set 2 prop 1... and so on through 15
Netural->relay->set 1 prop 1-15 and opposite to set 2 prop 1-15
Ground to everything.
 

TerryK

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...
I also know that getting a second controller would solve this problem, but sometimes I like to do things the weird way. And since the displays would never be running at the same time anyway, it seems like a waste of channels to have half of them dormant. And since I have 2 channels that aren't being used I could technically have 3 different shows if none of them need more than 14 channels.

Looking forward to hear your thoughts.
Four, actually. If double throw relays are used.

To answer your question, I see no reason why it cannot be done. A bit atypical but nothing wrong with that. "Necessity is the mother of invention" as they say. A few thoughts however.

First, as mentioned while the neutrals could all be gathered and switched rather than the 'hots', that's not a good idea. Within the US, generally the hot side of a circuit is switched, not the neutral side. There are exceptions as would be expected but I don't think this is one of them. So, 14 relays could be wired into the hot side of the light strings with the coils all controlled by either output 15 or 16. Also as mentioned, it's quite acceptable (at least within the US) to switch the neutral along with the hot, or just the hot side, so either a SPDT or DPDT relay.

Best as I could determine from the manual, outputs are only an amp or 2 so a small form factor relay should be all right. Another item of note is, to help prevent triac damage, all light string outputs off, switch the 'show' relay, then activate the light string outputs. Doing this also means that the relays would see little to no load switching, thus small relay form factor again.

Last thought, 14 relays might be a bit much for an output. If your design tends in that direction, add a small relay (#15) to control the other 14. And even though the triacs should handle the 'turn-off' reasonable well, it would not hurt to add suppression across the relay coils; an MOV or RC Snubber. Relays should be 'Break Before Make' if double throw.
 

merryoncherry

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8 amps per, 15A total for a bank though.

 

everettdale

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Four, actually. If double throw relays are used.
I was thinking it would be four, but talked myself out of it somehow. lol.

Thanks for all the input on this. I think I'm going to give it a shot.
 

TerryK

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Yep. If you do at some point implement 3 or 4 show possibilities I would suggest a wiring diagram to help keep electrical paths through the relays straight.

I also did a bit more research on the triacs. According to the kit version the triac is a BTA16-600BW. The triac datasheet indicates 16 Amp (maximum amperage 'properly' heatsinked) at 600 Volt and is supposed to be electrically durable enough to not need a snubber. Unheatsinked, the triac is only rated at 1 Amp. The controller does have the triacs mounted to a common heatsink so; point being load equalization really should be looked at and kept in mind during the design phase. For example, if one knows that a particular output has a sizeable amperage requirement, physically avoid placing it next to another high amperage output. Try to keep some heatsink between them to give room for the generated heat to dissipate outwards.

Regarding noise suppression, keep in mind triacs turn off at the zero crossing so use of inductive/noise suppression for a SCR/triac load is debatable. Even though the triac does not need suppression according to the device datasheet, I would be inclined to implement something. As previously indicated, I'd probably use a MOV.

Relays: These maybe?
 

everettdale

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Try to keep some heatsink between them to give room for the generated heat to dissipate outwards.
I was thinking along these same lines, or possibly adding a fan to the case in some way. Which should have been there in the first place.

Thanks for the link, it's actually the one already in my shopping list, so it's nice to know I was on the right track.

Can you explain MOV please?
 

TerryK

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