Dimming Grinches for Dummies

**piesrule58** · 12-27-2008, 08:36 PM

I have a request that I hope someone can help me with. I have had a very successful show this year running 3 Grinches with no dimming. Next year I want to add 2 more Grinches and I want to make all 5 of them dim. What I need is an easy to understand description (drawings or pictures would be good) of a 5 Grinch setup with whatever else I need to make it dim. I am in OZ so power supply here is 240v. Thankyou in advance.

Cheers, Terry

**Trip** · 12-27-2008, 08:43 PM

You need a ren-c for each one to do it.

http://www.doityourselfchristmas.com...hp?title=Ren-C

**TERBObob** · 12-27-2008, 10:34 PM

To do multiplies ...

http://www.doityourselfchristmas.com...C_Layout_2.jpg

**P. Short** · 12-27-2008, 11:32 PM

I'm not sure that I would recommend dimming a Grinch if you can help it, too many people have been having difficulties. Rather than buying two more Grinches I recommend that you find some solution that was designed to be dimmed from the very beginning, rather than as an after-thought.

Just my opinion...

**sjwilson122** · 12-27-2008, 11:49 PM

If I understand the channel count restrictions with the 57600 baud rate correctly you would have to run the two additional grinches on a second serial port also.

**toodle_pipsky** · 12-28-2008, 07:37 AM

Ok, as promised here's a pic. Ignore the mess of cables and wires

, that's what I get for starting all organised then rushing at the last minute. Anyway . . . .

Going along the lines of what Mr Short has said, maybe a thought would be to go for another type of Renard board instead of 2 more Grinches. I'd say still go for Ren-C's to dim what you have rather than just ditch your hard work and money spent this year. Even ditching the Ginches for something like Ren 64 is probably not a great idea since Allegro ICs are hard to get and MBIs are expensive. If you're wanting to go with 2 more Grinches because that's what you're comfortable with, that's perfectly valid too and I say go with it. Who's to say you won't have a multitude of problems trying to get different boards going. You have the luxury of time, it's all just food for thought.

There is nothing scary really about adding a Ren-C to dim. You're starting with a tried and working system (i.e. your Grinches and SSRs) so that will make any kind of troubleshooting fairly easy. The boards of course available from the lovely wjohn, and happy news the parts you can get from a local Jaycar store (I'll have a dig around for the BOM) for around about $15. The trickiest part is the ZC signal (zero crossing) - the simplest way I can explain it is that it's just an electrical signal that the Ren-C uses to know how to dim (I think that's right - correct me if I'm wrong). And the most confusing part is that there is a few ways to do it. I'll explain how I did it, and someone else can chime in with any of the other ways.

Because you said you're only using incandescents, you only need to make 1 teeny little connector cable between Grinch and Ren-C. Power comes from the Grinch with a little jumper placed in the 2 pins near the power in. And all you need to do is ditch the parallel port adaptor and get a serial adaptor.

I think that summarises the Ren-C, well in terms of the physical set up. Hopefully that makes the Wiki a little less intimidating too. See what you think.

**daviddth** · 12-28-2008, 02:19 PM

Hell, I run 4 dimmed grinches here with no real issues. There are a few things to remember tho - dont dim below 20% unless you want flickers, 57200 baud allows 128 chans easily (You should, and I did manage) be able to run 256 or a bit more on 1 serial port with the new plugins and 50msec timing, but it was not worth the worry

I love my ren-c's, but all future stuff will be ren 16 or 64's as the dimming is a little smoother and also goes down to 10% with no issues.

**piesrule58** · 12-28-2008, 07:01 PM

Originally Posted by toodle_pipsky

The trickiest part is the ZC signal (zero crossing) - the simplest way I can explain it is that it's just an electrical signal that the Ren-C uses to know how to dim (I think that's right - correct me if I'm wrong). And the most confusing part is that there is a few ways to do it. I'll explain how I did it, and someone else can chime in with any of the other ways.

.

Thanks guys

I think I will be ok and I know where to come if I run into trouble. I already have the 2 extra Grinches otherwise I may have gone with the Renards.
Toodles, you mentioned there is a few ways to get the ZC signal and I think you forgot to add how you did yours. I know I will need 5 Ren C boards, but how many ZC boards will I need? Also, do I need to make a Serial adapter or can I buy one at Dick Smith, Jaycar etc?
Thanks again for all the help.

Cheers, Terry

**jpb** · 12-28-2008, 09:45 PM

Terry,
Sinnie from Singleton has been sorting out his ZC in this thread http://doityourselfchristmas.com/for...ead.php?t=5658

I am planning to go from 1 grinch to 2 this year and dim one with RenC (maybe both).
I thought about the REN64 but it looks too expensive for me.

Jon

**toodle_pipsky** · 12-28-2008, 10:29 PM

Sorry, Terry, I didn't forget I thought "I'll do it later when I can get a better picture of the ZC" - I just assumed my thoughts beamed across the internet to you . . . . ;)

The link jpd has given is the ZC I used. It's what another member, scorpia, suggested to me and from what I understand it's how the other Renard boards generate their ZC. It uses a wall transformer from any of your sets of lights (you must have a gazillion of them), I just used one from an LED set because it was nice and small. Here's a quick drawing of what it looks like.