View Full Version : Dimming the grinch - confused

02-23-2010, 12:30 PM
Hi, I have so far built my grinch this year and have 64 channels working woo :) Im very surprised at my self, I still however have to make my SSR's, but before I started I was thinking about dimming some channels, I wouldn't be dimming all of them just my RBG LED spot lights so I can color mix. Can some one please tell me what I need to do? I'm a bit confused about what parts I need and then how it all comes together? I'm in the UK as well which means all my values are different from the ones here which makes things just that little bit harder.

Can someone please help me?

Thanks Steve

02-23-2010, 12:41 PM
Hi, Steve.

A Grinch in its native state doesn't dim anything -- it's an on/off controller. It can be made dimmable with either the Ren-C converter (if you plan to use the Renard protocol) or a DMX adapter for the Grinch if you choose to use DMX. Either will work but it makes ALL the channels dimmable, not just some. Because the Grinch requires external SSRs, the type of ssr you make should be a kind that is appropriate for the lights you choose to control. Since the Grinch outputs in groups of 4 channels, you'd need 16 four-channel SSRs to max out the 64 channels that are in a Grinch. You could use a combination of AC ssrs for controlling mini-lights and DC ssrs for controlling LEDs.

There's lots of help for folks who use 220v current -- I'm sure they'll chime in here!

02-23-2010, 12:57 PM
Do I need a Ren-T? or is that for something else? and what kind of SSR should I use? I have 4 triacs just to make a trial SSRmboard, but I believe there just on or off?

Thanks Steve

02-23-2010, 06:32 PM
Does anyone have the ren-c in a express pcb file? so i could etch it myself?

thank steve

02-23-2010, 07:10 PM
You can get Ren-C board from wjohn. They're cheap, and it's a pretty complicated board that would be very difficult to etch on your own. For one thing, it's two-sided.

02-23-2010, 07:17 PM
Ok thanks I will PM him, what else do I need then, I have my grinch and if I make a ren-c board, what else do I need and how do I make the SSR? Sorry about all the questions im new to this and a little confused

02-23-2010, 07:27 PM
You'll want to soak up everything you can in the Grinch forum as it relates to Ren-C, and info in the WIKI as well. You'll need a way to provide a "zero cross signal" or ZC signal to the Ren-C. Without going into a long diatribe of why this is necessary, suffice to say that it is or dimming won't work. There is a ZC board design in the copper section of the file library for you to home-etch if you like. You don't need a copper circuitboard though -- you can also get by with just a perfboard, some wire and a soldering iron.

You will need to make a cable that goes from a serial port into a RJ45 connector jack. Info in the Wiki on making the cable is readily available. This cable will connect the computer to the Ren-C.

You will need two other short cables (8-12 inches long or so) with RJ45 connections on each end. These cables will connect the Grinch to the Ren-C.

Since you already have the grinch working, you already know how to get 5v power to it. That won't change.

The ZC board you make will connect to the Ren-C by two small wires. It's not much voltage at all, but it's critically important to Ren-C operation.

There, you have a short treatise of nuts-and-bolts to getting it working. Now you need to spend time in the Grinch forum and the Wiki.

02-23-2010, 08:21 PM
Everything Dirk has written is good info. keep asking as many questions as you like, ( the only dumb question is the one..... never mind)
I would encourage you to consider the Grinch Dimmer by RPM. They work a treat. I made one using a ready made PCB and one on Verobaord.
Being DMX, can can add other ready made DMX fixtures to your display like Smoke, Strobes etc if they too are DMX controlled.
the circuit and firmware can be found here (http://www.doityourselfchristmas.com/forums/dynamics/showentry.php?e=29&catid=26)

02-24-2010, 12:19 PM
OK thanks I will look into both options, once ive decided which one I'm using what do I do about switches I'm assuming my triac wont be suitable as its on/off only, can you point in the direction of a ssr that can dim for both ac and dc?

Thanks Steve

02-24-2010, 12:31 PM
Should you end up using Zero cross H1aa circuit from here the resistor values will be different for 240v. I you,s a an old 12v ct transformer and two diodes method. It works. Best thing to do is Read, read, read, and read some more. The clever guys are all good guys here and will not leave you out to dry.

02-24-2010, 04:54 PM
can you point in the direction of a ssr that can dim for both ac and dc?
Sorry they don't exist. Some ppl use the AC SSRs to dim LEDs by adding Bridge rectifiers between the SSR and the LED string.
But if you are just starting out I would suggest you use AC SSRs for your incandescent lights and DC SSRs for your LEDs.
One point to realise is although you state you don't want to Dim your AC lights, you will have the choice to in the future. I use a combination of Rope lights and LEDs and find the rope lights set to 50-60% gives a good mix with the LEDs. You will discover this sort of thing latter.
The cost of a non-dimming AC SSR is only marginally lower than a dimming AC SSR. it keeps your options open.

The Wiki details most of the readily available SSRs.
the SSROZ (http://www.doityourselfchristmas.com/wiki/index.php?title=Solid_State_Relays) is the most common.
the SSREZ (http://doityourselfchristmas.com/wiki/index.php?title=SSRez) is an updated version and has some good "creature comfort" additions.
the DCSSR (http://doityourselfchristmas.com/wiki/index.php?title=4_Channel_DCSSR_Assembly_Instructi ons) is ideal for you LEDs

Ready made PCB are available for the above three SSRs.

02-24-2010, 05:16 PM
Are the 3 types of SSR's suggested capable of dimming?

Thanks for all your advice everyone

02-24-2010, 05:51 PM
for the AC Dimmers the only device that prevents dimming is the Opto-coupler. if built as per the wiki, they will dimable.

The SSR are simple relays, the dimming is performed by your controller. But the import point here is the SSR mentioned are dimable. if you were to use the Grinch connected directly to your printer port, it would all be ON OFF and no dimming. Adding the REN C or the Grinch Dimmer, gives you the dimming capability.

02-24-2010, 05:59 PM
So if I build the the SSROZ as described in the wiki and the DCSSR as described I will be able to dim my lights? as long as I have a ren-c attached to my Grinch? I just want to verify everything before I order loads of parts

thanks steve

02-24-2010, 06:57 PM

02-27-2010, 08:43 AM
OK, that's great :), Ive went to mouser and made a list of the items I will need but I have come across some problems, some of the items are on back order and wont be ready until the 16/8/2010 which is cutting it a bit close to have everything ready and some items are now obsolete, I was wondering if anyone had substitutes or something. The items that are are going to cause me issues are the 512-2N3904TA, 859-MOC3023, 511-STF20NF06 also items 571-1032394 & 571-1032396 have a minimum order which is 500 or more for the 571-1032394 and 780 or more for the 571-1032396. Does anyone have any ideas what I could use instead?

Thanks Steve

02-27-2010, 09:27 AM
I just checked www.jameco.com and they have the transistor and the opto. Both can ship now. As you are in the UK you may want to search for other European suppliers and check if they are carrying the parts. In the states, I also use Digikey.


02-27-2010, 12:21 PM
Could I use 511-STP20NF06L instead of 511-STF20NF06?

02-27-2010, 12:23 PM
And could I use 512-2N3904NLBU instead of 512-2N3904TA?

02-28-2010, 12:21 AM
Could I use 511-STP20NF06L instead of 511-STF20NF06?
if these are for the DC SSR, they maybe. you haveto make sure the tabs don't touch. some ppl use heat shrink others just bend every other FET out of the way.

another option is to use 511-STF20N20 (they are Obsolete, but they have stock)
another option is the 511-STF40NF06

02-28-2010, 12:25 AM
And could I use 512-2N3904NLBU instead of 512-2N3904TA?
Yeap or even the 863-2N3904G will do.

just curious where is this device used?

02-28-2010, 12:29 AM
OK, that's great :), The items that are are going to cause me issues are 859-MOC3023,

Try 512-MOC3023M

02-28-2010, 11:19 AM
just curious where is this device used?

Its for the Ren-C