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View Full Version : Pressure plates and relays Oh My! A quick look, without pictures, but with diagrams



Gebbinn
10-14-2011, 08:33 PM
Ok, My camera is DOA, so no pictures today.

Below are diagrams for my setup for some of the halloween display elements. I bought 10 latching relays, but they were not flip flop capable, so I had to use 2 of them on each element to get the flip flop i needed for the latching element to work. Then, because they are not rated for 110v 10a, I needed to use relays that would handle that. I had those on hand, so rather than buying more relays, I just did a lot of wiring.

it all works, and that is what matters.



The pressure plates(PP) are made by using 18g stranded wire, aluminum foil and cardboard. (I found this on the net months ago, didnt save where I found the idea, I just remember because it is so simple, this is NOT my original idea) Measure and cut off aluminum foil to the same size as your cardboard. (I used wide aluminum foil, so I could make a large PP without using 2 pieces of foil.) Strip about 2" off the end of a piece of wire, spread it out, and tape it to the dull side of the aluminum foil. Now, glue the foil, dull side down, to the cardboard. I then put duct tape around the entire thing, overlapping the edges of the aluminum by about 1". Make 2 of those, same size. Now, get some very thin foam, or lining material. Cut out a sheet a little larger than your cardboard. Cut holes in the middle of the material, and all around the outside. I have more than 50% of my aluminum foil showing. Tape the lining in place, making sure to leave a healthy amount of foil exposed. Now, put the 2 sheets together, aluminum foil together, and tape them together. Get your multimeter out, and verify that you do not have a complete circuit, and that when you put pressure on the PP, you do have a complete circuit.


The first diagram is for a dual channel opposite on/off system. When one is on, the other is off.
The second diagram is for a single channel, but needed 2 110v relays because I have more than 10a of power consumption at startup, so I used 2 relays to make it work. It turns all channels on at once, or off at once.


1178511784

Jrd
10-14-2011, 09:08 PM
Your diagrams are kinda small and hard to read, can you make them bigger?

dirknerkle
10-15-2011, 09:38 AM
Your diagrams are kinda small and hard to read, can you make them bigger?

ROFLMAO!!!

More like i-n-v-i-s-i-b-l-e !!!

Mactayl
10-15-2011, 09:44 AM
He is using white lines to draw with, can't you tell...:p

Gebbinn
10-15-2011, 12:51 PM
Ok, I fixed the pictures in the original post so you can see them. For some reason the forums were resizing the pictures on me. I think it was because paint was set up to draw a 2'x2' picture.

Jrd
10-17-2011, 03:53 AM
Ok, I fixed the pictures in the original post so you can see them. For some reason the forums were resizing the pictures on me. I think it was because paint was set up to draw a 2'x2' picture.

Ahh, that's much better.

Gebbinn
10-17-2011, 06:26 AM
Does anyone see any problems with this setup? I have done extensive testing to ensure everything works properly, but I am not an electrician. Is there any chance anyone could get hurt stepping on one of these pressure plates? I know relays are supposed to keep electrical current separate, and I only have 5v to the pressure plates, and am only putting the ground side to the pressure plates, but I am still worried.

Mactayl
10-17-2011, 06:50 AM
put carpet or a small rug over them if your worried about it, they should still work,,, are the inside or outside?

DaveJZ
10-17-2011, 08:28 AM
The only real issue I see it is using cardboard, the cardboard will eventual wear out like an old box and the connection would fail.
I would think you could use a piece of 1/4" luan plywood instead of cardboard. That should make them more durable and the plywood should still give enough to make the connection and it shouldn't wear out like the cardboard will.

Gebbinn
10-17-2011, 11:11 AM
They will be inside, and they will have non-stick rubber matting over the top of them. The haunted house will only run for 6 hours, one night, so wearing out shouldnt be a problem.

n1ist
10-17-2011, 02:42 PM
Your diagrams are hard to read, but appear to have one side of the 110v line tied to one side of the DC supplies, and to the pressure plates. Please DO not do that as it is a major safety hazard. Since you are already using relays, it's easy to keep the DC side of the world totally isolated from the AC side.
/mike

Gebbinn
10-17-2011, 03:27 PM
Your diagrams are hard to read, but appear to have one side of the 110v line tied to one side of the DC supplies, and to the pressure plates. Please DO not do that as it is a major safety hazard. Since you are already using relays, it's easy to keep the DC side of the world totally isolated from the AC side.
/mike

In the diagram, all of the grounds are tied together yes. I did not think it would matter much for the diagram, but in reality, all the grounds are separated. It made the diagram much simpler to keep the grounds in one place, rather than have even more of the wires crossing each other. In reality, the pressure plates and the latching relays are tied to 5vdc ground, the regular relays are tied to 12vdc and the plugs are tied to 110vac.

Jrd
10-17-2011, 03:30 PM
Your diagrams are hard to read, but appear to have one side of the 110v line tied to one side of the DC supplies, and to the pressure plates. Please DO not do that as it is a major safety hazard. Since you are already using relays, it's easy to keep the DC side of the world totally isolated from the AC side.
/mike

Ah yes, the neutral of the lights is tied to the DC ground.

Gebbinn
10-17-2011, 07:17 PM
Ah yes, the neutral of the lights is tied to the DC ground.

again, I refer to the post before yours. I did not in fact tie the grounds together, they are all separate, I only tied them together in the diagram for simplicity sake.

Jrd
10-17-2011, 09:03 PM
again, I refer to the post before yours. I did not in fact tie the grounds together, they are all separate, I only tied them together in the diagram for simplicity sake.

I am sorry, I did not see your reply before posting.

Gebbinn
10-17-2011, 11:15 PM
again, I refer to the post before yours. I did not in fact tie the grounds together, they are all separate, I only tied them together in the diagram for simplicity sake.

Sorry, that came across a bit short. I was in a hurry when posting, the missus was rushing me out the door.