View Full Version : Powering the Grinch?

11-02-2007, 11:31 PM
I have successfully built and tested the Grinch board powering it with a separate 5vDC and ground into the J2 pins.

I am now trying to clean things up a bit and would like to power the board through pin 1 on the RJ45 as mentioned in the Construction Notes. If I chose this option where does the ground come from?

Wayne J
11-02-2007, 11:35 PM
Put your power supply's ground on pin 3 of the RJ45, this is the same pin that LPT pins 18-25 are on, which are grounds.

11-03-2007, 12:03 AM
I guess I'm still a little confused. Right now I have the DB-25 pin 18 (which I understand is a ground) connected to the RJ-45 pin 3. Is this sufficient ground for the 5vDC source or do I also need to connect the 5vDC ground to the RJ-45 pin 3?

I am using one of the DB-25 to RJ-45 adapters.

Wayne J
11-03-2007, 12:17 AM
Yes, you want the DB-25 pin 18 and the power supply ground on pin 3 of the RJ45.
It a good idea to use more than one of the ground pins ( 18 - 25) of the LPT.

11-03-2007, 09:11 AM

12-21-2007, 10:18 PM
I am ready to fire up my Grinch for the first time. I have been unable to find a reasonably priced variable DC power supply.

I found a wall adapter from a DSL router that I've had at my office for a long time that has been collecting dust and ready to be tossed. The DC output is 5Vdc, 3.0A.

Will this work for the Grinch?

I am not sure exactly how much power is needed to trigger all 64 triacs, but it seems that the power needed to trigger the Triacs is in the 50 mA range. 64 x 50 mA = 320 mA. Am I on the right track?

12-21-2007, 10:26 PM
I wouldn't use the wall wart unless I knew it was filtered and regulated. Don't exactly know what that means, but it is the first response out of everyone who seems to know anything about this stuff.

You already have a 5 volt power supply, its in your PC. or are you running from a laptop?

Most just grab power from their PC and run it straight into the Grinch. If not that, then a spare APS from some computer that is/was getting throuwn away. How are you trying to drive your Grinch - laptop or desk top?


P. Short
12-21-2007, 10:31 PM
Go with what Steve says. At the very least make sure that it is regulated, since I'm not sure how it could be regulated without being filtered as well.



12-21-2007, 11:41 PM
My plan was to use a laptop as I have have an older one that hasn't seen much use in a while, so no power supply to draw from it.

I've thought about the APS senario and I was was planning to go up to the dump where they have an electronics recycling progam and see what I can find. I also found some one on Craigslist who's giving a P3 computer for free, it just needs a hard drive. I'm not too confident that it will run, but if it does work after I throw a hard drive into it, I'll just run Vixen from it, otherwise it will be cannibalized for the APS. I'm thinking this might be the cheapest option.

Does anyone have a lead on a variable power supply that is less than $90?

Is there any way to regulate or filter a wall wart?

Wayne J
12-22-2007, 12:23 AM
scroll down to 'Power Supplies'


12-22-2007, 01:02 AM
You can still uce a PC power supply, but it does not have to be in a PC to use it! Go visit your local PC store and see if they have an old used AT power supply (these had the old push & click buttons that turned the mains on) - many shops will give you one or only charge you a few $ at most for it.

If you manage to get an ATX - the sort that have a momentary pushbutton like most modern PC's no worries, just connect the green wire in the 24 connection loom to ground (black) and the supply will stay on

I usually open the supply and rip out all but one or two power outputs as I dont really need all the additional cables & they make things messy. Then you have a cheap 5V (red to black) or 12V (Yellow to black) supply for your systems.

12-22-2007, 01:26 AM
My plan was to use a laptop as I have have an older one that hasn't seen much use in a while, so no power supply to draw from it.

Is there USB on the laptop by chance? I'm sourcing my 5v from this port.

12-22-2007, 01:59 AM
USB is good for about 200 to 500mA so it might be a good option, yeah

P. Short
12-22-2007, 02:12 AM
If I recall right, it may current limit at 100 mA until the attached devices are recognized and configured by host firmware. Not the best choice for powering the Grinch.

The PS2 port isn't subject to these limitations, I think that it is normally good for 500 mA.



12-23-2007, 11:47 PM
I went to the dump yesterday to look for power supplies at the recycling center. The guy there said look and take whatever you want. I was perusing what they had when a lady was dropping off a P3 mini tower with a Windows XP sticker on it. So I gladly helped her with it right to my truck. After a few hours of of cleaning up the software, messing with the bios to fix the CD drive; and setting up the power for the Grinch, I have it the PC fired up, and the Grinch is fired up too. :mrgreen:

Now if I just had those terminal blocks from Mouser to finish the SSR's.....hmmm, I guess I'll have to wait.

Wayne J
12-24-2007, 12:01 AM
WOW, what a score JEEPGUY. Cool deal! :)

12-24-2007, 05:00 AM
Nice score Jeepguy :)

12-24-2007, 10:14 AM
Nice score