Why only 4 channels?

[mark]

I've read about the different DIY controllers , been through the Wiki and all the threads here. What I'm curious about is why only four channels for each cat5 when there are eight wires in the cable? I realize one is supplying +5v, one is ground and four are controlling lights, but why not use the other two wires for a couple of extra channels?

[Wombat]

I think it has a bit to do with Binary. 6 doesnt go into 16

The chips used have 8 or 16 bits so there would end up being either unused outputs or SSR's with unused outputs if there was more than 4

Hope that explains it
Wombat

[RJ]

That and most electrical boxes are setup for two receptical with 2 plugs each. So I think it was a natural match.

RJ

[Jeff Millard]

I've been considering making some 7 channel SSRs that source input to the opto, using the 8th wire for ground. Is there interest in this here? I have plans for about 300 to 500 channels for arches and dividing that into 4 isn't feasable at all. This is only useful for people using DIO as all the controllers here are designed around the 4 SSR with sinked outputs.
Jeff

[Ronp]

I run 6 ch outlet strips i use 7 wires 8)

[Matt]

Keep in mind, you don't necessarily have to use CAT5 cable. I use 6 conductor phone cable.

-Matt

[xmus]

i think you get 4 channels from one cat 5 run to a SSR because

4 -> for the signal to each opto isolator for 4 channels
1 -> 5VDC
1 -> Ground
1 -> optional I think some people run ZC down the cat 5.

that leaves 1 spare.

But I've never actually built one..... but you could check out the schematic in wiki.

[JetMech]

What I'm curious about is why only four channels for each cat5 when there are eight wires in the cable?

Because ....
Sean Bowf built it and it was good.
Then he HowTo'ed it and it was good.
http://computerchristmas.com/christmas/link-how_to/HowToId-68/4-channel_SSR_to_go_with_the_controller_in_the_How_T o
The people saw that it was good and they followed.
The people coop'ed it and saw that it was good.

Sorta became the de facto standard, the only reason I know of for cat5 is price and availabilty.
(Some people don't actually pay for it, you know who you are :wink: )

John

[daviddth]

my home made SSR setup in 6 way powerboards uses 6 signal & 1 (actually 2) grounds. I'd much prefer to go for 6 or 7 SSR's per cable as mine are all closely located, but I'll stick to the 4 setup for the next 128 chans & thats it