Instructables

Use a DIY Pressure Plate Switch to Automate Your Haunted House

Featured
Picture of Use a DIY Pressure Plate Switch to Automate Your Haunted House
IMG_6503.JPG
IMG_6442.JPG

When running a large haunted house, you want most of the special effects to be automated. But for this to be effective, you need to get the timing right. The best way to do this is to use sensors to detect where your guests are.

In this project, I am going to show you how to make a simple DIY pressure plate switch. This is just a pressure sensitive switch that is activated when someone steps on it. A sensor like this is really useful for effects that require someone to be in a specific location.  I also give several examples of ways that you can use it to activate special effects in a haunted house. 
 
Remove these adsRemove these ads by Signing Up

Step 1: Materials

Picture of Materials
IMG_6625.JPG
IMG_6626.JPG
Here are the materials and tools that you will need to make your DIY pressure plate switch:

Materials:
3 Large Sheets of Cardboard
Aluminum Foil
Tape
Several Feet of Insulated Wire 

Tools:
Wire Strippers
A Sharp Knife

Step 2: Attach Foil to Two of the Cardboard Sheets

Picture of Attach Foil to Two of the Cardboard Sheets
vlcsnap-2013-10-06-10h55m52s81.png
vlcsnap-2013-10-06-10h57m06s52.png
Img_6434.jpg
Tear off a piece of aluminum foil that is at least as big as the cardboard sheets. Lay it centered on the cardboard. If the foil hangs over the edge of the cardboard wrap it around to the back side. Tape one side of the foil to the cardboard. Then stretch the foil tightly and tape the opposite side. Do this for all four sides of the foil. 

Repeat this process with a second sheet of cardboard and foil.

Step 3: Attach Wires to the Foil with Tape

Picture of Attach Wires to the Foil with Tape
vlcsnap-2013-10-06-10h34m19s225.png
vlcsnap-2013-10-06-10h34m31s85.png
vlcsnap-2013-10-06-10h35m06s180.png
vlcsnap-2013-10-06-10h35m17s33.png
Take one wire and strip about one inch of insulation off of the end. Then lay it on the first sheet of cardboard so the the bare end of the wire is touching the aluminum. Apply a piece tape on top of the wire to hold it in contact with the foil. Repeat this with the second wire and the second sheet of cardboard. This isn't the most secure way of attaching the wires but it should hold together for Halloween. 

Step 4: Cut Out the Center of the Third Sheet of Cardboard

Picture of Cut Out the Center of the Third Sheet of Cardboard
vlcsnap-2013-10-06-10h29m27s100.png
The third sheet of cardboard is used as a spacer between the other two sheets. To make this work, we need to cut out the center of the third sheet of cardboard.

Trace a rectangle on the face of the cardboard that is offset from the edge by about one inch. Then using a sharp knife, cut out this rectangle.

Step 5: Assemble the Pressure Plate Switch

Picture of Assemble the Pressure Plate Switch
vlcsnap-2013-10-06-10h29m37s214.png
vlcsnap-2013-10-06-10h29m43s27.png
vlcsnap-2013-10-06-10h29m54s139.png
vlcsnap-2013-10-06-10h30m01s193.png
Now it is time to assemble the pressure plate switch. Lay down the first piece of cardboard with foil side facing up. Then set the cutout piece of cardboard on top of it. Place the third sheet of cardboard on top of the cutout with the foil side facing down. Lastly, attach the three layers together with tape.

This is the completed pressure plate switch. When you press on the center of the cardboard, the two foil sheets will make contact and complete a circuit just like a regular switch. Now all you have to do is find some way of disguising the pressure plate so that it is not noticeable. The easiest way to do this is to put it under a light rug. 

Step 6: Use the Pressure Plate Switch to Activate an Arduino Program

Picture of Use the Pressure Plate Switch to Activate an Arduino Program
IMG_6507.JPG
Img_6517b.jpg
Img_6600b.jpg
4.jpg
One way that you can use a switch like this is to activate an Arduino program. This works just like any other external switch that you might use with an Arduino. Connect one wire to the GND pin. Then take the other wire and connect it to an input pin and also connect it to the 5V pin with a 1k resistor.

The resistor acts as a pull-up resistor. It will make the input pin read HIGH when the button is not being pressed. But when the button is pressed the switch connects the input pin to GND and the input will then read LOW. You can then use this signal to activate any kind of sequence that you like.



//Here is an example of code that you could use with this switch.
const int buttonPin = 2;     // the number of the pushbutton pin
const int ledPin =  13;      // the number of the LED pin

// variables will change:
int buttonState = 0;         // variable for reading the pushbutton status

void setup() {
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);     
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);    
}

void loop(){
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pressed.
  // if it is, the buttonState is LOW:
  if (buttonState == LOW) {    
    // turn LED on:   
    digitalWrite(ledPin, HIGH); 
  }
  else {
    // turn LED off:
    digitalWrite(ledPin, LOW);
  }
}

Step 7: Use the Pressure Plate Switch as an Auxiliary Switch for DC Electronics

Picture of Use the Pressure Plate Switch as an Auxiliary Switch for DC Electronics
Image3b.jpg
F1SD7BFGVVP87M1.LARGE.jpg
vlcsnap-2013-10-06-10h31m32s84.png
vlcsnap-2013-10-06-10h31m28s45.png
You can also use the pressure plate switch to activate function on small DC electronics. By wiring the pressure plate switch in parallel with an existing momentary switch, you can use it to activate that function just like the original button. As an example, I am going to be using a small sound module to play sound effects when the pressure plate is stepped on.

Start by removing the housing of your electronic device. Then locate the button for the function that you want to activate. In this case it is the play button. Find a good place on both sides of the button to connect the wires from your pressure plate. In most cases one side of the button will be wired to the microchip and the other side will be connected to either ground or the positive supply voltage. On my circuit there was an open pin hole on one side of the button so I connected one wire there. The other side of the button was connected to ground so I connected the second wire to the negative terminal of the battery. 

After making these connections, any time that the pressure plate is stepped on, the sound module will play your sound effects.

Step 8: Use the Pressure Plate Switch with a Relay to Activate AC Electronics

This kind of pressures plate switch can only safely switch small DC voltages. So if you want to use it to activate AC appliances, then you need to add a relay to isolate the switch from the AC power line. To set this up, you will need the following materials:

Materials:
Relay (with a 12 volt coil and contacts rated high enough for your AC appliance)
Insulated Connectors (that match the terminals of your relay)
Insulated Plastic Housing
Extension Cord
12 volt power supply or battery 

Tools:
Wire Strippers
Sharp Knife

Start by cutting the extension cord into two pieces. If necessary also cut the wires coming from the power supply and the pressure plate. Then strip about 1/2 inch of insulation off the cut ends of all of the wires. Then attach insulated connector to the ends. Use one male connector for one of the wires from the power supply. The rest of the connectors should be female.

Connect one wire from the pressure plate to the power supply. Then connect the other wires from the pressure plate and power supply to the coil terminals of the relay. Connect the male end of the extension cord to the common terminals of the relay. Then connect the female end of the extension cord to either the normally open or the normally closed terminals depending on whether you want the appliance to turn on or off when the pressure plate is stepped on.

The last step is to put the relay in an insulated plastic housing. Use your knife to cut slots in the sides for all the power cords. Carefully fit the relay and power cords into the housing and close it up. 

As an example, I connected the female end of the extension cord to the normally closed terminals of the relay. Then I plugged a lamp into the plug. The lamp is normally on, but when someone walks into the room and steps on the pressure plate, the lights will suddenly turn off. 

Step 9: Alternate Designs

Picture of Alternate Designs
vlcsnap-2013-10-06-10h30m29s229.png
This pressure plate design works well in most circumstances. However, you can make a sturdier version of this design by using thin sheets of wood instead of cardboard. You can also replace the aluminum foil with thin sheet metal. Select the materials that are the most appropriate for your application.
kaylah33425 days ago

Can you please explain exactly how to connect the wires to the battery pack and light bulb? thanks

Take a 12V battery or power adapter. Connect one wire to the coil of a relay and the other wire to the pressure plate. Then connect the other wire on the pressure plate to the other terminal to the coil on the relay. Now when the pressure plate is stepped on, the relay will activate. You should hear a clicking sound.

Then take an extension cord and cut it in half. Separate the wires for a few inches and strip the insulation off the ends. Connect the two wires from the male end of the power cord to the common terminals on the relay. Then connect the two wires from the female end to either the normally closed or normally open terminals on the relay depending on whether you want the light to turn on or off. Then just plug your light into the female end of the power cord.

I put one of these together last year. Normally, a string of jack-o-lanterns is on, but when you step on the switch the jack-o-laterns turn off and a ghost turns on. spooky, right? is there a way to extend the amount of time the ghost is illuminated after the switch is released?

There are time delay relays. Or you could make a time delay relay circuit with a capacitor and a could of transistors. You can search for examples online. Or you could use a relay latching circuit.

ok, I think I got it, thanks!

I like it . It's so simple but also extremely awesome

Just from watching the youtube video my mind is flooded with all kinds of projects I wanna experiment with now! lol Its beautifully simplistic which makes me want to try it immediately!

nbfox11 months ago
I most definitely was shorting 5V to ground. Sometimes I have to do stupid things and ask stupid questions to get things done the right way. Thanks for your help. Should be a cool little project.
nbfox11 months ago
So I have wired the switch up to the microcontroller. I wired 5V from the microcontroller to one end of the switch, and ground to the other, along with the pull up resistor. However, every time I close the switch my Arduino actually powers off.... Anyone else have this problem? Any help would be greatly appreciated.
DIY Hacks and How Tos (author)  nbfox11 months ago
Check how you have it wired up. If you are shorting the 5V to ground, you would overload the board.
Kzummo11 months ago
Who said it had to be for halloween only?
foobear11 months ago
Seems like with extended use the cardboard would start to sag together in the middle and be constantly touching together... How long before this happens?
DIY Hacks and How Tos (author)  foobear11 months ago
It all depends on how hard you are on it. It could probably hold up to a night a 10-year-olds occasionally stepping on it. But if you want to use it for a longer time with larger adults, then you probably want to use the wood paneling and sheet metal that I mentioned in the last step.
DaBlakus11 months ago
You can omit the pullup resistor and use the internal pullup resistor by setting the input pin "HIGH". Just use the digitalWrite "digitalWrite(buttonPin,HIGH)" instruction and set the input pin high in the setup list.
djkraz11 months ago
Very nice instructable! I have created several similar for our haunted house however I use aluminum duct tape in strips on cardboard like yours but then use thin double sided foam insulation (for insulating windows & doors etc.) to separate the 2. It works great and you can make it much bigger without having to worry about the middle becoming bowed and giving a constant short. Picture a tic tac toe board with a border as the strips of foam insulation.
carlos66ba11 months ago
Nice instructable. If you use arduinos, another option is to use ultrasonic sensors to detect people. They can be had on ebay for as little as $1 a piece! (amazing, isn't it?)
bremus carlos66ba11 months ago
But then you need an Arduino which is more than $1.
naw going old school is way better. plus when yr done u can recycle the aluminum 4 money as well.
Awesome this will help so much!