Ztrains: The Grassinator, Static Grass Applicator

Why Static Grass?
In this article we'll show you how to build your own electric static grass applicator, or as we like to call it around the Ztrains office... The Grassinator. For right around $35.00 and a trip to your local hardware store and nearest Radio Shack, you'll be ready to build your own Grassinator in an evening.

To see a similar device in action you can watch this video by Joe Fugate at the Ztrains Theater: Our design is based on a 12 VDC negative ion generator. Negative ion generators provide an electrical charge to individual static grass fibers and the Grassinator design takes advantage of this charge by supplying a convenient path to ground... in this case your layout. The result is static grass that stands upright.

Parts List
We've listed specific parts and part numbers as well as vendors, when possible, to make buying the Grassinator components a bit easier for you. Bear in mind these are the parts we've used on our Grassinator and not your only options. The only specific piece you'll need is the negative ion generator. If you're feeling creative you can substitute parts as you see fit. We suggest reading through this text and viewing all photos and illustrations first. This parts list is accurate as of May 2008.

Part Name	Where To Buy	Part #	Price
12 VDC negative ion generator	Electronic Goldmine	G9695	$13.95
12 VDC 100mA power supply	Electronic Goldmine	G15216	$0.99
3/32" submini phone jacks	Radio Shack	274-245	$2.99
SPST rocker switch	Radio Shack	275-694	$2.99
Mini alligator clips	Radio Shack	270-380	$2.79
Dremel 1/2" drum sander	Home Depot	407	$5.00
Package of small spade lugs	Home Depot		< $1.00
1-1/2" PVC drainpipe, 12" long	Plumbing / Hardware		< $3.00
1-1/2" PVC test cap (2)	Plumbing / Hardware		< $2.00
Rubbermaid, 4 oz. container	Supermarket		< $3.00
Metal window screen	Hardware		< $3.00

In addition to the parts listed above, a few basic items such as a saw, electric drill with assorted bits, hookup wire (we recommend 22 gauge stranded), soldering gear, wire nuts and epoxy would be useful.

Step-By-Step


	PVC pipe and test caps


	PVC test caps


	Dremel sander


	Grass bowl cleaned up

Step 1: Cut the 1-1/2" PVC drainpipe down to 6" in length. These drainpipes have a small flange, or lip, at one end. You'll want to cut this part off.

Step 2: You'll need to drill two holes in this 6" length of pipe. Use a 5/32" drill bit for this first hole, this will be for the panel mount jack. Make this hole 1-1/4" from the top of one end of the pipe. For the second hole use a 1/16" drill bit and make this hole 2" from the top of the same end of the pipe. This will give you two holes on the same end of the pipe with 3/4" of space between the holes.

Note: There is usually a visible mold line on these PVC pipes, use this line as a guide so your two holes will line up vertically.

Step 3: A single hole must be drilled into each PVC test cap. Let's drill the hole for the on/off switch first. In the center of one PVC test cap, drill a 3/4" hole. In the other test cap drill a 1/8" hole. You can make the hole in this second test cap off center a bit, though hole placement is not critical here.

Step 4: Two holes, each approximately 1-1/2" must be made in your Rubbermaid container, one in the center of the lid, and one at the bottom of the bowl. I say approximately 1-1/2" because the exact size will be determined by the size of the PVC test caps you buy (these can vary a bit in size from manufacturer to manufacturer). I use the Dremel 1/2" drum sander to make these holes, sanding the hole a little bit at a time to insure a snug fit with the PVC test caps.

Step 5: Now we get to use the Dremel 1/2" drum sander again to modify the housing of the negative ion generator. The generator has a molded tab on one side for mounting. We need to remove this tab in order to fit the generator inside the PVC drainpipe. You want to get the tab side flush with the top of the generator. Also you'll need to gently sand the other corners of the generator to remove some of the plastic housing.

Note: Be very careful when sanding down the edges of the generator... we only want to remove enough of the housing to allow the generator to fit snugly into the PVC drainpipe. We don't want to sand so much that we breach the generator housing. Remember... go slow!


Negative ion generator		Sand the mounting tab		Test fit your work

Ok, the hard work is over and we're very nearly done. Before we begin wiring the up the Grassinator, do a "dry fit" of all your components to insure everything fits as it should.

Step 6: Insert a long length of your hookup wire into the small hole in the PVC drainpipe. Make this length of wire approximately 2' long, we can cut it down later if you'd like. Fish, or push / pull, this wire through the small hole and up through the top of the handle. The wire should be a snug fit, which is why we're pushing this wire from the outside into the handle. It's important to get this wire in place right now before we begin attaching the other components.

Step 7: Insert the SPST rocker switch into the PVC test cap with the 3/4" hole and tighten it down with the included lock washer.


Grassinator pictogram		Simplified wiring diagram		Actual wiring harness

This next step is really the only "tricky" bit of wiring you'll encounter. The submini phone jack has three solder tabs, one in the front of the jack and two in the back. The tab is the front is our ground (-) tab, the tab diagonally opposite the front tab is our positive (+) tab. The tab in between these is not used. We need to make a total of 4 solder joints now. I use red wire for positive (+) and black wire for ground (-) just to keep things visually clear for myself.


	SPST switch / submini jack

Step 8: Solder a 4" piece of (black) wire to the ground (-) tab on the jack. Let the other end of this wire alone for a moment.

Step 9: Solder a 3" piece of (red) wire between the positive (+) tab on the jack to one side of the SPST rocker switch, either side is fine.

Step 10: Solder a 4" piece of (red) wire to the unused side of the SPST rocker switch. Let the other end of this wire alone for a moment.

Step 11: Now we tie up the two loose wires from our soldering job. The ion generator has three wires attached to it. A red and black wire on one side, a thicker red wire with a PC board / needle assembly on the other side. Leave the needle assembly wire alone for a moment. Attach the loose end of the positive (+) wire from the rocker switch to the red wire on the generator. I use small wire nuts for this

Step 12: Attach the loose end of the ground (-) wire from the jack, along with that first wire we inserted through the pipe, to the black wire on the generator, again use a small wire nut to bundle all three wires together.

Step 13: Ok, time to assemble. You can now cut off the PC board / needle assembly. Gently push the generator onto the pipe with the thick red wire going in first. Push it down to about 1" from the far end of the pipe.

Step 14: Next, unscrew the round nut / collar from the jack and insert the jack in to the pipe and push it through the hole we drilled earlier. Once through, screw the round nut / collar back on to the jack to secure it.

Step 15: Fit the PVC test cap with the rocker switch onto the pipe.

Step 16: Push the red wire through the hole in your PVC test cap / Rubbermaid bowl assembly. You'll want to work this wire through until the pipe and the test cap mate up. Fit the pipe and cap together.


Lid with metal screening		Spade lug in grass bowl		Completed Grassinator

Step 17: Cut a round piece of aluminum screen material for the Rubbermaid cap. Depending on which Rubbermaid bowl you buy... many of the lids have an inner "lip". If you cut your screen material just a little large it will "press-fit" inside this lip and hold firmly.

Step 18: Add a small spade lug to the end of the wire coming out of the Rubbermaid bowl. You can coil your wire just a bit in the bowl in order to make the wire act like a spring. When you place the top of the container back on the bowl the lug will make sufficient contact with the screen material to give you a good electrical path.

You Now Have A Ztrains Grassinator!
Congratulations... you're now ready to create grassy fields. Operating the Grassinator is simple. Fill the Rubbermaid bowl with static grass, brush on a high strength adhesive to your base then place a nail into the ground through the adhesive. Attach the alligator clip to the nail, turn on the Grassinator then gently shake the grass from the bowl. Allow the adhesive to dry, and you have upright static grass!

	IMPORTANT NOTES:
	This static grass device is based on a 12 VDC negative ion generator and produces 15kV of electricity, the utmost in care is required when dealing with any high voltage device.
	Electronic Goldmine also suggests using this negative ion generator with a 9 VDC battery as well as with a 12 VDC wall wart. We do not recommend this.
	We've chosen this specific 12 VDC power supply from Electronic Goldmine for two reasons. First, it is the recommended voltage for this ion generator. Second, it costs just $0.99!
	Since this 12 VDC power supply uses the sleeve portion of the plug as ground, you may receive a slight static shock if you touch the submini nut / collar when the unit is turned on.

Electronic Goldmine: www.goldmine-elec.com
Radio Shack: www.radioshack.com
Thanks to Richard Cooke and Joe Fugate.

July 7, 2008

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