Making a Transparent Discharge Plate
Constructing A Transparent Electrode
As stated previously, the transparent discharge plate is constructed from three main components; a 4" x 5" piece of glass with a transparent conductive tin oxide coating on one side, a rectangle ring electrode made from thin adhesive copper foil, that is 1/4 inch wide and 2 mils thick, and two .005 thick pieces of transparent plastic, as shown in Figure 2 below.
|Figure 3 - Conductive Glass||
Figure 4 - Determine the tin oxide
coating side of the glass
So, to determine the tin oxide coating side of the glass you need an ohmmeter. Inexpensive VOM's (volt-ohm-meters) are available from local electrical store. Set the VOM to read OHMS on lowest resistance setting. Bring both probes in contact with one side of the transparent electrode material. The side with the conductive coating will deflect the meter, see figure below. The meter shown above(Figure 4) is on its lowest resistance setting and is showing a resistance of 165 ohms per inch.
The electrode is made from thin adhesive copper foil. You can easily cut this material with a scissors.
Begin by cleaning the tin oxide glass, thoroughly so you have a good surface for the copper foil to adhere to. Re-clean the surface throughout the assembly process to ensure that no prints or lint are left on the glass.
|Figure 5||Figure 6|
Test assembly with an ohmmeter before proceeding. Touch the tab of the ring electrode with one probe and touch the tin oxide coating with the other. You should show good conductivity (low resistance).
Next, solder approximately 18 inches of high voltage wire to the protruding tab. the wire should lay perpendicular to the copper tab as shown in Figure 7. Try to solder the wire so that it lays as close to the glass as possible. This will connect the transparent discharge plate to the HV source when you are finished.
Since the conductive coating of the transparent electrode is delicate we need to protect it. Purchase two sheets of transparent plastic which is approximately .005 thick. Cut the plastic sheet to size adding 3/4 inch to all sides of the transparent electrode.
Run a thin bead of clear silicone adhesive around the edge of the transparent electrode, on top of copper foil, as shown in Figure 8. Center the plastic on top of the conductive tin oxide coating (Figure 9). Place a book or flat object onto the transparent electrode to hold the assembly tight and together while the silicone cures. Curing time is approximately 12 - 24 hours.
|Figure 8 - Running Bead of Silicone||Figure 9 - Center Acetate over Electrode|
Once the silicone is dry, repeat this process on the opposite side of glass by running a bead of silicone around the edge of glass and centering second piece of plastic on top of glass, as demonstrated in Figures 10 and 11. Place a book or flat object onto the transparent electrode to hold the assembly tight and together while the silicone cures. Wait another 12 -24 hours.
|Figure 10 - Running Bead of Silicone on Glass side||Figure 11 - Center Second Sheet of Acetate|
You should now have the transparent electrode sandwiched between two sheets of transparent plastic. Next, fill the gap from the edge of the glass to the outside edge of the plastic sheets with silicone adhesive, see figure 12. Place a book or flat object onto the transparent electrode once again to hold the assembly tight and together while the silicone cures. Allow to dry completely before continuing.
|Figure 12 - Fill Gap Between Acetate Sheets with Silicone||Figure 13 - Electrode Sealed in Silicone and Acetate|
Create a frame for your transparent electrode by running black electrical tape along the edges of the transparent electrode to further secure the plastic sheets together (see Figure 14).
|Figure 14 - Framing Electrode|
First, run the tape along the edges of the transparent electrode. When you reach the edge that has the HV wire protruding from the side, use an Exacto knife to cut a slice in the tape, so that the tape can be secured to electrode without leaving a gap. Figures 14 -18 demonstrate this process.
|Figure 15 - Taping Edges of Electrode||Figure 16 - Cut Slit for Wire|
|Figure 17 - Fold up Small Piece of Tape||Figure 18 - Finish Taping Along Edge|
Then, wrap it around the glass on each side to cover the space between the edge of the electrode and where the copper foil appears, as demonstrated in Figures 19 and 20.
|Figures 19 & 20 - Wrap Tape Around Glass to Cover from Edge to Copper|
The tape serves a dual purpose. First, it helps secure the plastic sheets to the transparent electrode. Secondly, it provides insulation along the edge of the electrode where it is needed. You may want to double tape the corner edges to provide an additional measure of insulation.