This is the bar I've owned for the last two years.

While serving drinks and socializing is a pretty great job

do you know what the most frustrating part about it is?

When customers leave

but forget their credit card at the bar.

It's pretty much a lose lose situation

for everyone involved.

Wired has given me one week to figure out

how to stop people from leaving the bar

without taking their credit card.

[electronic music]

We're locked on and, it's gone.

By the way, I'm Mark Kleeb,

I'm a creative technologist based in Brooklyn, New York.

I've been building custom arcade machines

for local independent game developers.

In 2019 my wife and I opened Wonderville

a Bushwick based barn arcade

that's filled to the brim with those games.

There are three main goals I have for this project;

1, figure out the best locations tracking technology

to install at the exit of the bar,

2, to be able to determine

when someone is leaving without their credit card,

and 3, figure out how to somehow get their attention

and prevent them from leaving without it.

[electronic beeping]

So, here's the plan.

Once I determine the best technology to use

I'm going to install a locations sensor by the door.

Whenever someone opens a tab

I'll trade them some kind of locations tracker

then I'll program the sensor to only go off

when someone tries to leave the bar with the tracker.

I know some of you might be thinking

well, what if someone wants to go outside

to have a cigarette?

Well, we have a backyard, they can go out there instead.

Finally, when the sensor goes off

I want to build some kind of display

that does whatever it needs to do

to stop them dead in their tracks.

The first thing I'm gonna need to do

is figure out which locations tracking technology

is best for this project.

[mellow music]

I've narrowed it down

to three different types of technology;

GPS, Bluetooth, and RFID.

Let's start by taking a look at GPS.

So, this is an Adafruit Feather Microcontroller

with a GPS add-on and what this allows me to do

is use a computer to write code to basically use this GPS

to communicate with a satellite.

If I receive a transmission back,

I can determine my latitude and longitude

anywhere on the globe.

So, I plugged in the GPS module

and I brought up some example code from Adafruit

on parsing serial data.

So, I get the time, I get the date and it's accurate, right?

However, I'm not seeing latitude and longitude

because I have fix zero.

I'm not getting a fix

and that's probably because I'm in this windowless box

where I don't have any access to a satellite

so the next step is to go outside

and see if it works outdoors.

All right, I've got a fix 40.41 North, 73.55 West,

we're locked on.

We'll see if this works when I bring it inside.

Still got a fix and, it's gone.

I think the GPS is only gonna work outside

with a clear path to the sky

as soon as we come inside, we lose the connection.

I think we can safely rule out GPS

as a tracker for this project.

Now onto Bluetooth.

This is another Adafruit board.

This has a Bluetooth module built in

so what we're gonna do is program this

to be a Bluetooth beacon,

a device that emits a Bluetooth signal.

So, I can use a Raspberry Pi computer,

with a Bluetooth module built in,

to sense if there are any Bluetooth beacons in the vicinity.

I think this can work really well

because we can install the Raspberry Pi near the door

and, if the beacon gets close, it can trigger the sensor.

I've found some example code

to transform my Bluefruit Sense into a beacon.

This is a valid beacon packet,

so this is what's gonna be transmitted.

I'm gonna get the ID, the major and minor, and the vRSSI.

This is my received signal strength indicator.

So, I'm gonna need to set up a Bluetooth receiver

and take a look at the RSSI value

to determine how far away it is from the receiver.

Theoretically, I should be able to find a threshold number

where this is right under the doorway

and trigger the display when it hits that decibel level.

I've got my beacon already plugged in and working,

I've got my Raspberry Pi here,

let's run this code and see what happens.

[mellow music]

So, I've already got a beacon working, right?

And if I zoom in here you can see the RSSI is around -45

and so it's roughly, I don't know, 12 inches away.

The next thing I want to do is plug this into a battery

and see if I can get a wider range of signal strength

just so I can determine if this is a viable solution.

All right, I'm down here in the arcade

with my mannequin friend, Manny,

he's gonna act as my customer

with a Bluetooth beacon tracker.

Got him attached to a chair with a dolly,

I've got a rope that goes all the way up to my work bench

and we're gonna monitor the signal strength

as I pull him closer.

So, I'm just gonna tape this beacon

and I'm gonna pop upstairs

and we're gonna check out the RSSI.

Okay, so we got Manny as far away as he could possibly go

and we're getting an RSSI of about -90,

far more than we could get in the booth.

So, let's pull him closer

and I'm just gonna monitor this value

and just see how it changes.

80, -80, -78, -75, -77

and we're at about -75 so, we're getting about a change,

from right up to the Raspberry Pi we were seeing -40,

all the way across the room, -90.

So, I can kind of calibrate distance now

using this signal strength value.

So, Bluetooth works.

This beacon, I can detect when it's close,

I can detect when it's far away using the signal strength.

What I don't like about it is that it needs power

so I need to make sure the batteries are fully charged

and whoever's carrying this around, if this dies,

I lose track of them so, it isn't great for that reason.

If it came down to it, Bluetooth would work,

I could make this work, but I want to see how RFID goes.

RFID, radio frequency identification.

This is pretty ubiquitous.

If you've ever used the E-Zpass,

those things that are on clothes,

if you try to walk out with them.

So, what I've got here

is a SparkFun Simultaneous RFID Tag Reader

and it's attached to an Arduino Uno microcontroller.

The RFID reader will transmit on a certain wavelength

and when a tag is within range

it will receive a small amount of energy

from that wave length and transmit back,

and if it's within the range of the RFID reader

it can trigger the sensor.

This tracker isn't powered, this is just an antenna

and how it works is the RFID reader

transmits radio waves that travel through the air

and can magnetize and power this

to send a small signal back to the reader.

That's how we can identify where this tracker is.

So, I've got some example code here

that came from the SparkFun website,

and then I'm gonna pop open my serial port

and it says, Press a key to begin scanning.

All right, so there's no RFID tags in the vicinity

and, because it's five decibels,

I probably won't see anything from more than a few inches.

Let's see if I can get these both in the shot at once.

I have my tag up here, I'm gonna slowly bring it down,

closer, closer, closer, closer, and there it is.

So, I could see my tag data

when I'm within, maybe, about two inches of the antenna.

So, unlike Bluetooth, I don't get a range,

I only see the tag or I don't.

So, we know that this works from a few inches away,

if I want to extend the distance,

I'm gonna have to install an external antenna.

And we're done.

So, I've rerouted the antenna

to go out through this external antenna, which is gigantic

but hopefully will give me the range that I need.

Let's do a range test.

I'm going to go back to my same example

that I just used before and let's take this five decibels

and you know what, let's just double it.

We'll see what we get at 10?

So, I'm gonna upload this code.

If five decibels reads from two inches away

10 decibels should theoretically work at four inches.

Let's see how far away this will work?

I'm already getting values

right about here

and this is like 18 inches.

This must be reading on a logarithmic curve,

which means that the higher the power

the distance will increase logarithmically

rather than linear.

Let's go back to Manny

and we'll see if we can get this to trigger

only when he gets close to the antenna.

Same thing we did with Bluetooth, I've got an RFID tag here,

we're gonna stick it on Manny.

I've installed the antenna on the ceiling

and we're gonna pull Manny in and hopefully,

when he's under the antenna, I can track the tag.

Okay, we're gonna start scanning

and I'm gonna reel Manny in.

Right now we're not seeing anything

but hopefully, when he passes under the antenna,

we can see the tag.

And we got a tag.

As soon as Manny passed directly under the antenna

I got a tag to show up so this is still pretty far away,

but it will work.

We'll just have to recalibrate it when it's above the exit.

Out of the three,

I think RFID is the most promising for this project.

The tags are just a piece of paper, I could afix them

to something that the person can wear or carry with them

and it seems to work from many different distances.

So, I'm gonna go with RFID now I just have to refine it.

Next up, I'm gonna start working on the display.

So, here's my plan

on how I'm going to get people's attention

when they leave the bar.

This is the door to the bar, I'm gonna install a sign,

gonna kind of look like a stop sign

that's gonna attach to the door

and it's gonna say, Close your tab.

And I'm gonna line this with LED strips

so if they try to leave, the RFID will go off,

it'll a light up this sign

and they'll see it before they leave.

I also want to have a sound component

so I'm gonna install speakers on either side of the door

and we're gonna play some sort of alarm

so that they know something is wrong if they try to leave.

Okay, so I designed this file

and my intention is to cut this out of plywood

on a CNC machine.

So, I made it in the shape of a stop sign.

Because it's being cut out of wood

I needed to use a font where everything would be attached

so that none of the letters would fall out.

I'm here with my CNC machine.

So, a CNC machine is a computer controlled cutter.

I've got a wood router attached to these motors

and I can take the file that I designed

and it will cut it out of a sheet of plywood.

So the router, I'm gonna turn it on

and it's gonna move on the X and the Y and the Z axis.

It'll look at my letters, it'll cut them out

and then it'll lift off and move to the next letter

and it'll do this in a couple passes

so it's not too heavy on the router bit.

Once the CNC machine finished, I sanded the sign down,

cut out some wood strips and glued them to the back.

My plan is to attach LED strips to the back of the sign

so the wood strips are there as a place to afix them.

It also creates some distance between the door and the sign,

so the lights can illuminate

and, finally, I added some diffusion on the front.

I don't want people to be able to read the sign

until it lights up,

so the diffusion will help to hide the letters.

So, after some testing, the LED strips

weren't really shining as brightly as I would have hoped

and you can't really read the letters so instead,

I'm gonna go with this super bright LED panel.

Yep, so this is gonna look a lot better

when it's mounted over the exit and it's a little bit darker

but here's the final display.

Now onto the speakers.

So, I wanted to play a really jarring sound

when someone tries to leave the bar

so I did a little bit of searching online

and I think I found the perfect one on.

[electronic siren beeping]

So, I put the siren sound on this MP3 player

which is plugged into this amplifier

which is then plugged into this speaker.

So, I have the siren playing on a constant loop

but you can't hear it because the amp is turned off.

This means that when someone walks under the sensor

with the RFID tag,

all I have to do is program it to turn on the power and.

[electronic siren beeping]

All right, got the display finished, got the speaker set up,

so now all I have to do is get everything working together.

[mellow music]

So, I found some code that plays a sound on a buzzer

when an RFID tag is near.

So what I did was I added an LED

because I figured if I can play a sound on a buzzer

I can also turn an LED on.

I commented these lines out

because I don't need the buzzers anymore

but I added this line of code that just turns an LED on

when it searches and finds a new tab.

So, if I start scanning

and I bring an RFID tag close to the antenna,

I can turn on the LED.

Now that I know that it works

I'm gonna replace the LED with a power relay.

So, a power relay is essentially a power strip

but it has an input for a five volt on-off switch

that I can control from the Arduino.

So, similar to how I can turn the led on and off,

I can turn on and off this power strip.

So I've plugged my display and the amp and the speaker

all into the power relay.

When the RFID tag gets close to the antenna

let's see what happens.

[electronic siren beeping]

So, I've programmed everything to turn off after 10 seconds,

so we don't have a constant siren going off,

this also will reset the code back to its original state

so we can keep scanning for more tags.

Next, I need to work on

how I'm gonna actually hand the RFID tag to a customer

when they open a tab.

So, I've got these cool snap bracelets from the '90s

and I was thinking I could attach the RFID tags to these.

So I put one on and check this out.

The sensor is no longer recognizing the tag.

Next I got these paper wristbands,

but these didn't work either.

I did a little bit of research

and I think I discovered the problem,

we're using ultra high frequencies for RFID transmission.

Inside the snap bracelet is a piece of metal,

metal interferes a lot with wireless transmission

so if you attach the RFID tag to this

it's not gonna read very well.

Similarly, on the paper bracelet,

the human body is mostly made up of water

and watery objects also cause a lot of interference.

So unfortunately,

neither of these is gonna be a great option.

So, ultimately, the solution that worked

was taking a little bit of foam

and creating some distance between the RFID tag

and the paper bracelet.

This foam is about an eighth of an inch thick,

it's adhesive, so it was really easy to attach,

and it works perfectly.

If I was gonna actually implement this in the bar

I'd probably have to come up with a more elegant solution

but since tomorrow's my last day working on this project

this will have to do.

[deep electronic music]

Okay, so the installation is pretty much done,

all that I needed to put in the exit are the speakers,

which I mounted here,

the antenna, which is right over the doorway,

and the display, which is hanging on the door.

I had to find a pathway to outside of the exit

so I could run all the speaker wires, the antenna cable,

and everything to this wall

where I've got the actual RFID reader, the power relay,

the amplifier, the ipods, and the power for everything.

So, now that we're installed

all I need to do is fine tune the range of the antenna

so that when someone walks toward the door

everything goes off at exactly the right time.

After testing it out, I think 15 decibels

is what we're gonna go with as far as the range.

The sweet spot to trigger the sensor is right about here,

just before they walk out the door.

Range is set, everything's installed, I got my wrist band,

I think it's finally time to give this a shot.

Let's go.

[dramatic music]

[electronic siren beeping]

[dramatic music]

[electronic siren beeping]

So, I think it's working pretty well.

It's going off at exactly the right time

just before they exit the door, the lights are going on,

the sound's going on and, you know,

it works exactly as I would have hoped.

So the true test is gonna be to try this out on someone

who doesn't know what's coming.

[intense music]

[plastic rattling] [electronic siren beeping]

So there we go, I think we can safely say

no one's going to leave the bar

and forget their credit card.

Overall, I'm pretty happy

with the amount I was able to accomplish in just a week.

In terms of practicality, I'm not sure this is something

I'm gonna install longterm.

The alarms are a little jarring

and I don't want it to seem like someone's shoplifting

but I think it's a cool experiment and I think the customers

are gonna have some fun with it.

I had a great time building this project,

it was really fun to work with the different technologies.

Maybe everything didn't go exactly as planned

but that's part of the process and part of the fun.

[synthesized dinging]